NONDESTRUCTIVE
TESTING HANDBOOI{
Second Edition
T
5
r
VOLUME 10
NONDESTRUCTIVE TESTING OVERVIEW
Stanley Ness
Charles N. Sherlock
Technical Editors
Patrick O. Moore
Paul McIntire
Editors
\
\
"
137
l
AMERICAN SOCIETY FOR
NONDESTRUCTIVE TESTING
-
Gopyright © 1996
AMERICAN SOCIETY FOR NONDESTRUCTrVE TESTING, INC.
AU rights reserved.
No part of this book may be reproduced, stored in a retrieval system or transmitted, in
any form Or by any means - electronic, mechanical, photocopying, recording or
otherwise - without the prior written permission of the publisher.
Nothing contained in this book is to be construed as a grant of any right of manufacture,
sale or use in connection with any method, process, apparatus, product or composition,
whether or not covered by letters patent or registered trademark, nor as a defense against
liability for the infringement of letters patent or registered trademark.
1\
The American Society for Nondestructive Testing, its employees and the contributors to
this volume are not responsible for the authenticity or accuracy of information herein, and
opinions and statements published herein do not necessarily reflect the opinion of the
American Society for Nondestructive Testing or carry its endorsement or
recommendation.
The American Society for Nondestructive Testing, its employees, and the contributors to
this volume assume no responsibility for the safety of persons using the information in this
book.
'11
1\
Library of Congress Cataloging-in-Publication Data
Nondestructive testing overview I Stanley Ness, Charles N, Sherlock, technical editors.
Patrick 0, Moore, Paul M. Mcintire, editors.
p,
em. - (Nondestructive testing handbook; v, 10)
Includes bibliographie references and index.
ISBN 1-57117-018-9
1. Non-destructive testing. 2. Non-destructive testing-Industrial applications,
3. Engineerinb1rl.sp~n, 1. Ness, Stanley. II. Sherlock, Charles N. III. Moore,
Patrick 0, IV: Mcintire, Paul, v: American SOcietyfor Nondestructive Testing,
VI. Series: Nondestructive testing handbook (2nd ed.) ; v 10
96-25138
TA418.2.N65 1996
CIP
620.1'1~7-dc20
Pltblished by the American Society fOr Nondestructive Testing
1
PRINTED IN THE UNITED STATES OF AMERICA
Ii
PREFACE
The second edition of the Nondestructive Testing Handbook comprises ten volumes, 17,000,000 characters, 6,573
pages and more than 5,000 illustrations. Three Handbook
Development Directors (John Summers, Albert Birks and
Roderic Stanley) managed progress of the edition through
the Society's very .active Handbook Development Committee. Fifteen technical editors undertook the task ofvalidating
the technical content of documents covering dozens of
sophisticated nondestructive testing methods.' Key manuscripts were. submitted by 104 lead authors, supported by
more than 750 contributing authors. Peer reviewers numbered nearly 600. For the fIfteen years between 1981 and
1996, three editors-in-chief labored to establish technical
protocols and to give the series a consistency of style and
voice. Those editors were Robert C. McMaster (Volumes 1
and 2), Paul McIntire (Volumes3 through 10) and Patrick O.
Moore (Volumes 8, 9 and 10). Their work relied completely
on the efforts of those many volunteers and resulted in a significant contribution to the technical literature, at an important time for the American nondestructive testing industry.
The technical accomplishments of the Nondestructive
Testing Handbook stand as a tribute to the volunteer spirit.
ASNT could not have built the second edition without the
unwavering commitment of its volunteer contributors.
Experts in every field of nondestructive testing voluntarily
developed outlines to cover the science and use of their
nondestructive testing techniques, developed strategies for
\vriting the chapters, reviewed, corrected and re-reviewed
everyone of those 17,000,000 characters. Volunteers have
ofte~ expressed their reasons for doing this work: the overwhelming majority gave their personal time and knowledge
because of their abiding concern for safety, scientific credibility, the quality of American industry and the value of
ASNTs mission.
The Nondestructive Testing Handbook also validates the
peer review system and its ability to generate a high quality
product. It's true that manuscripts for the Nondestructive
Testing Handbook arrived in all conditions within a broad
range of accuracy and consistency (one valuable contribution comprised a two inch stack of yellow legal sheets hand'written in what appeared to be lipstick). Yet, without
exception, the positive criticism and constructive editing of
the peel' reviewers molded the manuscripts into an accurate
and practical finished product.
The international stature of the Nondestructive Testing
Handbook is reflected in its frequent citation in technical
articles written and published in many other countries. One
of the consistent themes in developing each volume was
maintenance of the series' international value. Using SI as
the primary measurement system was one result of this
focus, as was recruitment efforts for authors and reviewers
outside the United States. This international emphasis
allowed the Nondestructive Testing Handbook to be written
and reviewed by British, Canadian, Dutch, French, German,
Greek, Japanese, Saudi Arabian and American volunteers.
Because of these skilled, high-reaching efforts, it turned
out that the second edition also showed how interesting
nondestructive testing can be. There are uses of the technology documented for virtually every industry and an
astonishing range of materials. Here you can read about
microwaving the pyramids (Vol. 4, P 546), listening to integrated circuit chips cracked in their substrates (VoL 5.,
p 358), using alternating current underwater to do magnetic
particle tests (VoL 6, p384), or applying ultrasonic waves to
inspect the human abdomen and-other kinds of plumbing
(Vol. 7, P 822 and 585). It's an impressive range of data for a
handbook series.
Handbooks are expected to document the uses of their
technology and this field guide function may be supported
by text that details the pure science behind the applications.
The second edition of the Nondestructive Testing Handbook
does both of these things well, while at the same time representing the dedication of its volunteer contributors, the
value of the peer review system and the importance of its
international scope. With the publication of this, the second
editions tenth and final volume, ASNT can rightly claim to
have documented a critical technology.
Thanks are due to Jack McElhaney, who helped in word
processing of much of the text, to Edwards Brothers for
printing and binding, to Kevin Mulrooney for indexing and
to Hollis Humphries-Black, who prepared the art and layout
and made good things happen at every stage of production.
Thanks are due especially to Technical Editors Stanley
Ness and, Charles Sherlock for overseeing the technical
review. The use of metric units in the text was reviewed hv
Holger H. Streckert and Stanislav L [akuba, All the man)'
volunteer contributors and reviewers deserve congratulations for what they have accomplished.
Paul Mclntire
Patrick Moore
Editors
v
I
]
1
J
II
II
II
ACKNOWLEDGMENTS
11
"11
1\
Nondestructive testing (NDT) continues to become
more important in this age of increasing high technology.
Materials with compositions of greater sophistication for
higher tensile strengths at lighter weights create the need
for NDT to be performed at higher sensitivities with more
accuracy and more predictability than ever before. Continued public demands for safer products at lower cost also
increase the need for better and more reliable NDT The
development of miniaturized computer chips and integrated circuits with power unthinkable just a few decades
ago has, in tum, spurred development of electronic NDT
equipment and helped create new NDT techniques. This
advancing technology and the need for increased sophistication in NDT methods promote each other. The results are
observed every day in the more reliable and safer materials
and products used in the home, in automobiles, in aircraft
and the space program.
Volume 10 of the Nondestructive Testing Handbook contains an overview of each of the major NDT methods widely
used by industry. In a single cover, Nondestructive Testing
Overview provides students with an introductory text and
management with a readily portable reference publication.
It provides NDT and quality assurance managers with general howledge and direction to ensure the specification of
the most effective NDT for manufacturing and for in-service inspection of existing structures. Volume 10 will prove
valuable to NDT practitioners whose work is limited to one
or two NDT methods but who must have a working familiarity with other methods, without requiring a separate volume for each.
The second edition of AS:-H's Nondestructice Testing
Handbook compiles the knowledge of many volunteers
within the NDT communitv, both within and outside ASl\T.
Single NDT method volu;nes require the input of many
within that single NDT discipline. However, because Volume 10 covers all the major NDT methods, it required the
dedication and voluntarv time and hard work of volunteers
throughout all the NDT disciplines. The follov,ing acknowledgments indicate some of the hundreds of individuals and
organizations that contributed indirectly to the preparation
of this book As technical co-editors, we thank all those who
contributed to this volume as writers and reviewers.
Volume 10 of the Nondestructive Testing Handbook draws
extensively from the preceding nine volumes of the second
edition. Volunteers who were most active in the compilation
of this volume are listed on the title page to each section.
Additionally, the list of contributors below acknowledges contributors to the original sections in the second edition volumes from which Volume 10 was compiled. The reviewers
listed after the contributors below, however, are those who
participated in the preparation of Volume 10, not necessarily
other volumes in the second edition,
To acknowledge the support of scholarship by industry, a
name of a contributor or reviewer is followed by his or her
affiliation at the time of most recent activity for the Nondestructive Testing Handbook, even though that person may
have changed employers since. Apologies are extended to
contributors, reviewers and others who helped to create this
volume but may have been omitted from the list below.
Handbook Development
Committee
Sreenivas Alampalli, New York State Department of
Transportation
Michael W, Allgaier, GPU Nuclear
Robert A. Baker, Pennsylvania Power & Light Company
Albert S. Birks, AKZO Nobel Chemicals
Richard H. Bossi, Boeing Defense and Space Group
Lawrence E. 'Bryant, [r., Los Alamos National Laboratorv
John Stephen C~rgilI, Pratt & Whitney
,
William C. Chedister, Circle Chemical Company
William D. Chevalier, Zetec, Incorporated
James L. Doyle, Quest Integrated, -Incorporated
Matthew J. Golis
Allen T. Green, Acoustic Technology Group
Robert E. Green. [r., Johns Hopkins University
Grover Hardv, Materials Directorate of Wright Laboratorv
.
~
James F. Jackson
Stanislav I. Ja~llba, 51 [akub Associates
John K. Keve, Westinghouse Hanford
Irvin R. Kraska. Martin Marietta
Llovd P. Lemle, Jr.
Rennie K. Miller. Physical Acoustics Corporation
Scott D. Miller, Aptech Engineering Services
Philip A. Oikle. Yankee Atomic Electric Company
Stanlev :\ess
Rona!t! T. Nisbet
Stanlev Ness
Charles N. Sherlock
Technical Editors
vi
Timothy J. Fowler, Felicity Group, Incorporated
.
Matthew J. Golis
Allen T. Green, Acoustic TechnologyGroup
Robert E. Green, Jr., Johns Hopkins University
Paul E. Grover, Infraspection Institute
Donald J. Hagemaier, McDonnell Douglas Aerospace
Grover Hardy, Materials Directorate of 'Wright Laboratory
E.G. Henneke, II, Virginia Polytechnic and State
University
Nathan Ida, Akron University
Frank A. Iddings
[amesF, Jackson
Stanislav L Jakuba, SI Jakub Associates
Thomas S. Jones, Industrial Quality, Incorporated
John K. Keve, Westinghouse Hanford
Irvin R. Kraska, Martin Marietta
David S. Kupperman, Argonne National Laboratory
Ronnie K. Miller, Physical Acoustics Corporation
Scott D. Miller, Aptech Engineering Services
Ronald T. Nisbet, Ronan Corporation
Philip A. Oikle, Yankee Atomic
Emmanuel P. Papadakis, Quality Systems Concepts
Morteza Safar, Q-uest Integrated, Incorporated
Ram P. Samy, The Timken Company
Edward R. Schaufler, Infra Red Scanning Services
J. Thomas Schmidt, J. Thomas Schmidt Associates
Paul B. Shaw, Chicago Bridge and Iron, Incorporated
Amos G. Sherwin, Sherwin NDT Systems
Kermit Skeie, Kermit Skeie Associates
John R. Snell, Jr., John Snell and Associates
Roderic K. Stanley, Quality Tubing, Incorporated
Phil Stolarski, California Department of Transportation
Holger H. Streckert, General Atomics
Colleen M. Stuart, Technicorp
Stuart A. Tison, National Institute of Standards and
Technology
Noel A. Tracy, Universal Technology Corporation
Mark F.A. Warchol, Aluminum Company of America
Randall D. Wasberg, American Society for Nondestructive
Testing
Carl Waterstrat, Varian Vacuum Products
George C. Wheeler, Wheeler NDT, Incorporated
Donald J. Hagemaier, McDonnell Douglas Aerospace
Richard L. Hannah, JF Technologies
E. Blair Henry
Roger F. Johnson, Quest Integrated, Incorporated
Thomas S. Jones, Industrial Quality, Incorporated
Satish Nair, Karta Technology, San Antonio, Texas
Stanley Ness
Daniel Post, Virginia Polytechnic Institute and State
University
Martin]. Sablik, Southwest Research Institute
Cesar A. Sclammarells, Illinois Institute of Technology
Pieter ]. Sevenhuijsen, National Aerospace Laboratory
John R. Snell, [r., John Snell and Associates
Roderic K. Stanley, Quality Tubing, Incorporated
John Scott Steckenrider, Argonne National Laboratory
Peter K. Stein, Stein Engineering Services
Colleen M. Stuart, Technicorp
Walter Tomasulo, Technicorp
Alex Vary, NASA Lewis Research Center
Volume 10 Reviewers
Michael W Allgaier, GPU Nuclear
Robert A. Baker
Yoseph Bar-Cohen, Jet Propulsion Laboratory
Harry Berger, Industrial Quality, Incorporated
Albert S. Birks, AKZO Nobel Chemicals
Bernard Boisvert
Richard H. Bossi, BoeingDefense and Space Group
Ronald J. Botsko, NDT Systems, Incorporated
John Stephen Cargill, Pratt & Whitney
Francis H. Chang, Lockheed Martin Technical Aircraft
Systems
William C. Chedister, Circle Systems, Incorporated
Eugene J. Chemma, Bethlehem Steel Corporation
Thomas F. Drouillard
].C. Duke, Jr., Virginia Polytechnic Institute and State
University
Gary R. Eld~r, Gary Elder & Associates
Todd S. Fleckenstein, Moody International
ix
CONTENTS
SECTION 1: INTRODUCTION TO
NONDESTRUCTIVE TESTING
PART 1: NATURE OF NONDESTRUCTIVE
TESTING
.
Definition of Nondestructive Testing
..
Purposes of Nondestructive Testing
.
Rapid Growth and Acceptance of
Nondestructive Tests . . . . . . . . . . . . . . . . .
PART 2: QUALITY ASSURANCE
.
Basic Concepts of Quality Assurance
.
Quality Control and Quality Assurance
.
Establishing Quality Levels
.
PART 3: TEST SPECIFICATION
.
Management Policies
.
Sources of Information
.
SpecifYing Sensitivity and Accuracy in Tests ..
Establishing the Reliability.of Tests
.
Scheduling Tests for Maximum
Effectiveness and Economy
.
Applications of Nondestructive Testing
.
Mode of Presentation
~
.
PART 4: UNITS OF MEASURE FOR
NONDESTRUCTIVE TESTING
.
Origin and Use of the SI System
.
SI Units for Radiography
.
Fundamental S1 Units Used for Leak testing ..
SI Units for Electrical and Magnetic Testing ..
SI Units for Other Nondestructive TestingMethods
,.
Prefixes for SI Units .. ,
,.
BIBLIOGRAPHY
,,.
SECTION 2: LEAK TESTING
Ensuring System Reliability through Leak
Testing
.
Leak Testing to Detect Material Flaws . .
.
SpecifYing Desired Degrees of Leak
Tightness
.
Avoiding Impractical Specifications for
Leak Tightness
.
SpecifYing Leak Testing Requirements to
Locate Every Leak
.
SpecifYing Sensitivity of Leak Testing for
Practical Applications
.
Definition of Leak Detector and Leak Test
Sensitivity . . . . . . . . . . . . . . . . . . . . . . . . ..
Example of Sensitivity and Difficulty of
Bubble Leak Testing
.
Relation of Test Costs to Sensitivity of
Leak Testing
'.
.
Selection of Specific Leak Testing Technique
for Various Applications
.
Basic Categories of Leak Testing
.
Selection of Tracer Gas Technique for Leak
Location Only
.
Factors Influencing Choice between,
Detector Probe and Tracer Probe Tests ..
Selection of Technique for Leakage
Measurement
.
Practical Measurement of Leakage Rates with
Gaseous Tracers
.
Leakage Measurements of Open Test Objects
Accessible on Both Sides
.
Selection of Test Methods for Systems
Leaking to Atmospheric Pressure
.
Purposes of Leak Testing to Locate
.
Individual Leaks
Classification of Methods for Locating and
Evaluating Individual Leaks
.
Techniques for Locating Leaks 'With
Electronic Detector Instruments
.
Coordinating Overall Leakage Measurements
with Leak Location Tests
,
.
Laser Based Leak Imaging
.
Training of Leak Testing Personnel
.
PART 2: SAFETY 11'\ LEAK TESTING
.
General Safety Procedures for Test Personnel
PsvchologicalFactors and the Safety Program
Control of Hazards from Airborne Toxic
Liquids. Vapors and Particles .""""
Control of Hazards of Flammable Liquids
and Vapors
'
.
I
.
PART 1: MANAGEMENT A1'\D APPLICATIONS
OF LEAK TESTING
,
,.
Functions of Leak Testing
,
,
Relationship of Leak Testing to Product
Serviceability
. ,
,
.
Determination of Overall Leakage Rates
through Pressure Boundaries
,
,
Measuring Leakage Rates to Characterize
Individual Leaks
"
'
.
Quantitative Description of Leakage Rates '.
Examples of Practical Units Used Earlier for
Measurement of Leakage
.
Units for Leakage Rates of Vacuum Systems .
2
2
2
6
9
9
9
10
11
11
12
12
14
14
15
15
18
18
18
20
21
21
22
24
25
26
26
26
26
26
27
28
28
x
28
28
29
29
29
30
30
30
32
32
32
34
34
35
36
36
37
38
38
38
38
39
40
42
42
42
43
44
Control of Electrical and Lighting Hazards ..
Safety Precautions with Leak Testing Tracer
Gases. . . . . . . . . .. . . . . . . . . . . . . . . . . . .
Safety Precautions in Pressure and Vacuum
Leak Testing
Safety Precautions with Compressed Gas
Cylinders
.. :.............
PART 3: HALOGEN TRACER GAS
TECHNIQUES AND LEAK DETECTORS ...
Halogen Vapor Tracer Gases and Detectors . .
Pressure Leak Testing with Halogen (Sniffer)
Detector Probe
PART 4: REFERENCE LEAKS
Terminology Applicable to Reference,
Calibrated or Standard Leaks
Classification of Common Types of Calibrated
or Standard Physical Leaks
Modes of Gas Flow through Leaks . . . . . . . . .
PART 5: PRESSURE CHANGE TESTS FOR
MEASURING LEAKAGE RATES...........
Functions of Pressurizing Gases in
Leak Testing
Conversion of Pressure Measurements
to Svsteme Internationale d'Unites
(SI 'Units)
Compressibility of Gaseous and Liquid
Fluids. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pressure Change Tests for Measuring
Leakage Rates in Pressurized Systems . . . .
Pressure Change Tests for Measuring
Leakage in Evacuated Systems
PART 6: LEAK TESTING OF VACUUM
SySTEMS..............................
The Nature of Vacuum . . . . . . . . . . . . . . . . . .
Leak Testing of Vacuum Systems with
Mass Spectrometer Leak Detector
Techniques . . . . . . . . . . . . . . . . . . . . . . . . .
PART 7: BUBBLE LEAK TESTING
". . .
Introduction to Bubble Techniques
Bubble Testing by Liquid Film Application
Technique
,...........
Bubble Testing by the Vacuum Box
Technique .. ,......................
PART 8: HELIUM MASS SPECTROMETER
LEAK TESTING.........................
Basic Techniques for Leak Detection "ith
Helium Tracer Gas
PART 9: ACOUSTIC LEAK TESTING. . . . . . . . . .
Principles of Acoustic: Leak Testing
Instrumentation for Ultrasonic Detection of
Leaks. . . . . . . . . . .
...............
Techniques of Leakage Monitoring with
Multiple Acoustic Emission Sensors .....
44
PART 10: LEAK TESTING OF STORAGE
TANKS
Detection of External Leaks in Underground
Storage Tanks . . . . . . . . . . . . . . . . . . . . . . .
Leak Testing of Aboveground Storage
Tanks with Double Flat Bottoms ..... , . .
Comparison of Quantitative Leak Testing
Techniques '
,.,..
BIBLIOGRAPHY . . . . . . . . . . . . . . . . . . . . . . . . . . .
45
45
47
48
65
65
65
68
71
48
SECTION 3: LIQUID PENETRANT
TESTING..........................
48
49
PART 1: DEFINITION AND PURPOSE OF
LIQUID PENETRANT TESTING
History ",.,.....,.,..........."....
Basic Penetrant Testing Process ,'.........
Reasons for Selecting Liquid Penetrant
Testing . . . . . . . . . . . . . . , : , . , , , ' , . . . . .
Disadvantages and Limitations of Liquid
Penetrant Testing . . . . . . . . . •. . . . . . . . . . .
Equipment Requirements '..............
Personnel Requirements
,......
PART 2: CLASSIFICATIONS OF PENETRANTS.
Classification of Penetrants by Dye Type ....
Classification of Penetrants by Removal
Method
,
',.......
Types of Developers . , , , , , , . . . . . . . . . . . . .
Qualified!Approved Penetrant Materials ....
Sensitivity
,.,...........
PART 3: PENETRANT TESTING PROCESSES. ,
Selection of a Penetrant Material/Process .. ,
Control of a Penetrant Process ... , . . . . . . . .
Advantages and Limitations of Penetrant
Materials and Techniques ... ,.........
Pretesting. Cleaning and Postcleaning .,....
Summary
,
,
,
,,,...
BIBLIOGRt\PHY
,.............
49
49
49
50
50
50
50
50
52
54
54
55
57
57
57
SECTION 4: RADIATION PRINCIPLES
AND SOURCES
58
59
.59
61
61
61
62
xi
75
76
76
76
77
78
79
80
81
81
81
82
83
83
84
84
85
85
86
88
89
,
91
PART 1: ELECTROMAGNETIC RADIATION . . .
The Photon
,....
X-Rays and Gamma Ravs
,."...
Gen~ration ofX-Ravs ~
,..........
PART 2: RADIATION ABSORPTION
'
Categories of Absorption
,........
Absorption of Photons ,
,
,.
Scattering of Photons
"
"....
Attenuation Coefficients of the Elements . . . .
Neutron Irradiation
,
,....
92
92
92
93
95
95
9.5
96
98
98
PART 3: BASIC GENERATOR
CONSTRUCTION .,
,
,.
X-Ray Tubes
,
,...
High Energy Sources
Control Units under 500 keY . . . . . . . . . . . ..
PART 4: X-RAY OPERATING
RECOMMENDATIONS
Baseline Data .,.......................
Selecting a Unit
Tube Warmup
,
" .. , .. ,
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . .,
Electrical Safety
X-Ray Safety
,
,
PART 5: ISOTOPES FOR RADIOGRAPHY .. , . ..
Radioactivity
, . . . . . . . . . . . . . . . ..
Selection of Radiographic Sources
PART 6: SOURCE HANDLING EQUIPMENT ..
Requirements .. ,
,
Classification . . . . . . . . . . . . . . . . . . . . . . . . ..
Manual Manipulation of Sources
Remote Handling Equipment
Safety Considerations
, . . . . . . ..
BIBLIOGRAPHY
'
, . . . . ..
110
110
110
III
III
112
Il2
114
114
114
120
120
120
120
120
122
129
SECTION 5: FILM RADIOGRAPIIT
131
PART I: FILM EXPOSURE
,.,...
Making a Radiograph
'
'........
Factors Governing Exposure
,.'.,
Geometric Principles ,.,
,
,...
Relations of Milliamperage (Source
Strength), Distance and Time
The Reciprocity Law
'
,
Exposure Factor .. , . '
, .. ,
Determination of Exposure Factors
Contrast ... '.........................
Choice of Film
'
'
Radiographic Sensitivity ..'
,'
''
'.
PART 2: ABSORPTION AND SCATTERING
Radiation Absorption in the Specimen '
"
Scattered Radiation. . . . . . . . . . . . . . . . . . . ..
Reduction of Scatter . '
,'
, . , , . ..
Mottling Caused by X-ray Diffraction
,
Scattering in High Voltage Megavolt
Radiography
,
,.
PART 3: RADIOGRAPHIC SCREENS,
' . '.
Functions of Screens .,
, .. '........
Lead Foil Screens
, .. '
',
' . ..
Fluorescent Screens .. ,
'.,
,
PART 4: INDUSTRIAL RADIOGRAPHIC FILMS,
Selection of Films for Industrial Radiography.
Photographic Density ,
'
'
, . . ..
Densitometers
,
"...
X-Ray Exposure Charts, ,
" ., .. , ... '
132
132
133
134
Gamma Ray Exposure Charts
,
The Characteristic Curve
PART 5: RADIOGRAPHIC IMAGE QUALITY
AND DETAIL VISIBILITY .,
,.......
Controlling Factors
,
Subject Contrast
,
,
Film Contrast
. . . . . . . . . . . . . . . . . . . . ..
Film Graininess and Screen Mottle
Penetrameters . . . . . . . . . . . . . . . . . . . . . . . ..
Viewing and Interpreting Radiographs. . . . ..
PART 6: FILM HANDLING AND STORAGE
IdentifYing Radiographs
Shipping of Unprocessed Films .. '........
Storage of Unprocessed Film
,
,
Storage of Exposed and Processed Film
,
99
99
103
108
161
161
164
164
164
164
166
166
169
170
170
170
170
171
SECTION 6: RADIOSCOPY AND
TOMOGRAPIIT . . . . . . . . . . . . . . . . . . . .. 173
PART 1: FUNDAMENTALS OF RADIOSCOPY..
Principles
,
,..................
Background
, . . . . . . . . . . . . . ..
Basic Technique .,...............'...,.
Recommended Practice
Image Intensifiers
'.'
'
Spectral Matching
,
Statistics
Television Cameras, Image Tubes and
Peripherals. . . . . . . . . . . . . . . . . . . . . . . ..
Optical Coupling
, .,
Viewing and Recording Systems
, . . . ..
PART 2: RADIOSCOPIC IMAGE
ENHANCEMENT '"
,
'
Digital Techniques
Pseudocolor ,
'., .. ',..............
Other Techniques
' ... ' . ' ..... ' . . . ..
PART 3: X-RAY COMPUTED TOMOGRAPHY . "
Introduction
,
Computed Tomography Systems .,
'....
Computed Tomography Applications
, .. ,
139
140
141
141
142
142
143
144
144
146
146
151
174
174
174
175
175
175
177
178
178
182
183
184
184
187
187
188
188
191
195
SECTION 7: ELECTROMAGNETIC TESTING 199
PART 1: INTRODUCTION TO
ELECTROMAGNETIC TESTING . '
"
Typical Uses of Eddv Current
• Nondestructive Tests. . . . . . . . . . . . . . . ..
Method of Induction of Eddv Currents in
Materials ' ..... , .. ,. ,'. , ' ... ' , ... , .'
Test Material Properties Influencing Eddy
Current Tests . ' ' ... ' .... ' ... ,. ."..
Methods for Detection of Eddv Current
Intensities and Flow Patteri'ls
'.
Analysis of Eddy Current Test Signals
(Amplitudes and Phase Angles) ,
"
151
152
152
152
154
157
158
158
158
159
xii
200
200
200
200
201
201
Selection of Optimum Eddy Current Test
Frequencies
'"
Control of Eddy Current Penetration
Depths in Test Materials
Limitations of Eddy Current Tests
Correlation of Eddy Current Test
Indications with Material Properties and
Discontinuities
:.
Typical Industrial Applications of Eddy
Current Tests . . . . . . . . . . . . . . . . . . . . . ..
Eddy Current Transducers
,
Factors Affecting Eddy Current Transducers.
PART 2: REMOTE FIELD LOW FREQUENCY
EDDY CURRENT INSPECTION . . . . . . . . . ..
Remote Field Zone . . . . . . . . . . . . . . . . . . . ..
Eddy Currents in Pipe Wall Applications . . ..
Example Applications . . . . . . . . . . . . . . . . . ..
Conclusions
~. . . . . . . . . . . . . . . . . . ..
PART 3: ELECTROMAGNETIC SORTING
TECHNIQUES . . . . . . . . . . . . . . . . . . . . . . . . ..
Eddy Current Impedance Plane Analysis . . ..
Impedance Plane
Liftoff and Edge Effects on Impedance
Plane
-. . . . . . . . . . ..
Conductivity and Permeability Loci on
Impedance Plane . . . . . . . . . . . . . . . . . . ..
PART 4: EDDY CURRENT APPLICATIONS IN
THE STEEL INDUSTRY. .. . . . . . . . . . . . . . . ..
Eddy Current Systems That Rotate the
Product at Ambient Temperatures
Eddv Current SYstems That Rotate the
Sensors . . . .'. . . . . . . . . . . . . . . . . . . . . . ..
Tests at Elevated Temperatures
PART 5: EDDY CURRENT INSPECTION OF
BOLT HOLES. . . . . . . . . . . . . . . . . . . . . . . . . ..
Eddy Current Bolt Hole Inspection . . . . . . ..
Reference Standards for Bolt Hole Inspection.
Procedure for Bolt Hole Inspection
Automated Bolt Hole Inspection
PART 6: AUTOMOTrVE APPLICATIONS OF
EDDY CURRENT TESTING
Hardness and Case Depth Inspection of
Axle Shafts . . . . . . . . . . . . . . . . . . . . . . . ..
Crack and Porosity Detection and
Machined Hol~ Presence in Master
Brake Cylinders . . . . . . . . . . . . . . . . . . . ..
Tin Plate Thickness on Diesel Engine Piston.
Cold Headed Pinion Gear Blank Crack
Detection . . . . . . . . . . . . . . . . . . . . . . . . ..
Hub and Spindle Hardness and Case Depth
Inspection
Camshaft Heat Treat Inspection . . . . . . . . .
PART 7: MULTIFREQUENCY TESTING. . . . . ..
Requirements for Multifrequency Testing '"
Physical Basis of the Multifrequency Process.
PART 8: MAGNETIC FLUX LEAKAGE
TESTING
Types of Parts Inspected by Magnetic Flux
Leakage
. . . . . . . . . . . . . . . ..
Types of Discontinuities Found by
Magnetic Flux Leakage
Effects of Discontinuities
. . . . . ..
Sensors Used in Magnetic Flux Leakage
Inspection
Typical Magnetic Flux Leakage Applications ..
BIBLIOGRAPHY
"
201
202
202
202
202
203
204
242
242
245
246
246
250
256
SECTION 8: MAGNETIC PARTICLE
206
206
207
208
211
TESTING .........•.......•..•.... , 257
PART I: INTRODUCTION. . . . . . . . . . . . . . . . . ..
Capabilities and Limitations of Magnetic
Particle Techniques . . . . . . . . . . . . . . . . . . . ..
Principles of Magnetic Particle Testing. . . . ..
PART 2: FABRICATION PROCESSES AND
MAGNETIC PARTICLE TEST
APPLICATION
Basic Ferromagnetic Materials Production. ..
Inherent Discontinuities
Primary Processing Discontinuities
Forging Discontinuities
Casting Discontinuities
: . . . . . . . . . ..
Weldment Discontinuities
Manufacturing and Fabrication
Discontinuities . . . . . . . . . . . . . . . . . . . . ..
Service Discontinuities . . . . . . . . . . . . . . . . ..
Corrosion
PART 3: MAGNETIC FIELD THEORY
Magnetic Domains
Magnetic Poles .. . . . . . . . . . . . . . . . . . . . . ..
Types of Magnetic Materials . . . . . . . . . . . . ..
Sources of Magnetism . . . . . . . . . . . . . . . . . ..
PART 4: MAGNETIC FLUX AND FLUX
LEAKAGE
Circular Magnetic Fields
Longitudinal Magnetization
Magnetic Field Strength . . . . . . . . . . . . . . . ..
Subsurface Discontinuities . . . . . . . . . . . . . ..
Effect of Discontinuity Orientation
Formation of Indications
PART 5: ELECTRICALLY INDUCED
MAGNETISM. . . . . . . . . . . . . . . . . . . . . . . . . ..
Circular Magnetization . . . . . . . . . . . . . . . . ..
Magnetic Field Direction
. . . . . . ..
Longitudinal Magnetization
Multidirectional Magnetization. . . . . . . . . .. ..
PART 6: MAGNETIC PARTICLE TEST
SYSTEMS
Stationary Magnetic Particle Test Systems .,.
Power Packs
212
212
212
213
213
218
218
222
223
228
228
229
230
231
232
232
234
235
235
236
237
239
239
239
xiii
258
258
258
259
259
259
260
262
263
263
263
266
266
267
267
267
268
268
270
270
270
271
271
272
272
273
273
273
274
275
276
277
277
Mobile and Portable Testing Units,
,
'
,
,
,..
Prods and Yokes .,
PART 7: FERROMAGNETIC MATERIAL
CHARACTERISTICS
,
,.
Magnetic Flux and Units of Measure . . . . . ..
Magnetic Hysteresis .......,............
Magnetic Permeability
,..........
PART 8: TYPES OF MAGNETIZING CURRENT.
Alternating Current
,.............
Half-Wave Direct Current
Full-Wave Direct Current
,.......
Three-Phase Full-Wave Direct Current .... ,
PART 9: DEMAGNETIZATION PROCEDURES.
Justification for Demagnetizing
,....
Methods of Demagnenzanon
,
"
Demagnetization Practices .. . , . . . . . . . . . .,
PART 10: MEDIA AND PROCESSES IN
MAGNETIC PARTICLE TESTING
,..
Magnetic Particle Properties , ... ,'.......
Effects of Particle Size ,..,....,..........
Effect of Particle Shape
,.......
Visibility and Contrast. . . . . . . . . . . . . . .. . . ..
Particle Mobility
, . . . . . . . . ..
Media Selection .. ,....................
Magnetic Particle Testing Processes .. ,....
Conclusion
,
,..
BIBLIOGRAPHY
,
, . . . . . ..
SECTION 9: ACOUSTIC EMISSION
TESTING . . . . . . . . . . . . . . . . . . • . . . . . ..
J
PART 1: FUNDAMENTALS OF ACOUSTIC
EMISSION TESTING , ... , ... ,...........
The Acoustic Emission Phenomenon . . . . . .
Acoustic Emission Nondestructive Testing. ..
Application of Acoustic Emission Tests .....
Successful Applications .... , . . . . . . . . . . . ..
Acoustic Emission Testing Equipment . . . . ..
Microcomputers in Acoustic Emission
Test Svstems
Characteristics of Acoustic Emission
Techniques
"
Acoustic Emission Test Sensitivity
Interpretation of Test Data
'
,
,
The Kaiser Effect .,
"
PART 2: BUCKET TRUCK AND LIFT
INSPECTION
, . . ..
Acoustic Emission Inspection Development .
Instrumentation for Bucket Truck Inspection.
Test Procedure for Bucket Truck Inspection .
T:pical Test Data
,...............
Acceptance Criteria
PART 3: ACOUSTIC EMISSIO\, TESTS OF
FIBER REINFORCED PLASTIC VESSELS ..
Testing Procedures for Pressure, Storage
and Vacuum Vessels ,
,
, . . . ..
Applications in the Chemical Industries
. ..
Composite Pipe Testing Applications
,
Effect of Acoustic Emission Tests of Fiber
Reinforced Plastic Structures .,........
Zone Location in Fiber Reinforced Plastics ,.
Felicity Effect in Fiber Reinforced Plastics ..
Acceptance of Acoustic Emission Techniques
for Testing of Fiber Reinforced Plastics ,.
PART 4: INDUSTRIAL GAS TRAILER TUBE
APPLICATIONS
"
Recertification of Gas Trailer Tubing . . . . . ..
Test Procedure for Trailer Tubing Tests .....
Advantages of Acoustic Emission Testing of
Trailer Tubes
,
,
,..
PART 5: RESISTANCE SPOT WELD TESTING .
Resistance Spot Welding
,
,.
Principles of Acoustic Emission Weld
Monitoring
,
Weld Quality Parameters That Produce
Acoustic Emission .. ,................
Acoustic Emission Instrumentation for
Resistance Spot Welding
, . . . . . ..
Typical Applications of the Acoustic
,
,.
Emission Method. ,
Monitoring Coated Steel Alternating Current
Welds.............
Alternating Current Spot Welding
Galvanized Steel
Detecting the Size of Adjacent Alternating
Current Welds
,"
Control of Spot Weld Nugget Size .. . . . . . ..
,.
Conclusions
:.,
PART 6: ACOUSTIC EMISSION APPLICATIONS
IN UNDERSEA REPEATER
MANUFACTURE
,
, . . . . . . . . . . . ..
High Voltage Capacitor in the Repeater
Circuitry Unit ,
,..............
Instrumentation and Analvsis
..
Tubulation Pinchweld on the Repeater
Housing
,
, .. "
BIBLIOGRAPHY
,
, . . . . ..
277
278
278
278
278
280
281
281
281
282
282
284
284
284
286
288
288
289
289
290
290
291
291
292
294
297
298
298
298
300
300
301
302
302
303
303
310
310
312
314
314
316
317
318
318
319
321
322
322
323
324
324
326
327
327
329
329
330
331
331
332
334
339
SECTION 10: INTRODUCTION TO
ULTRASONIC TESTING . . . . . . . . .. . . . .. 345
304
PART 1: BASIC ULTRASONIC TESTING
Advantages of Ultrasonic Tests
,.
Limitati~ns of Ultrasonic Tests
"
Criteria for Successful Testing
PART 2; ULTRASONIC WAVES IK ~IATERIALS.
Definition of Wave and Wave Properties ....
Ultrasonic Attenuation ,
,.............
Nonlinear Elastic Waves
, ..
30.5
30,5
306
307
308
309
310
xiv
346
346
347
348
:349
350
3.50
350
PART 3: IMPLEMENTATION OF ULTRASONIC
TESTING
Transmission and Reflection Techniques
Ultrasonic Test Systems
Ultrasonic Sources
Typical Transducer Characteristics . . . . . . . ..
Through-Transmission Systems . . . . . . . . . . ..
Pitch and Catch Contact Testing
Amplitude and Transit Time Systems . . . . . ..
B-Scan Presentation
C-Scan Presentation
. . . . . . . . . . . . . . ..
System Calibration
'
Major System Parameters
PART 4: ULTRASONIC TESTING EQUIPMENT.
Basic Ultrasonic Test Systems . . . . . . . . . . . ..
Portable Instruments
Capabilities of General Purpose Ultrasonic
Test Equipment . . . . . . . . . . . . . . . . . . . ..
Modular Ultrasonic Equipment
Special Purpose Ultrasonic Equipment
Operation in Large Testing Systems . . . . . . ..
PART 5: OTHER ULTRASONIC TECHNIQUES.
Optical Generation and Detection of
Ultrasound . . . . . . . . . . . . . . . . . . . . . . . ..
Optical Generation of Elastic Waves
Optical Detection of Ultrasound.
Future Developments in Laser Ultrasonics ..
Air Coupled Transducers .
Low Frequency Transducers
High Frequency Transducers
Electromagnetic Acoustic Transducers . . . . ..
BIBLIOGRAPHY. . . . . . . . . . . . . . . . . . . . . . . . . ..
351
351
351
352
353
354
354
356
358
359
359
361
363
363
364
367
367
368
369
370
370
370
370
371
371
371
372
373
378
SECTION 11: ULTRASONIC PULSE ECHO
TECHNIQUES. . . . . . . . . . . . . . . . . . . . .. 379
PART 1; ULTRASONIC TESTING
TECHNIQUES . . . . . . . . . . . . . . . . . . . . . . . . ..
The A-Scan Method
The B-Scan Method
. . . . . . . . . . . . . ..
The C-Scan Method .. . . . . . . . . . . . . . . . . ..
PART 2: STRAIGHT BEAM PULSE ECHO
TESTS. . .
Instrumentation for Straight Beam Tests
Straight Beam Test Procedures. . . . . . . . . . ..
Applications of Straight Beam Contact Tests.
Discontinuity Discrimination
Discontinuities Detected by the Straight
Beam Method
.
~. . . . . ..
Sizing Discontinuities . . . . . . . . . . . . . . . . . ..
Mechanical Scanning
Selection of Ultraso~ic Test Frequencies
Effects of Ultrasonic Transducer Diameter ..
Transducer Near Field
380
380
380
380
:382
382
382
:384
:38.5
386
386
3Ell)
388
388
389
Divergence of Ultrasonic Beams in the
Far Field
Focused Beam Immersion Techniques. . . . ..
Ultrasonic Beam Attenuation by Scattering ..
Selection of Test Frequencies . . . . . . . . . . . ..
Effect of Discontinuity Orientation on
Signal Amplitude
Effect of Geometry of Discontinuity on Echo
Signal Amplitude
"
Data Presentation . . " . . . . . . . . . . . . . . . . ..
Tests of Multilayered Structures and
Composites
Dual-Transducer Methods
PART 3: ANGLE BEAM CONTACT TESTING. "
Verification of Shear Wave Angle
Ranging in Shear Wave Tests. . . . . . . . . . . ..
Ultrasonic Tests of Tubes
Weld Testing . . . . . . . . . . . . . . . . . . . . . . . . ..
PART 4: COUPLING MEDIA FOR
CONTACT TESTS
Use of Transducer Shoes
Use of Couplant and Membranes . . . . . . . . ..
Use of Delay Lines
Selection and Use of Coupling Media
Selection of Couplants
Operator Techniques to Ensure Good
- Coupling
PART 5: IMAGING OF PULSE ECHO
CONTACT TESTS
Ultrasonic Imaging Procedures . . . . . . . . . . ..
Contact Weld Tesis . . . . . . . . . . . . . . . . . . . ..
PART 6: ULTRASONIC PULSE ECHO WATER
COUPLED TECHNIQUES . . . . . . . . . . . . . . ..
Immersion Coupling . . . . . . . . . . . . .. .....
Immersion Coupling Devices . . . . . . . . . . . ..
Pulse Echo Immersion Test Parameters . . . ..
Test Indications Requiring Special
Consideration. . . . . . ..
Location of Discontinuities. . . . . . . . . . . . . ..
Grain Site Discontinuities
Interpretation of Indications from Rotor
Wheels. . . . . . . . . . . . . . . . . . . . . . . . . . ..
PART 7: IMMERSION TESTING OF
COMPOSITE MATERIALS . . . . . . . . . . . . . . ..
Discontinuities in Composite Laminates ....
Ultrasonic Testing of Composite Laminates ..
Tests of Composite Tubing . . . . .. . . . . . . . . ..
Laminate Test Indications. . . . . . . . . . . . . .
Conclusion
SECTION 12: VISUAL TESTI:'\1G
PART 1: DESCRIPTION OF VISUAL .AND
OPTICAL TESTS
.'
'
389
390
392
393
394
394
395
395
395
397
397
397
398
398
400
400
400
401
401
402
402
404
404
405
407
407
408
410
411
412
413
414
419
419
419
420
423
423
, 425
426
Luminous Energy Tests
Geometrical Optics . . . . . . . . . . . . . . . . . . . ..
PART 2: VISION AND LIGHT . .
The Physiology ~{s.ight .::::::::::::::::
Vision Acuity . . . . . . . . . . . . . . . . . . . . . . . . ..
Vision Acuity Examinations . . ., . . . . . . . . . . ..
Visual Angle
Color Vision
Fluorescent Materials . . . . . . . . . . . . . . . . . ..
_ _ Safety for Visual and Optical Tests
PART 3: BASIC VISUAL AIDS . . . . . . . . . . . . . . ..
Environmental Factors .. , . . . . . . . . . . . . . ..
Effects of the Test Object . . . . . . . . . . . . . . ..
Magnifiers . . . . . . . . . . . . . . . . . . . . . . . . . . ..
Low Power Microscopes . . . . . . . . . . . . . . . ..
Photographic Techniques for Recording
Visual Test Results . . . . . . . . . .....' . . . ..
Image Enhancement. . . . . . . . . . . . . . . . . . ..
PART 4: BORESCOPES
Fiber Optic Boresoopes
Rigid Boreseopes
Special Purpose Borescopes
. ..
Typical Industrial Borescope Applications ...
Borescope Optical Systems . . . . . . . . . . . . . ..
Borescope Construction
_ ..Photographic Adaptations . . . . . . . . . . . . . . ..
PART 5: VIDEO TECHNOLOGY
Photoelectric Devices
: : : : : : : : : : : : ::
Phctoemissive Devices
Photoconductive Cells or Photodiodes
Photovoltaic Devices . . . . . . . . . . . . . . . . . . ..
Uses of Photoelectric Detectinz and
MeasuringDevices ..... ~.............
Photoelectric Imaging Devices . . . . . . . . . . ..
Video Borescopes
Video Borescope Applications. . . . . . . . . . . ..
Principles of Scanning
Television Camera Tubes
Cathode Ray ViewingTube . . . . . . . . . . . . .
Video Resolution . . . . . . . . . . . . . . . . . . . . . ..
PART 6: REMOTE POSITIOI'\ING AND
TRANSPORT SYSTEMS
Fixed Systems ... :
: : : : : : : : : : : : : : : : .:
Automated Systems
426
426
428
428
429
430
432
432
435
435
440
440
441
443
445
Manual Systems
System Selection and Application . . . . . . . . ..
PART 7: MACHINE VISION TECHNOLOGY ...
Lighting Techniques . . . . . . . . . . . . . . . .. . ..
Optical Filtering. . . . . . . . . . . . . . . . . . . . . ..
Image Sensors. . . . . . . . . . . . . . . . . . .
465
466
468
468
470
470
SECTION 13: THERMOGRAPHY AND
OTHER SPECIAL METHODS •........ 473
PART 1: THE SPECIAL NONDESTRUCTIVE
TESTING METHODS . . . . . . . . . . . . . . . . . . ..
Relationship between Material Property and
Material Behavior
PART 2: PRINCIPLES OF INFRARED
THERMOGRAPHY
Heat Transfer
. . . . . . . . . . . . . . . . . . ..
Instrumentation and Techniques
PART 3: THERMOGRAPHIC APPLICATIONS ..
Composite Materials and Structures . . . . . . ..
Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . ..
Electric Power Distribution and
Transmission Systems
Pavement, Bridge Decks and Subterranean
Surveys
' . . . . . . . . ..
Automotive Applications . . . . . . . . . . . . . . . ..
Bonded Materials and Structures ... . . . . . ..
Diverse Applications . . . . . . . . . . . . . . . . . . ..
PART 4: OPTICAL METHODS
Grid and Moire Nondestructive Testing. . . ..
Holography . . . . . . . . . . . . . . . . . . . . . . . . . ..
Shearography
Point Triangulation Profilometry
PART 5: OTHER SPECIAL METHODS
Alloy Identification
. . . . . . . . . . . . ..
Electromagnetic Special Methods
Acoustic Methods .. . . . . . . . . . . . . . . . . . . ..
Resistance Strain Gaging
446
447
449
449
450
452
452
453
454
455
457
457
457
457
457
458
458
459
461
461
462
462
463
474
475
478
478
482
486
486
490
491
491
492
493
495
497
49i
498
500
500
503
503
503
505
506
SECTION 14: NONDESTRUCTIVE TESTING
GLOSSARy.. . . . . . . . . . . . . . . . . . . . ... 515
46.5
465
465
INDEX
xvi
..............
,.~~
~
.
567
SECTION
INTRODUCT·ION TO
NONDESTRUCTIVE TESTING
1
2 / NONDESTRUCTIVE TESTING OVERVIEW
PART 1
NATURE OF NONDESTRUCTIVE TESTING
Definition of Nondestructive
Testing
Nondestructive testing (NDT) has been defined as comprising those test methods used to examine or ins-pect a part
or material or system without impairing its future usefulness. The term is generally applied to nonmedical investigations of material integrity. . Strictly speaking, this definition of nondestructive testing does include noninvasive medical diagnostics. Xvrays,
ultrasound and endoscopes are used by both medical and
industrial nondestructive testing. In the 1940s, many members of the American Society for Nondestructive Testing
(then the Society for Industrial Radiography) were medical
X-ray professionals. Medical nondestructive testing, however, has come to be treated by a body of learning so separate from industrial nondestructive testing that today most
physicians never use the word nondestructive.
Nondestructive testing is used to investigate specifically
the material integrity of the test object. A number of other
technologies - for instance, radio astronomy, voltage and
amperage measurement and rheometry (flow measurement) - are nondestructive but are not used to evaluate
material properties specifically. Nondestructive testing is
concerned in a practical way with the performance of the
test piece - how long may the piece be used and when does
it need to be checked again? Radar and sonar are classified
as nondestructive testing when used to inspect dams, for
instance, but not when they are used to chart a river bottom.
Nondestructive testing asks "Is there something wrong
with this material?" Various performance and proof tests, in
contrast, ask "Does this component work?" This is the reason that it is not considered nondestructive testing when an
inspector checks a circuit by running electric current
through it. Hydrostatic pressure testing is usually proof testing and intrinsicallv not nondestructive ~ but acoustic: emission testing used to monitor changes in a pressure vessel's
integrity dt!ring hydrostatic testing is nondestructive testing.
Another gray area that invites various interpretations in
deHning non-destructive testing is that of future usefulness.
Some material investigations involve taking a sample of the
inspected part for testing that is inherently destructive. A
noncritical part of a pressure vessel ma>' be scraped or
shaved to get a sample Tor electron microscopy. for example.
Although future usefulness of the vessel is not impaired b>"
the loss of material, the procedure is inherently destructive
and the shaving itself --in one sense the true «test object"
- has been removed from service permanently.
The idea of future usefulness is relevant to the quality
control practice of sampling. Sampling (that is, the use of
less than 100 percent inspection to draw inferences about
the unsampled lots) is nondestructive testing if the tested
sample is returned to service. If the steel is tested to verify
the alloy in some bolts that can then be returned to service,
then the test is nondestructive. In contrast, even if spectroscopy used in the chemical testing of many fluids is
inherently nondestructive, the testing is destructive if the
samples are poured down the drain after testing.
Hardness testing by indentation provides an interesting
test case for the definition of nondestructive testing. Hardness testing machines look somewhat like drill presses. The
applied force is controlled as the bit is lowered to make a
small dent in the surface of the test piece. Then the diameter or depth of the dent is measured. The force applied is
correlated with the dent size to provide a measurement of
surface hardness. The future usefulness of the test piece is
not impaired except in rare cases when a high degree of surface quality is important. However, because the piece's contour is altered, the test is rarely considered nondestructive.
A nondestructive alternative to this hardness test could be
.
to use electromagnetic nondestructive testing.
Nondestructive testing is not confined to crack detection, Other discontinuities include porosity, wall thinning
from corrosion and manv sorts of disbonds. Nondestructive
material characterizatio~ is a grov\ling field concerned with
material properties including material identification and
microstructural characteristics - such as resin curing, case
hardening and stress - that have a direct influence on the
service life of the test object.
Nondestructive testing has also been defined by listing
or dassif}ing the variousmethods, 1.2 This approach is prac"
tical in that it typically highlights methods in use by industry.
Purposes of Nondestructive Testing
Since the 1920s, the art of testing without destroying the
test object has developed from a laboratorv curiosity to an
indispensable tool of production. No longer is visual exarnination of materials, parts and complete products the principal means of determining adequate quality. Nonclestmc:tive
INTRODUCTION TO NONDESTRUCTIVE TESTING I
tests in great variety are in worldwide use to detect variations in -structure, minute changes in surface finish, the
presence of cracks or other physical discontinuities, to measure the thickness of materials and coatings and to determine other characteristics of industrial products. Scientists
and engineers of many countries have contributed greatly to
nondestructive test development and applications.
The various nondestructive testing methods are covered
in detail in the literature but it is always wise to consider
objectives before plunging into the details of a method.
What is the use of nondestructive testing? Why do thousands of industrial concerns buy the testing equipment, pay
the subsequent operating costs of the testing and even
reshape manufacturing processes to fit the needs and findings of nondestructive testing?
Modem nondestructive tests are used by manufacturers
(1) to ensure product integrity, and in turn, reliability; (2) to
avoid failures, prevent accidents and save human life (see
Figs. 1 and 2); (3) to make a profit for the user; (4) to ensure customer satisfaction and maintain the manufacturer's
reputation; (5) to aid in better product design; (6) to control
3
manufacturing processes; (7) to lower manufacturing costs;
(8) to maintain uniform qualitylevel; and (9) to ensure operational readiness.
Ensuring the Integrity/Reliability of a Product
The user of a fabricated product buys it with every
expectation that it will give trouble-free service for a reasonable period of usefulness. Few of today's products are
expected to deliver decades of service but they are required
to give reasonable unfailing value. Year by year the public
has learned to expect better service and longer life, despite
the increasing complexity of our everyday electrical and
mechanical appliances.
America has always been a nation on the move. Today
our railroads, automobiles, buses, aircraft and ships carry
people to more places faster than ever before. And people
expect to get there without delays due to mechanical failure.
Meanwhile factories tum out more products, better, faster
and with more automatic machinery. Management expects
machinery to operate continuously because profits depend
FIGURE 1. Fatigue cracks caused damage to the fuselage of this Aloha Airlines aircraft, causing the
death of a flight attendant and injury to many passengers (April 1988)
4 I NONDESTRUCTIVE TESTING OVERVIEW
on such sustained output. The complexity of present-day
products and the machinery which makes and transports
them requires greater reliability from every part.
If a product has one part that has a probability of failure
of 1 in 1,000 before it has served a reasonable life, it may be
satisfactory. This seems to be a very low chance of failure.
Now suppose that a product is assembled from 100 critical
parts of various kinds and that each part has a failure possibility of 1 in 1,000. 'What then is the possibility of failure of
the assembled item? The overall reliability of any assembly
is the mathematical product of the component reliability
factors. Overall reliability of this example is then:
R
=
0.999 100
'"
0.9057
The possibility of failure of the assembly is then:
(Eq. 1)
1.00 -
0.9057
;;;
0.0943
or almost 1 in 10. It is certain that the user of this product
will be highly dissatisfied if lout of every 10 units fails
prematurely. The point is that component integrity, and in
turn, reliability must be immensely greater than the required
reliabilityof the assembled product.
Consider the ordinary V-8automobile engine. It has only
one crankshaft but eight connecting rods, sixteen valve
springs and hundreds of other parts. Theoretically, failure of
anyone of these could make the motor useless. Yet how frequently does the car owner experience a part failure? This
amazingly low incidence of service failure during the normal
life of an automobile is a great tribute to the ability of the
automotive engineers to design well, of metallurgists to
develop the right materials, of production personnel to cast,
FIGURE 2. Boilers operate with high internal steam pressure; material discontinuities can lead to
sudden, vio'entfallure with possible injury to people and property
FROM BEN BAILEY. USEO WITH PERMISSION.
(Eq.2)
INTRODUCTION TO NONDESTRUCTIVE TESTING I 5
roll, forge, machine and assemble correctly, and of inspectors and quality control staff to set standards and see that
the product meets those standards.
Preventing Accidents and Saving Lives
Ensuring product reliability is necessary because of the
general increase in performance expectancy of the public. A
homeowner expects the refrigerator to remain in uninterrupted service, indefinitely protecting the food investment,
or the power lawnmower to start with one pull of the rope
and to keep cutting grass for years on end. The manufacturer expects the lathe, punch press Or fork lift to stand up
for years of continuous work even under severe loads.
But reliability merely for convenience and profit is not
enough. Reliability to protect human lives is a valuable end
in itself. The railroad axle must not fail at high speed. The
front spindle of the intercity bus must not break on the
curve. The aircraft landing gear must not collapse on touchdown. The mine hoist cable must not snap with people in
the cab. Such critical failures are rare indeed. And this is
mostcertainly not the result of mere good luck. In large part
it is the direct result of the extensive use of nondestructive
testing and of the high order of nondestructive testing ability now available.
Ensuring Customer Satisfaction
While it is true that the most laudable reason for the use
of nondestructive tests is that of safety, it is probably also
true that the most comnwn reason is that of making a profit
for the user. The sources of this profit are both tangrble and
intangible.
Toe intangible source of profit is ensured customer satisfaction. Its corollary is the preservation and improvement of
the manufacturer's reputation. To this obvious advantage
may be added that of maintaining the manufacturer's competitive position. It is generally true that the user sets the
quality level, It is set in the market place when choosing
among the products of several competing manufacturers.
Certainly the manufacturer's reputation for high quality is
only one factor. Others may be function, appearance, packaging, service and price. But in todays highly competitive
markets, actual qualityand reputation for quality stand high
in the consumer's mind.
Aiding in Product Design
Nondestructive testing aids Significantly in better product design. For example, the state of physical soundness as
revealed by such nondestructive tests as radiography, magnetic particle or penetrant inspection of a pilot run of castings often shows the designer that design changes are
needed to produce a sounder casting in an important section. The design may then be improved and the pattern
modified to increase the quality of the product. This example is not academic; it occurs almost daily in many plants.
Somewhat outside the scope of discontinuity detection
are nondestructive tests to determine the direction, amount
and gradient of stresses in mechanical parts, as applied in
the field of experimental stress analysis. These play a very
important part in the design of lighter, stronger,-less costly
and more reliable parts.'
-
Controlling Manufacturing Processes
Control is a basic concept in industry. Engineers, inspectors, operators .and production personnel know the problems of keeping any manufacturing process under control.
The process must he controlled, and the operator must be
trained and supervised. When any element of a manufacturing operation gets out of control, quality of the affected
product is compromised and waste may be produced.
Almostevery nondestructive testing method is applied in
one way or another to assist in process control and so ensure
a direct profit for the manufacturer. As one example of
thousands which could he cited, consider a heat treating
operation. The metallurgist sets up a procedure based on
sound material of a given analysis. One nondestructive test,
applied to all parts or to a few from each batch of parts, tells
whether the chemical analysis of the material is so erratic
that the procedure will fail to produce the desired hardness
or induce cracking. A second test may show when and
where cracking has occurred, Another test may show that
the desired hardness has not been developed. If so, process
variables may be corrected immediately. In these ways, cost
and processing time are saved for the manufacturer.
Lowering Manufacturing Costs
There are many other examples of both actual and
potential cost savings possible through the use of nondestructive tests. Most manufacturers could cut manufacturing costs by deciding where to apply the following cost
reduction principle: A nondestructive test can reduce manufacturing cost when it locates undesirable characteristics of
a material or component at an early stage, thus eliminating
costs offurther processing or assembly. -An example of this
principle is the testing of forging blanks before the forging
operation. The presence of seams, large inclusions or cracks
in the blanks may result in a woefully defective product.
(, I
NONDESTRUCTIVE TESTING
OVE~V1EW
Using such a blank would waste all the labor and forge hammer time involved in forming the material into the product.
Another profit making principle is that a nondestructive
test may save manufacturing cost when it produces desirable
information at lower cost than some other destructive or
nondestructive tests. An example of this principle is the substitution of a magnetic particle nondestructive test for acid
pickling to detect seams or cracks. Asit has in many plants, a
straightforward economic study of comparative costs of the
two methods may show the cost savingadvantage of the nondestructive test over the pickling examination. -
Rapid Growth and Acceptance of
Nondestructive Tests
.
The foregoing tangible and intangible reasons for
widespread profitable use of nondestructive tests are sufficient in themselves. But parallel developments have contributed to their growth and acceptance.
Increased Complexity of Modern Machinery
Maintaining Uniform Quality Level
It seems obvious that improved product quality should
be an invariable aim and result of nondestructive testing.
Yetthis is not always the case, for there is such a thing as too
high a quality level. The true function of testing is to control
and maintain the quality level that engineers or design engineers establish for the particular product and circumstances. Quality conscious engineers and manufacturers
have long recognized that perfection is unattainable and
that even the attempt to achieve perfection in production is
unrealistic and costly Sound management seeks not perfection but pursues excellence in management of workmanship
from order entry to product delivery. The desired quality
level is the one which is most worthwhile, all things considered. Quality below the specified requirement can ruin sales
and reputation. Quality above the specified requirement
can swallow up profits through excessive production and
scrap losses. Management must decide what quality level it
wants to produce and support
Once the quality level has been established, production
and testing personnel should aim to maintain this level and
not to depart from it excessively either toward lower or
higher quality. In blunt language, a nondestructive test does
not improve quality. It can help to establish the quality level
but only management sets the quality standard.1f management wants to make a nearly perfect product or wants at the
other extreme to make junk, then nondestructive tests will
help make what is wanted, no more and no less.
In making a drawing for a part, the designer sets tolerances on dimension and finish. If a drawing specifies a certain dimension as 31.8 mm (1.25 in.) but failsto specify the
tolerance, the machine shop supervisor rejects the drawing
as incomplete or assumes the standard tolerance. In nondestructive testing, a quality tolerance (the tolerance on the
characteristic being determined) or criteria for acceptance
or rejection must also be specified. The lack of appreciation
for this obvious requirement has caused more misunderstanding of nondestructive testing and more objections to
nondestructive tests than any other factor. Perhaps it is the
cause of more confusion than all other factors combined.
Consider the present-day automobile. First, the manual
choke became obsolete. The old rod from the dashboard to
a butterfly valve in the carburetor has been replaced by
more reliable and efficient metered fuel injection. The
mechanically connected brake pedal and brake shoe have
given way to hydraulic and antiloek braking systems. The old
manual windshield wipers are now powered by vacuum Or
electricity and complicated by washer jets and variable
timers. Today's components include complex ventilation,
heating, defrosting and air conditioning systems, power
seats, power actuated windows and sun roofs, expanded
electronics, emission controls, cruise controls, stereo equipment, digital gaging and automatic transmissions. The automobile industry, while carrying design complexity to great
lengths, has also tremendously raised component reliability.
Otherwise, most people would never dare to take their car
from the garage for fear of serious failure.
As an even more startling example of component reliability arithmetic, consider computers. They require complex
microprocessors, chips, resistors, wire connections, counters and other parts whose functioning demands operational
reliability in each component. The automobile and the electronic instrument industries are examples of complexity that
could never have been achieved without parallel advances in
nondestructive testing.
Increased Demand on Machines
Within a lifetime, average speeds of railway passenger
and freight trains have doubled. The speed of commercial
air transport has quintupled. Transonic speeds for rocket
powered missiles and for piloted aircraft are not unusual.
Automobile. bus and truck speeds have increased and their
engines tum twice as fast. Elevators in tall buildings are
fully automatic and much faster. with speeds limited only by
the comfort of the passengers. The stress applied to parts in
these vehicles often increases as the square or cube of the
increased velocitv,
In the interest of greater speed and rising costs of materials, the design engineer is always under pressure to reduce
INTRODUCTION TO NONDESTRUCTIVE TESTING I 7
weight. This can sometimes be done by substituting aluminum or magnesium alloys for steel or iron, but such light
alloyparts are not of the same size or design as those they
replace. The tendency is also to reduce the size. These pressures on the designer have subjected parts of all sorts to
increased stress levels. Even such commonplace objects as
sewing machines, sauce pans and luggage are also lighter
and more heavily loaded than ever before. The stress to be
supported is seldom static. It often fluctuates and reverses
at low or high frequencies. Frequency of stress reversals
increases with the speeds of modem machines and thus
parts tend to fatigue and fail more rapidly.
Another cause of increased stress on modem products is
a reduction in the safety factor. An engineer designs with
certain known loads in mind. On the supposition that materials and workmanship are never perfect, a safety factor of 2,3,
.5 or 10 is applied. Because of other considerations though, a
lower factor is often used, depending on the importance of
lighter weight or reduced cost or risk to consumer.
New demands on machinery have also stimulated the
development and use of new 'materials whose operating
characteristics and performance are not completely known.
These new materials create greater and potentially dangerous problems. As an example, there is a record of an aircraft's being built from an alloy whose work hardening,
notch resistance and fatigue life were not well known. After
relativelyshort periods of service some of these aircraft suffered disastrous failures. Sufficient and proper nondestructive tests could have saved manv lives.
As technology improves and as service requirements
increase, machines are subjected to greater variations and to
wider extremes of all kinds of stress, creating an increasing
demand for stronger materials.
Engineering Demands for Sounder Materials
Another justification for the use of nondestructive tests
is the designer's demand for sounder materials. As size and
weight decrease and the factor of safety is lowered, more
and more emphasis is placed on better raw material control
and higher quality of materials, manufacturing processes
and workmanship.
An interesting fact is that a producer of raw material or
of a finished product frequently does not improve quality or
performance until that improvement is demanded by the
customer. The pressure of the customer is transferred to
implementation .ofimproved design or manufacturing. Nondestructive testing is frequently caned on to deliver this new
qualitv level.
Public Demands for Greater Safety
The demands and expectations of the public for greater
safety are apparent evervwhere, Review the record of the
courts in granting higher and higher awards to injured persons. Consider tne outcry for greater automobile safety, as
evidenced by the required use of auto safety belts and the
demand for air bags, blowout proof tires and antilock braking systems. The publicly supported activities of the
National Safety Council, Underwriters Laboratories, the
Environmental Protection Agency and the Federal Aviation
Administration in the United States, and the work of similar
agencies abroad, are only a few of the ways in which this
demand for safety is expressed. It has been expressed
directly by the many passengers who cancel reservations
immediately following a serious aircraft accident. This
demand for personal safety has been another strong force in
the development of nondestructive tests.
Rising Costs of Failure
Aside from awards to the injured or to estates of the
deceased, consider briefly other factors in the rising costs of
mechanical failure. These costs are increasing for many reasons. Some important ones are:
L
2.
3.
4.
greater costs of materials and labor;
greater costs of complex parts;
greater costs due to the complexity of assemblies;
greater probability that failure of one part will cause
failure of others, due to overloads;
5. trend to lower factors of safety;
6. probability that the failure a'f one part will damage
other parts of high value; and
I. failure of a part within an automatic production
machine may shut down an entire high speed, integrated, production line. '\.Then production was carried out on many separate machines, the broken one
could be bypassed until repaired. Today, one machine
is tied into the production of several others. Loss of
such production is one of the greatest losses resulting
from part failure.
Responsibilities of Production Personnel and
Inspectors
Labor today often means a machinery operator. Formerly, a laborer in a shop manually made a part and the
work piece received individual attention. Today the laborer
may be just as skilled but the skill is directed toward the
operation of a machine. The machine requires attention
rather than the work piece, Production rates are also higher.
This prevents paying personal attention to individual parts.
Formerly everyone who worked on a part gave it some
sort of inspection. even if cursory. Today that is seldom the
case. Many production operations are covered hy hoods,
8 I NONDESTRUCTIVE TESTING OVERVIEW
FIGURE 3. Industrial organization chart with channels of responsibility for Inspection areas {chart
shows only departments involved with testing or inspection}
!
---------..fI
QUALITY
PRODUCT DESIGN
SPECIFICATIONS
MANUFACTURING
METHODS
CHIEF
INSPECTOR
I
I
I
_ _ J!
PRODUCT
SPECIFICATIONS
SAFETY
ENGINEEr<ING
LEGEND
I ~ Ar<EAS OF INSPECTION UNDER CHIEF INSPECTOR
T ~ A.REAS OF INSPECTION UNDER DEPARTMENT SUPERVISORS
safety devices and other mechanical fixtures so that the
operator scarcely sees the part. This has increased the number of inspectors and size and complexity of jobs (Fig. 3).
They, too, need faster, more definitive and more accurate
test devices. Inspectors have become skilled specialists.
They have progressed far beyond the individual who walked
down .the railroad track tapping car wheels with a hammer,
scarcely knowing the purpose of the job. Today the railroad
wheel is tested by specialists with far greater reliability and
bv infinitely superior means.
~ To me~t demands of their customers, nondestructive
testing specialists, physicists, metallurgists, chemists and
electrical and mechanical engineers continually develop
better and more accurate tests. They find out more about
materials and components than was ever known without
destroying them. And when these scientists produce one
new answer, they find that the user has posed two new problems.
One problem with increased use of nondestructive testing is that some people think of nondestructive testing as a
panacea. However, unless engineers design products that
can be inspected, nondestructive testing will not be helpful.
Nondestructive testing engine~rs must be involved early in
the design process so that later they can provide service the
deSign engineers require and also facilitate the job of the
inspector.
In the 1930s, nondestructive testing, where it had been
heard of at all, was generally considered an ecil. Later it
became a necessary evil. For a number of years now it has
simply been necessary and a great aid in tens of thousands
of shops in a multitude ofindustries. Most importantly, nondestructive testing has saved uncounted thousands of lives.
INTRODurnON TO NONDESTRUCTIVE TESTING / 9
PART 2
QUALITY ASSURANCE
Basic Concepts of Quality
Assurance
To avoid misunderstanding, it is important to discuss the
meaning, interrelation and interpretation of some widely
used expressions. It is not uncommon to think of inspection
as a nonproductive operation. As such, it is viewed as less
valuable than direct labor. Again, it is not uncommon to
think of testing as a laboratory operation, comparable to
pulling of tensile test bars to determine physical properties.
It is sometimes imagined that quality is something injected
into a product by the qesigner.
In certain situations, these concepts may be true or partiallv true. Actuallv these terms have little real meaning
unl~ss their place in the overall scheme of production and
use of a product is understood.
Product Reliability
First and foremost, the goal for any product is a useful
life. This may be termed reliability, quality (usually meaning
high quality), good value, performance and so on. Consider
the word reliability. The maker of the product generally
agrees that it should be reliable. But how reliable? That
answer is the manufacturer's responsibility. The degree of
reliability must be defined as closely as possible. The
demands of customers, the reliability of competitive products and the market price of similar products are weighed.
Extensiveexperience and the expert advice of all departments within the organization guide the decision. Finally, a
quality level becomes company policy. H:;1ving set policy, it
is management's responsibility to monitor performance. It
wants assurance that its policy is being followed, It wants to
know that the operation is under control or, if not, where
and how it is out of control. It wants assurance of quality.
Quality Control and Quality
Assurance
Quality assurance is the establishment of a program to
guarantee the desired quality level of <l product [rom raw
materials through fabrication, final assemblv and dolivcrv to
the customer. This is accomplished with judiciousprep;ration of specifications and procedures for material selection,
design control and supplier selection. Surveillance through
audits, in-house process control and quality checkpoints are
also specified by the quality assurance program.
Quality control is the physical and administrative actions
required to ensure compliance with the quality assurance
program. These functions include physical and chemical
tests, where appropriate, as well as nondestructive testing at
appropriate points in the rnanufacturing cycle. Also
included in the quality control function are those administrative actions of documentation needed to establish a
record of all quality procedures and their disposition. This is
a vital element of protection against product liability actions
and could serve as a basis for lower insurance premiums. In
many legal judgments, proof of negligence will often help
establish liability.
Document control and completeness of final documentation packages are functions of quality assurance. This is an
activity that requires constant attention. In major construction projects, there is frequently a considerable time lag
between supplier component nondestructive testing and
customer record review. In one embarrassing case, the vendor radiographs of a valve casting that had been rejected
and scrapped were forwarded to the customer along with
documentation showing that the casting was acceptable.
Fortunately, the vendor's document control was able to verif}, that the Originalcasting had been scrapped and also was
able to produce the radiographs of the acceptable replacement. This example illustrates another vital function of
quality assurance; the followup and disposition of corrective
action.
Quality Assurance
Program
A good quality assurance program consists of five basic
elements.
1. Prevention. A formalized plan is required for design-
ing, for inspectabiIity and for cost effectiveness. This
must be a continuing effort.
2. Control. Documented workmanship standards and
compatible procedures are vital for the training of
production and quality personnel.
:3. Assurance. Establishing quality assurance check
points and a rapid information feedback system can
prevent continuing problems.
4. Corrective action. To effectively implement the feedback system, specialists rapidly assess and implement
the necessary corrective action.
10 I NONDESTRUCTIVE TESTING OVERVIEW
5. Auditing. The quality assurance program must contain provisionsfor unbiased, independent audits of all
aspects of the program, including supplied materials
or components. Audits can be made on either a
scheduled or random basis. Quality supervisors must
have management support to audit anything, any
time and anywhere in the manufacturing cycle and to
initiate timely corrective action.
Ouality Centro:
Seeking quality assurance, management sets up a mechanism for obtaining it, a quality control department. Quality
control is a more inclusive term than testing or inspection.
Notably it implies a responsibility for the control of the
quality of the product. In the older concept, the inspection
department was responsible for checking certain aspects of
the product against given specifications. Such inspection is
only part of quality control. For example, the inspector may
say, "The requirements for hardness (or surface finish, freedom from inclusions, or electrical conductivity) seem very
hard for our suppliers or for our own factory to meet." A
quality controller would then ask, "Is the tight specification
necessary? Can we change it? Can we do it a different way
and yet keep the required quality?" When inspectors think
beyond the specification to the why's and wherefore's, then
they enter into the decision about how to make a product of
the required quality easier, cheaper and better and they may
truly be called quality control engineers.
Establishing Quality Levels
One of the toughest problems of managers and design
engineers is to determine and then to define desired quality
level in any product. This problem has no purely math-ematicalsolution. It is not a problem for the engineer to solvenor
a standard for production personnel to establish. Yetit must
be defined as clearly and as accurately as possible.
Too often management leaves this problem solely to the
design engineer, the inspector or to production, by default.
When that happens, the result is often less profit than
expected. The designer usually wants a higher quality level
than necessary. The inspector often agrees with the designer,
Production usually focuses on producing a predetermined
number of units within a specific time. All are sincere. all
are trying to do a good job but each is affected by different
pressures. What management wants is quality assurance
within a certain range or tolerance. Once that is made clear.
the functions of design, production, inspection and quality
control can take over. In any case, recognition of the customer's stated and implied needs must be considered minimum requirements.
Practical Quality Levels
No product is perfect, whatever that word may mean.
The characteristics of a perfect part, material or product
may be defined, but as knowledge increases, it becomes
necessary to add definitions of more characteristics. Total
perfection is never the true goal of nondestructive testing or
manufacturing. Industry desires a certain quality level
below perfection and will even tolerate some deviation from
that level within an economic tolerance, plus or minus.
Range of Test Sensitivity
Many do not realize the wide range of sensitivitypossible
in each nondestructive test. Radiography may be made
superficial or very sensitive to many minute discontinuities
by variations in X-ray tube voltage, type of film, distance
from the tube to the part and other factors, Magnetic particle test sensitivity varies widely with changes in type and
magnitude of current or with concentration and grade of the
particles themselves. If it is desired to locate grinding cracks
two hundredths of a millimeter deep, it can be done_-On the
other hand, if nothing less than 2.5 mm (0.1 in.) deep is considered important, the test can be made that insensitive.
Ouality Specifications
It should not be inferred that the depth of a discontinuity is a common or desirable specification. It maybe used on
primary or intermediate mill items, such as billets or
semirolled steel, or on manufactured parts in the rough
state where a known amount of surface material is to be
removed after inspection. Most commonly, a specification is
concerned with the direction, location or shape of a discontinuitv in the critical areas. These considerations determine
the importance of a discontinuity in causing the fatigue failures common in mechanical parts of assemblies. Control of
test sensitivity in accordance with such specifications is
practical and should be practiced, For example, \>vith magnetic particle testing. the direction of magnetization, field
strength, bath type, concentration and other factors can
control such sensitivity to desired limits.
INTRODUCTION TO NONDESTRUCTIVE TESTING I 11
PART 3
TEST SPECIFICATION
Management Policies
To achieve the maximum value from any nondestructive
testing operation, it is essential to set up proper policies
regarding its use. These policies include:
L statements of the aims of management for development, management and assessment of quality systems;
2. an organization chart of the entire quality management system;
3. description in chart or word form of the interrelation
among all departments of the company; and
4. establishment of skills needed for each person assigned
responsibility within the quality system.
Objectives of Nondestructive Testing
A statement of the aims for a nondestructive test department may be based on one or more of the previously discussed broad reasons for use of these methods:
L to ensure the reliability of the end product;
2. to save lives or prevent accidents; and
3. to save money for the user.
Such a statement should, however. go into much more
detail to make the wishes of management very clear to all
levels of the organization.
Receiving Inspection
Consider a well integrated metal goods manufacturing
company. It receives raw-material such-asbars, plate, shapes
castings, forgings, fasteners and other forms. It may have a
receiving inspection department. The aims of such an operation may include establishing standards and saving money
for the company by:
1. testing incoming material to ensure that defective
material does not go to the shop;
2. keeping quality records for each supplier and noti£~i"
ing the-purchasing department of the various suppliers' quality perfonnance (the lowest cost supplier on
a per-piece basis may not give the lowest overall cost
if the quality level is much lower than that of a supplier whose piece price is higher);
3. advising the purchasing department to inform suppliers of variations in packing. surface protection or other
means that may reduce discontinuities or costs; and
4. consulting with suppliers' inspection or test personnel on the types of tests or the standards or tolerances
used, to the end that both supplier and purchaser are
fully informed of the quality level required.
This receiving inspector would report to the chief
inspector, as shown on the accompanying organization chart
(Fig. 3). Similar definitions of aims and responsibility are
then set up for inspection operations following parts manufacture, assembly and final tests.
In the function of chief inspector. the head of these operations uses standards furnished by the company. The chief
inspector reports to a quality manager, one of whose functions is aSSisting in setting up realistic, well defined quality
specifications. In some plants with fewer people, the chief
inspector may also act as quality manager by establishing the
specifications. These quality specifications (which include
more than the nondestructive testing standards) must be
drawn up with the cooperation of management, sales, engineering and production, and must be thoroughly understood by purchasing. All departments must agree to them.
Thus Fig. 3 shows a dotted communication line between the
quality manager. chief engineer. chief inspector, plant manager and purchasing agent.
Department of Testing or Inspection
In Fig. 3. the letter T associated with stores. parts manufacturing. tools. maintenance .and the safety engineer indicates such departments may have their own nondestructive
test eqUipment, not under supervision of the chief inspector. A lathe operator may have a micrometer and may periodically check dimensions of the product to keep the
operation within control limits. In the same manner. there
may be a magnetic particle inspection unit in the heat treat
department to ensure control of heating and quenching
operations. That unit may be under direct control of the heat
treat foreman. Other production departments, too, may have
their own test equipment for internal control purposes.
Similarly. in the tool room a penetrant inspection may
ensure that tools are reground or that new carbide tips are
sound and ready for use in the machine shop. Such inspection is commonly placed under the foreman of that department. Also. the maintenance department may have its own
equipment for testing the production machinery in the
plant. The safety engIneer may have similar equipment.
Failure of such equipment may be very dangerous to all
plant personnel.
12 I NONDESTRUCTIVE TESTING OVERVIeW
Management of Inspection
Inspection performed by personnel from departments
such as maintenance or the tool room is managed by the
department manager. Production line inspection functions
are, however, under the chief inspector. These inspections
are in the nature of audits and must be performed by personnel who are not responsible to the operation that is being
audited. Therefore, the chief inspector (or quality manager)
should not report to the plant manager but to a general
executive who may be responsible not only for manufacturing but also for engineering or other operations that have a
broad bearing on the entire company performance. This is
the general manager. In some situations, the title may be
manufacturing manager or president. In this way,the policy
of management may be directly applied to the determination and surveillance of the quality of the product.
acceptability or rejectability, or at least a statement of the
accuracy with which discontinuities must be detected. Furthermore, it is necessary to prove that the properties to be
measured by the nondestructive tests are a reliable means of
detecting discontinuities or of predicting strength or serviceability properties. In the absence of these necessary
data, it is not usually possible to intelligently specify a reliable nondestructive test.
Design Engineer and Stress Engineer
The design engineer and stress engineer should supply
the necessary data on service loads, operating conditions
and the limits of performance acceptability. They should
identify the critically stressed regions of the material and
the probable points and types of failure to be expected in
service.
Peer Contact
Materials or Process Engineer
It is highly desirable for quality control and supervisory
personnel to have contacts both inside and outside the company organization. As has been stated, liaison with engineering and production is essential in the development of
standards.for test methods and the test interpretation. In
addition, frequent contacts with the sales or service departments will bring field reports into consideration so that testing specifications can be adjusted to meet service
conditions.
It is essential that other outside contacts be maintained.
Contacts with customers give excellent information. Contacts with suppliers are also important. A supplier with a
definite understanding of the standards and requirements
of the customer may provide better standards or a less
expensive product.
Last, but alsoimportant, is.peer contact for inspection and
testing personnel of all levels. Attendance and membership
in technical societies such as the American Society for Nondestructive Testing is a valuable method of maintaining such
contacts and working toward better, more accurate and
more valuable quality assurance. Committee E-7 on Nondestructive Testing of the American Society for Testing and
Materials also serves the nondestructive testing field. Many
other technical and industrial societies include committees
and research groups devoted to the application of nondestructive tests in their fields.
The knowledge of the design engineer may be supplemented by destructive tests on critical materials and
components. Determination of the correlation between
(1) strength or serviceability and (2) the discontinuities or
properties measured nondestructively usually requires the
aid of a materials or process engineer. Often an extensive
series of controlled destructive tests is required to prove
that the test indications are a complete and reliable indication of serviceability.
Sources of Information
Special care and caution should be used in speci!)ing the
limits of sensitivity and accuracy required or expected in
nondestructive tests. The sensitivity of every type of non destructive test is limited. Sensitivity adequate for testing of
one part may be totally inadequate for another test object,
or for a more severe service condition on the same part. In
Nondestructive test management engineers require full
information concerning service loads and conditions of use
in order to design or sped!)- a useful nondestructive test for
a particular part. They also need clearly established limits of
Nondestructive Test Engineer
Finally the job of finding a sensitive and reliable method
of measuring the correlated property nondestructively is the
responsibility of the nondestructive test engineer. The nondestructive test program must be the result of working
closely with the customer, the design engineer, the stress
engineer and a materials or process engineer, in addition to
the basic job of designing, developing and applying suitable
nondestructive tests. As a result, nondestructive testing
developments will provide valuable data to design engineers
and manufacturers. The nondestructive test must be a reliable measurement of properties it is designed to measure.
Specifying Sensitivity and Accuracy
in Tests
INTRODUCTION TO NONDESTRUCTIVE TESTING I 13
general, more sensitive tests require more elaborate equipment and cost more. The cost of developing, proving and
applying a suitable nondestructive test must be considered
in each application. Nondestructive tests which cannot be
applied economically in specific applications will usually be
abandoned, even when technically adequate.
Reasonable Tolerances
There are no-simple rules for determining the most economical sensitivity and accuracy of such tests. In some
cases, it is not economical to require that the accuracy of
nondestructive tests exceed the accuracies of the bOWD
number and magnitude of service loads. Similarly, it is not
alwavs economical to exceed the accuracv within which the
deSign assumptions predict true stresses or performance.
Alternatively, it may sometimes be reasonable to limit the
specified test sensitivity to some fraction of the tolerance
limits in strength or serviceability.
Interpretati 0 n Limitati 0 ns
Even well established methods of nondestructive testing
are subject to limitations. Radiography, for example, may
reliably reveal porosity, shrinkage, inclusions, dross and misruns in castings, lack of penetration in welds and similar discontinuities. But few indeed are the cases in which the
actual service life or load for failure can be predicted quantitatively from radiographic testing. This would be difficult
to do even if the parts' were destructively sectioned for
detailed internal visual examination.
Similarly, magnetic particle inspection of ferrous materials reveals surface cracks and discontinuities reliablv, However, there are very few cases in which the fatigue ~trength
or the number of load applications required to produce
fatigue failure can be predicted from these test indications.
However, recognition that a surface crack or stress concentration may lead to premature failure under repeated loading is generally sufficient basis for rejecting the material or
part f~r such s'ervice.
~
Geometric Limitations
In designing. specifying or applying nondestructive tests,
it is important to recogniie certain geometric limitations in
their scope and sensitivity. Some test methods are specifically limited to test objects with reasonably flat or parallel
surfaces, or even to constant thickness sections. Ultrasonic
resonance thickness gaging is naturally limited to walls or
plates with nearly parallel surfaces. in order that echoes may
return to the sensing probe.
A few t}l)es of nondestructive tests arc applicable only to
specirnens of exactly identical geometry. Some electromagnetic induction or eddy. current test devices can onlv
. detect
discontinuities in symmetrical rods or bars of given shape
and diameter.
Accessibility Limitations
Some test methods require access to both sides of the
test specimen. In many tests, the source of the probing
medium is located on one side of the test object and the
detector on the opposite side, such as the X-ray tube (or
gamma ray source) and fUm in through-wall radiography.
. Other methods are designed or can be modified for use
as Single-Side tests. Magnetic particle inspection, ultrasonic
reflection techniques and many liquid penetrant tests may
be performed with Single-side access,
Size and Shape Limitations
Some test methods may be applied to parts of almost any
shape or size. Portable apparatus can be used to examine
large, fixed structures in the field. Other tests involve use of
massive testing units on fixed foundations with limited
maneuverability within a confined testing area. Their use is
limited to test objects that can be brought into the test area
and positioned properly with respect to the test apparatus.
Other tests nave definite thickness limits. Beta-ray thickness gages, for example, can penetrate only Very thin lavers
of m~st materials. Contact probe ultrasoni~pul~e refledtion
tests require sufficient material thickness above discontinuities to permit the pulse from the source to attenuate before
the discontinuity sIgnal returns.
Material Limitations
A few tests are limited to certain kinds of materials. Magnetic particle tests, for example. are useful only with ferromagnetic materials. Thev cannot be used for nonferrous
all~)'s or for nonmagnetic, austenitic stainless steel alloys.
Scanning Limitations
Some nondestructive tests permit large areas or volumes
of the test object to be inspected Simultaneously in a single
e:\.-posure or operation. These produce large area images
(liKe radiography and fluoroscopy) or provide indications-of
the entire ex-posed surface (penetrant tests). Many other
test methods .are essentially point tests or small area tests.
These may require scanning of all small areas suspected of
containing discontinuities. Because thev monitor onlv one
area ofth~ materiaL most sheet or platethickness gages fall
into this catezorv
C>
r'
Limiting the Number of Properties to Be Measured
The number of properties to be measured by nondestructive tests should be limited to those of practical importance
14 I NONDESTRUCTIVE TESTING OVERVIEW
in production or serviceability. For example, for given service conditions, a part can be weakened by several causes,
such as improper material, wrong heat treatment, porosity,
shrinkage, segregation, dross, inclusions, surface cracks,
seams, laps and discontinuities in plating. A single nondestructive test should not be expected to detect and measure
all these diverse properties. Often a separate nondestructive
test is required for each general type of discontinuity.
Similar reasoning is true for inspection of service damage. Corrosion, repeated stressing, wear, impact, surface
destruction and many other factors may contribute to service failures of parts that were originally sound. Usually a
separate test method will be required for each of the different general types and locations of service discontinuities,
Establishing the Reliability of Tests
Most nondestructive tests detect and evaluate discontinuities or determine strength Or serviceability by indirect
procedures. These usually involve the measurement of different hut correlated properties. Nondestructive indication
of the existence, location and extent of a discontinuity is one
thing. Determining the influence of that discontinuity on
the strength or serviceability of the test object is quite
another.
Validity of Test Determinations
The determination of test validity requires good engineering judgment based on adequate service experience or
appropriate destructive tests. Typical specimens, some free
of discontinuities and others containing discontinuities of
each basic type and extent, in each critical location, should
be available for such tests. Acquiring suitable reference
specimens is not easy. In many fields of engineering materials, there is a lack of specific information detailing the influence of material and fabrication discontinuities on strength
or serviceability. The nondestructive test cannot supply that
knowledge. Such information must be obtained from
destructive tests or from operating experience.
Validity of Inspectors' Judgments
The necessary prerequisite for reliability in nondestructive tests is a proven correlation between (I) the properties
actually measured by nondestructive tests and (2) the pres~
enee of discontinuities or the ~lrength and serviceability
properties being predicted from measurements. In situations
where such correlations have not been fullv established or
where several factors influence the relationship. evaluations
based on the experience and judgment of skilled inspectors
become a vitallyimportant feature of the nondestructive test
method. Such correlations are usually implied but are seldom
proved or demonstrated. It is usuallydifficult, costlyand time
consuming to obtain the data necessary to establish these correlations and then to design and develop a reliable nondestructive test method based on those data.
Costs of Inadequate Standards
Failure to demonstrate the reliability of test correlations
before applying and depending on nondestructive tests can
be very costly, In most cases of doubt, inspectors using nondestructive test methods tend to be conservative, particularly in the absence of reliable service data. In many cases,
parts rejected because of discontinuities revealed in nondestructive tests have shown no weakening when subjected to
simulated service tests. The cause of these erroneous judgments are inaccurate, arbitrary inspection standards, established more on the basis of fear or ignorance than on the
basis of careful physical tests.
Skill and Judgments of Inspectors
In evaluating nondestructive test methods, it is necessary
to discriminate between the reliability of the test method
and the reliability of the inspectors' judgments. Lack of specific data, inadequate operating experience, or bad judgment may seriously influence the inspector's conclusions.
This situation mav occur even when the nondestructive test
method provides 'excellent data concerning the condition of
the test object. Consequently it is seldom good economy to
place elaborate and useful nondestructive testing equipment in the hands of unskilled laborers or inspectors With
little inspection experience or poor judgment. The combination of accurate test data 'with good judgment is essential
to the success of the overall testing operati-on.
The criteria the inspector uses to evaluate the test object
data must be developed with consideration of the service to
which the part will be subjected. Full regard for past expertence obtained during operation of similar test objects under
the same service conditions is critical to the success of nondestructive testing.
It may be particularly dangerous, however, if the inspector extrapolates conclusions from one service condition to
new and completely different service conditions. Each case
is specific. Unjustified generalizations can be hazardous in
most applications of nondestructive testing. Adequate eX'Perience, adequate information concerning materials and service conditions and good judgment are essential.
Scheduling Tests for Maximum
Effectiveness and Economy
The scheduling of nondestructive tests often has a critical influence on their cost. effectiveness and overall value.
INTRODUCTION TO NONDESTRUCTIVE TESTING I 15
In production, it often proves most effective to apply nondestructive tests at the earliest possible stage in which the
potential discontinuities are present and detectable. In this
way, potential rejects are eliminated before any further fabrication or handling costs are incurred.
practical limiting importance in production or service. Only
those properties which cannot be more economically or reliably controlled through other methods of process control or
inspection should be reserved for nondestructive testing.
Raw Materials
ApplicatIons of Nondestructive
Testing
It is frequently good practice to inspect raw materials as
they enter the plant: Such inspection may be done by the supplier, an independent laboratory or in the receiving inspection
department. In this wa~ defective raw materials cannot enter
production or assembly areas of the plant where they might
be accidentally mixed into good production lots.
In some cases, discontinuities in raw material mav not be
detectable until· some processing steps have bee'n completed. In these cases, inspection should directly follow the
process step which makes their detection feasible.
Processed Materials
Where processing steps may introduce discontinuities,
inspection can best be applied as soon after processing as
feasible. Where fabrication is costly, it is uneconomical to
leave all inspection to the final, finished product stage.
Here, each rejected unit is in its most expensive state. In
addition, failure to detect rejectable discontinuities at this
point may send a defective unit into service and mav cause a
premature failure, which is far more costly.
.
Materials In Service
The optimum interval between nondestructive tests for
damage in-service varies with the conditions of service and
with the types of discontinuities. This period should be
short enough so that discontinuities not detected at the preceding inspection do not have time to propagate to failure
between inspections. In many types of service, there are
natural locations or periods of time at which inspection can
be made most economically Railroad equipment and airplanes may best be examined at a terminal or when serviced
for their next trip. Good engineering judgment, coupled
with extensive experience, usually is required for establishing an optimum inspection schedule.
Nondestructive testing is a branch of the materials sciences that is concerned with all aspects of the uniformity·,
quality and serviceability of materials and structures. The
science of nondestructive testing incorporates all the technology for detection and measurement of significant properties, including discontinuities, in items ranging from research
specimens to finished hardware and products. Bydefinition,
nondestructive techniques are the means by which materials and structures may be inspected without disruption or
impairment of serviceability. Using nondestructive testing,
internal properties of hidden discontinuities are revealed or
inferred by appropriate techniques.
Nondestructive testing is becoming an increasingly vital
factor in the effective conduct of research, development,
deSign and manufacturing programs. Only with appropriate
use of nondestructive testing techniques can the benefits of
advanced materials science be fullv realized. However, the
information required for apprecia'ting the broad scope of
nondestructive testing is rather widely scattered in a multitude of publications and reports. Tables 1 and 2 summarize
information about nondestructive testing methods arranged
to show their purposes and similarities.
The term method as used here refers to the body of spe·
cialized procedures, techniques and instruments associated
with each nondestructive testing approach. There are usually many techniques or procedures associated with each
method. The following text identifies, classifies and
describes these methods without gi\ing details on application or procedures, thus providing a resume ofeach method
in a single place, for quick reference.
Mode of Presentation
Number of Different Tests
Classification of Methods
It is also usually difficult to answer the question of how
many different nondestructive tests to apply at a particular
time or at a specific stage of service or production. If spe·
ciiic nondestructive tests for each of the potential causes of
failure are combined into large and complex nondestructive
test operations, the costs can be unreasonably high. Consequently the deSigner, materials or process engineer and the
service engineer should determine which properties are of
In a report. the National Materials Advisorv Board
(NMAB) Ad Hoc Committee on Nondestructive Evaluation
adopted a system that classified methods into six major categories: \1SUal. penetrating radiation, magnetic-electrical, me~
chanical vibration, thermal and chenncal-electrochemical.v"
A modified version of the classification system is presented
below. Additional categories have been included to cover new
methods. The resulting classification system is shO\\11 in
J 6 I NONDESTRUCTIVE TESIING OVERVIEW
TABLE 1. Nondestructive testing method categories
Categories
Objectives
Basic Categories
Mechanical-optical
color; cracks; dimensions; film thickness; gaging; reflectivity; strain distribution and magnitude; surface
finish; surface flaws; through-cracks
Penetrating radiation
cracks; density and chemistry variations; elemental distribution; foreign objects; inclusions; micro porosity;
misalignment; missing parts; segregation; service degradation; shrinkage; thickness; voids
Electromagnetic-electronic alloy content; anisotropy; cavities; cold work; local strain. hardness; composition; contamination;
corrosion; cracks; crack depth; crystal structure; electrical and thermal conductivities; flakes; heat
treatment; hot tears; inclusions; ion concentrations; laps; lattice strain; layer thickness; moisture content;
polarization; seams; st";gregation; shrinkage; state of cure; tensile strength; thickness; disbonds
Sonk-ultrasonk
crack inltiaion and propagation; cracks. voids; damping factor; degree of cure; degree of impregnation;
degree of slntering; delaminations; density; dimensions; elastic moduli; grain size; inclusions;
mechanical degradation; misalignment; porosity; radiation degradation; structure of composites; surface
stress; tensile. shear and compressive strength; disbonds; wear
Thermal and infrared
bonding: composition; emissivity: heat contours: plating thickness; porosity; reflectivity; stress; thermal
conductivity; thickness; voids
Chemical-analytical
alloy identification; composition; cracks; elemental analysis and distribution; grain size; inclwsions:
macrostructwre; porosity; segregation; surface anomalies
Auxiliary categories
Image generation
Signal image analysis
dimensional variations; dynamic performance; anomaly characterization ana definition; anomaly
distribution: anomaly propagation; magnetic field configuratiOns
data selection, processing and display; anomaly mapping, correlation and identification; image
enhancement; separation of mUltiple variables; signature analysis
Table L The first six categories involve basic physical processes that require transfer of matter and/or energy with
respect to the object being inspected, Two auxiliary categories describe processes that provide for transfer and accumulation of information, and evaluation of the raw signals
and images common to nondestructive testing methods.
Principles
. Each method can be completely characterized in terms
of five principal factors:
1. energy source or medium used to probe object (such
as X-ravs, ultrasonic waves or thermal radiation);
2. nature 'of the signals, image and/or signature resulting from interaction with the object [attenuation of
X-rays or reflection of ultrasound, for example);
3, means of detecting or sensing resultant signals (photoemulsion, piezoelectric crystal or inductance coil);
4. method of indicating and/or recording signals (meter
deflection. oscilloscope trace or radiograph); and
5. basis for interpreting the results (direct or indirect
indication. qualitative or quantitative. and pertinent
dependencies).
The objective of each method is to provide information
about the follO\ving material parameters:
1. discontinuities and separations (cracks, voids, inclusions, delaminations etc.):
2. structure or malstructure (crystalline structure, grain
size, segregation, misalignment etc.),
3. dimensions and metrology (thickness, diameter, gap
size, discontinuity size etc.),
4. physical and mechanical properties (reflectivity, conductivity, elastic modulus, sonic velocity etc.),
.5. composition and chemical analysis (alloy identiflcation.Jmpurities, elemental distributions etc.):
6. stress and dynamic response (residual stress, crack
growth, wear, vibration etc.), and
I. signature analysis (image content, frequency spectrum, field configuration etc.).
Terms used in this block are further defined in Table 2
'With respect to specific objectives and specific attributes to
be measured, detected and defined,
The limitations of a method include conditions required
by that method: conditions to be met for technique application (access. physical contact preparation etc.) and
requirements to adapt the probe or probe medium to the
object examined, Other factors limit the detection and/or
characterization of discontinuities, properties and other
attributes and limit interpretation of signals and/or images
generated.
INTRODUCTION TO NONDESTRUCTIVE TESTING I 17
TABLE 2. Objectives of nondestructive testing methods
Attributes Measured or Detected
Objectives
Discontinuites and separations
Surfaceanomalies
roughness; scratches; gouges; crazing; pitting; Inclusions and Imbedded foreign material
Surface connected anomalies cracks; porosity; pinholes; laps; seams; folds; Inclusions
Internal anomalies
cracks; separations; hot tears; cold shuts; shrinkage; voids; lack of fusion; pores; cavities;
delarrunations: disbands; poor bonds; Inclusions; segregations
Structure
Microstructure
Matrix structure
Small structural anomanes
Gross structural anomalies
molecular structure; crystalline structure and/or strain; lattice structure; strain; dislocation; vacancy;
deformation
grain structure, size, orientation and phase; sinter and porosity; impregnation; filler and/or
reinforcement distribution; anisotropy; heterogeneity; segregation
leaks flack of seal or through-holes); poor fit; poor contact; loose parts; loose particles; foreign objects
assembly errors; misalignment; poor spacing or ordering; deformation; malformation; missing parts
Dimensions and metrology
Displacement: position
Dimensional variations
Thickness; density
linear measurement; separation; gap size; discontinuity size, depth, location and orientation
unevenness; nonuniformlty; eccentricity; shape and contour; sizeand mass variations
film, coating, layer, plating, wall and sheet thickness; density or thickness variations
Physical and mechanical properties
Electrical properties
Magnetic properties
Thermal properties
Mechanical properties
Surface properties
resistivity; conductivity; dielectric constant and dissipation factor
polarization; permeability; ferromagnetism; cohesive force
conductivity; thermal time constant and ther';10electrlc potential
compressive, shear and tensile strength (and modull); Poissons ratio; sonic velocity; hardness; temper
and embntnement
color; reflectiVity; refraction index; emissivity
Chemical composition and analysis
Elemental analysis
Impurity concentrations
Metallurgical content
Physiochemical state
detection; Identification, distribution and/or profile
contamination; depletion; doping and diffusants
variation; alloy identification, verification and sorting
moisture content; degree of cure; ion concentrations and corrosion; reaction products
Stress and dynamic response
Stress; strain; fatigue
Mechanical damage
Chemical damage
Other damage
Dynamic performance
heat-treatment, annealing and cold-work effects; residual stress and strain; fatigue damage and life
(reSiCfual)
wear; spalling; erosion; friction effect>
corrosion; stress corrosion; phase transformation
radiation damage and high frequency voltage breakdown
crack initiation and propagation; plastic deformation; creep; excessive motion; vibration; damping;
timing of events; any anomalous behavior
Signature analysis
Electromagnetic field
Thermal field
Acoustic signature
Radioactive signature
Signal or image analysis
potential; strength; field distribution and pattern
Isotherms; heat contours; temperatures; heat flow; temperature distribution; heat leaks; hot spots
noise; vibration characteristics; frequency amplitude; harmonic spectrum and/or analySIS; sonic and/or
ultrasonic emissions
distribution and diffusion of isotopes and tracers
image enhancement and quantization; pattern recognition; densitometry; signal classification,
separation and correlation; discontinuity identification, definition (SiZe and shape) and distribution
analysis; discontinuity mapping and display
18 / NONDESTRUCTIVE TESTING OVERVIEW
PART 4
UNITS OF MEASURE FOR
NONDESTRUCTIVE TESTING
Origin and Use of the SI System
$1 Units for Radiography
In 1960 the General Conference On Weights and Measures devised the International System of Units. Systeme
Internationale (SI) was designed so that a single set of inter"
related measurement units could be used by all branches of
science, engineering and the general public. Without SI,
this Nondestructioe Testing Handbook volume could have
contained a confusing mix of Imperial units, obsolete centimeter-gram-second (cgs) metric system units and the units
preferred by certain localities or scientific specialties.
SI is the modem version of the metric system and ends
the division between metric units used by scientists and
metric units used by engineers. Scientists have given up
their units based on centimeter and gram and engineers
made a fundamental change in abandoning the kilogramforce in favor of the newton. Electrical engineers have
retained their amperes, volts and ohms but changed all units
related to magnetism. The main effect of SI has been the
reduction of conversion factors between units to one (1) ~
in other words, to eliminate them entirely.
Table :3 lists seven base units. Tabl~ 4 lists all of the
derived units with special names. In SI, the unit of time is
the second (s) but hour (h) is recognized for use with S1.
For more information, the reader is referred to the information available through national standards organizations
and specialized information compiled by technical societies
(see ASTM E 380, Standard Practice for Use of the International System of Units, for example),"
The original discoveries of radioactivity helped establish
units of measurement based on observation rather than precise physical phenomena. Later scientists who worked with
radioactive substances (or who managed to manufacture
radioactive beams) again made circumstantial observations
that were then used for measurement purposes. This was
acceptable at the time hut with our broader understanding
of physics and the present tendency to use one unit for one
concept, many of the original units have been modified (see
Tables 4 and 5).
TABLE 3. Base SI units
Quantity
Unit
Symbol
m
Length
Mass
meter
kilogram
kg
Time
second
s
Electric current
Temperature"
Amount or substance
Luminous intensity
ampere
kelVin
A
mole
mol
candela
cd
K
• KELVIN CAN BE EXPRESSED IN DI;GREES CELSIUS ("C '" K - 273.15).
TABLE 4. Derived SI units with special names
Relation
to Other
Quantity
Frequency (periodic)
Force
Pressure (stress)
Energy (work)
Power
Electric charge
Electric current
Electric potential o
Capacitance
Electric resistance
Conductance
Magnetic flux
Magnetic flux density
Inductance
luminous flux
Illuminance
Plane angle
RadioactiVity
Radiation absorbed dose
Radiation dose equivalent
Solid angle
Units
Symbol
51 Unitsa
hertz
newton
pascal
JOUle
watt
coulomb
ampere
volt
farad
ohm
siemens
weber
Hz
N
Pa
kg·m·s- 2
J
W
C
A
V
F
n
S
Wb
testa
T
henry
lumen
lux
radian
becquerel
H
1m
Ix
rad
Bq
gray
sievert
Gy
Sv
steradian
sr
a. NUMBER ONE EXPRESSES DIMENSIONLESS RELATIONSHIP.
b. elECTROMOTIVE FORCE .
1,5- 1
N,m-2
N·m
J·r l
As
V·Q-I
W·N 1
(V- 1
V·A- 1
AV- 1
V·s
Wbm-2
Wb·A- 1
cosr
Imm- 2
)
Is- J
Jkg-J
Jkg- I
1
INTRODUCTION TO NONDESTRUCTIVE TESTING I 19
TABLE 5. Examples of conversions to 51 units
Quantity
Measurement in Non-SI unit
Multiply by
To Get Measurement in SI Unit
meter per second per second (m·s~21)
Acceleration
ft·s-2 (0:: graVity)
- 9.8
square millimeter (mm 2)
Area
square inch [in. 2)
645
nanometer (nm)
Distance
angstrom (A)
0.1
millimeter [rnrn]
inch (in.)
25.4
kilojoule (kJ)
Energy
1.055
British thermal unIt (BTU)
4.19
joule (J)
calorie (cal)
0.293
watt (W)
British thermal unit per hour (BTU·h~l)
kilojoule per kilogram-kelvin (kJ/kg-K)
Specific heat
4.19
British thermal unit per pound
per degree Fahrenheit (BTU·lbm-l.aF-I)
Force
newton (N)
pound force (lbr)
4.45
joule (J)
1.36
Force (torque, couple)
foot-pound (ft-Ibd
6.89
kilopascal (kPa)
Force or pressure
pound per square inch (lbf·in.- 2)
1/60
hertz (Hz)
Frequency (cycle)
cycle per minute
1·s-1
1/60
Frequency (revolution)
revolution per minute (rpm)
lux (Ix)
Illuminance
10.76
rootcancne {ftc or rc)
candela per square meter (cd·m~2)
Luminance
candela per square foot (Cd·f'l2)
10.76
candela per square meter (cd·m~2)
candela per square inch (in..f'l2)
1,550
candela per square meter (cd·m~2)
footlarnbert
3.426
candela per square meter {cd·m-2j
3.183 ('" 1O.OOOl1t)
lambert
I x 10~
weber (Wb)
Magnetic flux
maxwell. or line
Magnetic flux density
testa (T)
gauss, or maxwell per square centimeter 1 X 10-4
41t X 10-3
Magnetic field intensity
ampere per square meter (A·m2)
oersted (Oe)
Radioactivity
curie ((i)
37
gigabecquerel (GBq)
IoniZing radiation exposure roentgen [R)
millicoulomb per kilogram (mC-kg- l )
0.258
rMiation absorbed dose (rad)
0.01
gray {Gyj
Dose absorbed by matter
Dose absorbed by human raotanon equivalent man (rem)
slevert (Sv)
0.01
Mass
0454
kilogram (kg)
pound (Ibm)
degree celsius (OCi
Temperature (difference)
degree Fahrenheit (OF)
0.556
(OF - 32)/1.8
degree celsius (OCi
Temperature (scale)
degree Fahrenheit [OF)
(OF - 32)/1 .8) + 273.15 kelvin (K)
Velocity
inch per second (in. 'S-I)
meter per second [m·s- I )
0.0254
meter per second (m·s- I )
mile per hour (mi·h- I )
0447
Single Unit Comparisons
. The original curie was Simply the radiation of one gram
of radium. Eventually all equivalent radiation from any
source was measured with this same unit. The original
roentgen was the quantity of radiation that would ionize one
cubic centimeter of air to one electrostatic unit of electricity
of either sign. It is now known that a curie is equivalent to
37 x 109 disintegrations per second and a roentgen is equivalent to 258 microcoulombs per kilogram of air. This corresponds to 1.61 X 1015 ion pairs per kifogram of air which has
absorbed 8.8 millijoules (rnJ) or 0.88 rads.
The roentgen was an intensity unit but was not representative of the dose absorbed bv material in the radiation field.
The radiation absorbed dose. rad. was first created to measure this value and was based on ergs, an energy unit from
the centimeter-gram-second (cgs) system.
In 51. radiation units have been given established physical foundations and new names where necessarv,
The unit for radioactivitv (formerlv curie)' is the beequerel (Bq) which is one disi;1tegration'per second. Because
billions of disintegrations are required in a useful source,
the multiplier prefix giga (l09) is nearly always necessary
and the unit is normally used as gigabecquerel (CBq).
The unit for radiation dose (formerly the rad) is the gray
(Cy) in the 51 system. The gray is useful because it applies
to doses which are absorbed by matter at a particular location. It is expressed in energy units per mass of matter or
joules per kilogram (J .kg- i ) . The mass is normally that of the
absorbing body.
The 51 unit for the dose absorbed bv the human bodv
(formerly rem for roentgenequival~nt man) is similarto th~
gray but includes quality factors that depend on the type of
radiation. This absorbed dose has been given the name sievert (Sv) but its dimensions are the same as the gray (J-kg-1) .
Combination Units
Roentgens could he measured with an ionization chamber whd1, when placed one meter from the radiation
source, provided a good deal of necessary information
(roentgen per hour per curie at one meter, for example).
20 / NONDESTRUCTIVE TESTING OVERVIEW
The numbers, though, had limited physical meaning and
could not be used for different applications such as highvoltage X-ray machines.
The roentgen per hour (R·h~I) was used to designate the
exposure to an Ionizing radiation of the stated value. The SI
unit used for this is the sievert (Sv), which is 100 times as
large as the rem it replaces.
Because the received radiation from 1 R.h-I was considered about equal to 1 rem, the relationship is now approximated as 1 R·h- I '" om Gy.h-I. This is better expressed as
1 R·h-I = 10 mGy.h- I with higher levels of radiation in the
range of one gray.
A previously popular unit, roentgen per hour at one
meter per curie, is expressed in 51 units as millisievert per
hour at one meter per gigabecquereI, such that:
In this relationship, roentgens converts to rnillisieverts on a
1 to 10 basis.
.
Exposure charts may use curie-minutes at a source-tofilm distance in inches squared, This was written min/in.2.
Exposure charts made in SI use gigabecquerel-minutes for a
source-to-film distance in centimeters squared, where 1 Cimin-in.r? '" 50 GBq~min.cm~2. Table 5 lists some of these
new combination units.
Fundamental 51 Units Used for
Leak testing
Pressure
The pascal (Pa), equal to one newton per square meter
(1 N-m-2 ) , is used to measure a force per unit area. It is used
in place of units of pounds force per square inch (lbf·in,·Z),
atmospheres, millimeters of mercury (rnm Hg), torr, bar,
inches of mercury (in. Hg), inches of water and other prior
units. It is mostly used with multipliers (prefixes) such as
mega-, kilo-, milli- and mlcro-. No-connotations shall ever
be attached to SI units. 51 units of pressure are normally
absolute pressures, However, the text indicates whether
gage, absolute or differential pressure was meant. Negative
pressures might be used in heating duct technology and in
vacuum boxes used for bubble testing, but in vacuums, used
in tracer leak testing, absolute pressures are used,
Volume
The cubic meter (m» is the only volume measurement
unit in 51. It takes the place of cubic feet, cubic inches, gallons, pints, barrels and more, Sometimes, liters (1O~m3) or
milliliters (10-6 m3 ) appear in the text as exceptions for fluid
volumes.
Multipliers
Units that are either very large or very small are used
with 51 multipliers that are prefixes, mostly of 103 intervals.
The multiplier becomes a property of the 51 unit, e,g., a
centimeter (em) is 1/100 of a meter, and the volume unit of
a cubic centimeter (cm3) is (11100)3 or 10-6 cubic meter
(m"), Note: A cm3 is not equal to 11100 m3 . Also, in equations, use of units such as centimeters (em), decimeters
(dm) or centiliters (cL) should be avoided since such units
disturb the convenient 103 or 1O~> intervals which make
equations easy to manipulate,
Scientific Notation. Leakage rates covering many orders
of magnitude have been expressed in powers often, e.g" 6 x
10-5, I X 10-9 etc.
Derived 51 Units for Leak Testing
The follOWing derived 51 units were adopted for leak
testing.
Gas quantity. Pascal cubic meter (Pa.m3), The quantity
of gas stored in a container Orwhich has passed through a
leak is described by the derived 51 unit of pascal cubic
meter, the product of pressure and volume. To be strict, the
temperature should be specified for the gas volume or leakage measurement to define the gas quantity (sometimes
loosely described as the mass of gas) more precisely. Often,
gas quantity is defined for standard temperature and pressure, typically the standard atmospheric pressure, 101 kPa,
and a temperature of 20 °C(293 K). Temperature corrections are usually required if temperature varies significantly
during leak testing. However, small changes in temperature
may sometimes be insignificant compared with many orders
of magnitude of change in gas pressure or leakage quantity.
Gas leakage rate. Pascal cubic meter per second
(Pa.m3.s~1). The leakage rate is defined as the quantity
(mass) of gas leaking in one second. The unit in prior use
was the standard cubic centimeter per second (std cm3.s~I).
Use of the word standard in units such as std cm3·s- I
requires that gas leakage rate be converted to standard ternperature and pressure conditions (293 K and 1Ol.325 kPa),
often even during the process of collecting data during leak.
age rate tests, Expressing leakage rates in the 51 units of
Pa·m3·s~1 provides a leakage rate valid at any pressure. Leakage rates given in 51 units of Pa,m3·s- 1 can be converted to
units of std cm3·s~1 at any time by simply multiplying the 51
leakage rate by 10 or (more precisely) by 9.87. For conversions, 1 Pa·m',s-l ¢ 10 std cm3·s- l .
Gas permeation rate. Pascal cubic meter per second per
square meter per meter (Pa.m3·s-I )/(m 2.m- 1 ). Permeation is
INTRODUCTION TO NONDESTRUCTIVE TESTING I 21
the leakage of gas through a (typically solid) substance that
is not impervious to gas Row. The permeation rate is larger
with an increased exposed area, a higher pressure differential across the substance (membrane,gasket etc.), and is
smaller with an increasing thickness of permeable substance. In vacuum testing, the pressure differential is usually considered to be one atmosphere (101 kPa). One
sometimes finds units of permeation rate where the gas
quantity is expressed in units of mass and where the differential pressure is- expressed in various units. Equation 4
expresses an equivalence for conversion of measurements:
(Eq.4)
Rounding. Many tables and graphs were obtained from
researchers and scientists who did their work in the English
system. In the conversion, some numbers have been
rounded drastically but some were left as irrational numbers
in the metric version, especially where quotes were made to
specific entries.
a hypothetical wire one meter (1 m) long and one square
millimeter (I mm'') in cross section. This comparison is
immaterial because no actual wire is involved. Hence, for
conformance to S1, this unit could be changed to mlQ·m 2,
which reduces to l/Q·m. Because l/Q is also conductivity in
siemens (S), material conductivity could be expressed in
S/m:
1m
(Eq.6)
Resistivity has sometimes been given in Q·cm, where
1 Q·cm '" 0.01 Q·m.
51 Units for Other Nondestructive
Testing Methods
Optical Units
51 Units for Electrical and Magnetic
Testing
Magnetism Units
The SI unit for magnetic flux is the weber (Wb), which
replaces the maxwell: 1 wb = 108 maxwells. The density of
magnetic flux (i.e., how much flux passes perpendicularly
through a unit of area) is measured in tesla (T); 1 T =
1 Wb·m- 2 . The older unit is the maxwell per square centimeter, or gauss (G); 10 4 G = 1 T. The gauss meter used in
nondestructive testing is now called the tesla meter.
Magnetic field strength, formerly expressed in oersted
(Oe, a nonexisting physical agent enabling analysis of complex magnetic field problems), is ex-pressed in SI by ampere
per meter (A.m~I):
lA'm- 1
_
4n:
x
_ L2.57
10-:' Oe
X
1O~2
(Eq.5)
Oe
Vision requires a source of illumination. The light source
is the candela (cd), defined as the luminous intensity in a
given direction of a source that emits monochromatic radiation of 540 x 10 12 hertz (Hz) at a radiant intensity of
1/683 watt per steradian (W·sr~I).
'
The luminous flux in a steradian (sr) is measured in
lumens (Irn). The measurement in lumens is the product of
candela and steradian (11m", Lcd-sr),
A light [lux of one lumen (11m) striking one square
meter (1 m 2) on the surface of the sphere around the source
illuminates it with one lux (1 lx), the unit of illuminance. If
the source itself is scaled to one square meter (1 m2 ) and
emits one candela (1 ed), the luminance (formerlv called
brightness) of the source is 1 cd·m-2 .
'
Some terms have been replaced. Illumination is now
illuminance; brightness is luminance; transmission factor ,is
transmittance. Meter-candle is now lux and nit is candela
per square meter (cd-rrr<).
Old units are to be converted (see Table 5). Footcandle (ftc) and phot now convert to lux (Ix), Stilb (sb), footlambert and lambert convert to candela per sCJ.uare meter
(cd.m- 2 ) . Nanometer (nm) replaces angstrom (A) for wavelength.
Conductivity and Resistivity Units
Decibel
This text covers material conductivitv measurements and
favors the term mlQ.mm 2, comparing material properties to
The decibel is not an $1 unit. It is an indication of the
ratio between two conditions of the same dimension (such
22 I NONDESTRUCTIVE TESTING OVERVIEW
as voltages or powers) and is extensively used in electronics.
The fundamental decibel is:
(Eq.7)
Where:
P
Po
measured power; and
reference power.
The power is, in a sense, a square function of voltage and
the decibel could also be written as:
N dB
=
10log 1o (
~
J
(Eq.8)
This in tum translates to:
-
201og 1o -
v
Vo
(Eg.9)
and ex-plains why there are often two definitions given for
the decibel (sometimes written dBV for voltage decibels),
No connotations are attached to 51 units and conditions are
expressed parenthetically, such as dB(V).
Prefixes for 51 Units
Very large or very small units are expressed by using the
51 multipliers, prefixes usually of 10 3 intervals (Table 6).
The multiplier becomes a property of the 51 unit For example, a millimeter (rnrn) is 0.001 meter (rn). The volume unit
TABLE 6. SI mUltipliers
Prefix
Symbol
Multiplier
yarra
Y
1024
zetta
Z
E
1021
10 18
lOIS
10 12
109
106
103
102
10
exa
peta
P
tera
giga
mega
T
kilo
hecto"
G
M
k
h
deka (or deea) *
deei*
ca
d
centi"
c
10- 2
milli
m
micro
j.J
10-3
I 0- 6
10-1
nanD
n
10~
pica
p
10-12
femto
flO-IS
atto
a
zepto
Z
yoctc
Y
J 0- 18
I 0- 2 J
I 0- 24
• AVoiD THESE PREFIXES (EXCEPT IN <1m 3 A/IIO cm 3 ) FORSelENeE AND
ENGINEERING.
cubic centimeter (em") is (0.01)3 or 10- 6 m 3. Units such as
the centimeter, decimeter, dekameter (or decameter) and
hectometer are avoided in scientific and technical uses of 51
because of their variance from the 103 interval. However,
dm 3 and cm-' are in use specifically because they represent a
103 variance.
In 51, the distinction between upper and lower case letters is meaningful and should be observed. For example, the
meanings of the prefix m (rnilh-) and the prefix M (mega-)
differ by nine orders of magnitude.
INTRODUCTION TO NONDESTRUCTIVE TESTING I 23
REFERENCES
L Betz, C. 'The Nondestructive Testing Engineer Today's Career Opportunity." Nondestructive Testing.
Vol. 18, No. L Columbus, OR: American Society for
Nondestructive Testing (January-February 1960):
P 15-26. ,
2. Wenk, SA and R.C. McMaster. Choosing NDT: Applications, Costs and Benefits of Nondestructive Testing
in Your Quality Assurance Program. Columbus, OR:
American Society for Nondestructive Testing (1987).
3.
4.
McMaster, KC. and SA Wenk. A Basic Guide for
Management's Choice of Nondestructive Tests.
Special Technical Publication No. 112. Philadelphia, PA: American Society for Testing and Materials (1951).
Standard Practicefor Use of the International System of Units (S1) (The Modernized Metric System).
ASTM E 380-93. Philadelphia, PA: American Society for Testing and Materials (1993).
24 / NONDESTRUCTIVE TESTING OVERVIEW
BIBLIOGRAPHY
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
ASM Handbook, ninth edition: VoL 17, Nondestructive Evaluation and Quality Control. Materials
Park, OR: ASM International (1989).
Annual Book ofASTM Standards: Section 3, Metals
Test Methods and Analytical Procedures. Vol.03.03,
Nondestructive Testing. West Conshohocken, PA:
American Society for Testing and Materials [revised
annually].
Bray, D.E. and D. McBride, ed. Nondestructive
Testing Techniques. New York. NY: John Wiley &
Sons (1992).
Bray, D.E. and R.K. Stanley Nondestructive Evaluation: A Tool in Design, Manufacturing, and Service. New York, NY: McGraw-Hill (1989).
Cartz, L. Nondestructive Testing: Radiography,
Ultrasonics, Liquid Penetrant, Magnetic Particle,
Eddy Current. Materials Park, OR: ASM International (1995).
Halmshaw, R. Introduction to the Non-Destructive
Testing of Welded joints. Cambridge, United Kingdom: Abington Publishing (1988).
Halmshaw, R. Non-Destructive Testing, second edition. London, United Kingdom: Edward Arnold
(1991).
Hull, B. and V John. Non-Destructive Testing. Basingstoke, United Kingdom: Macmillan (1988).
McMaster, RC., ed. Nondestructive Testing Handbook, first edition Columbus, OH: American Society for Nondestructive Testing (1959).
Mathematics and Formulae in NDT, second edition,
revised. Northhampton, United Kingdom: British
Institute of Non-Destructive Testing (1993).
Nondestructive Testing Handbook, second edition:
Vol. I, Leak Testing. Columbus, OR: American
Society for Nondestructive Testing (1982).
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
Nondestructive Testing Handbook, second edition:
Vol. 2, Liquid Penetrant Tests. Columbus, OH:
American Society for Nondestructive Testing (1982).
Nondestructive Testing Handbook, second edition:
Vol. 3, Radiography and Radiation Testing. Columbus, OR: American Society for Nondestructive
.
Testing (1985).
Nondestructive Testing Handbook, second edition:
Vol. 4, Electromagnetic Testing. Columbus, OH:
American Society for Nondestructive Testing (1980).
Nondestructive Testing Handbook, second edition:
Vol. 5, Acoustic Emission. Testing. Columbus, OR:
American Society for Nondestructive Testing (1987).
Nondestructioe Testing Handbook, second edition:
Vol. 6, Magnetic Particle Testing. Columbus, OH:
American Society for Nondestructive Testing (1989).
Nondestructive Testing Handbook, second edition:
VoL 7, Ultrasonic Testing. Columbus, OR: American Society for Nondestructive Testing (1991).
Nondestructive Testing Handbook, second edition:
VoL 8, Visual and Optical Testing. Columbus, OH:
American Society for Nondestructive Testing (1993).
Nondestructioe Testing Handbook, second edition:
Vol. 9, Special Nondestructive Testing Methods.
Columbus, OR: American Society for Nondestructive Testing (1995).
Nondestructive Testing Methods. T033B-I·I
(NAVAIR 01-IA-16) TM43-0103. Washington, DC:
Department of Defense United States Air Force
(June 1984).
Wenk, SA and R.c. McMaster. Choosing NDT:
Applications, Costs and Benefits of Nondestructive
Testing in Your Quality Assurance Program.
Columbus, OH: American Society for Nondestructive Testing (1987).
SECTION
2
LEAK TESTING
Charles N. Sherlock, Willis, Texas
A PORTION OF PART :3 IS ADAPTED FROM THE ASTM BOOK OF STANDARDS; E 427. STANDARD FRACTICE FOR TESTING FOR LEAKS USING THE HALOGEN LEAK
DETECTOR IALKALI·LON DIODEI, e AMERICAN SOCIETY FOR TESTING AND MATERIALS. REPRINTED WITH PERMISSION
o
...
"'
.....'" ......
NONDESTRUCTIVE TESTING
GLOSSARY
.
-
.
..
- .
516 I NONDESTRUCTIVE TESTING OVERVIEW
Introduction
Most of the definitions in this glossary are adapted from
the text of Volumes 1 through 9 of the second edition Nondestructive Testing Handbookr" The definitions in this
glossary have been modified to satisfy peer review and editorial style. For this reason, references given in this glossary
should be considered not attributions but rather acknowledgments and suggestions for further reading.
The definitions in this Nondestructive Testing Handbook
volume should not be referenced for inspections performed
according to standards or specifications or in fulfillment of
contracts. Standards writing bodies take great pains to
ensure that their documents are definitive in wording and
technical accuracy. People working to Written contracts or
procedures should consult definitions referenced in real
standards when appropriate.
This glossary is provided for instructional purposes. No
other use is intended.
A
A-scan display: A display in which the received signal
amplitude is shown as a vertical excursion from the 110r\
izontal sweep time trace. The horizontal distance
between any two signals represents the material distance between the two conditions causing the signals.lO
In a linear system, the vertical excursion is proportional
to the amplitude of the signal.'
absolute coil: A coil of electricallv conductive wire that
responds to the electromagnetic properties of that region
of the test object that is within the magnetic field of the
coil, without comparison to the response of a second coil
)
at a differ.ent loca.tion on the same or simil.ar material."
[absolute measurement: Measurement made with an
i,
absolute coil.4
absolute pressure: Pressure above absolute zero value, or
pressure above that of empty space. Equal to sum of
local atmospheric pressure and gage atmosphere.'
absolute temperature: Temperature measured from absoI
lute zero temperature, expressed in Kelvin (K) in SV
(absorbed dose: The amount of energy imparted to matter
I
by an ionizingparticle per unit mass of irradiated material at the place of interest. Absorbed dose is ex'Pressed
1
in Gray (Gy) or rads.i)
absorption coefficient, linear: The fractional decrease in
transmitted intensity per unit of absorber thickness. It
is usually designated by the symbol ~ and ex'Pressed in
units of cm- l .7.l2
acceptable quality level (AQL): The maximum percent
defective (or the maximum number of units with
rejectable anomalies per hundred units) that, for the
purposes of sampling tests, can be considered satisfactory as a process average,"
I
acceptance criteria: The standard against which test
results are to be compared for purposes of establishing
the functional acceptability of a part or system being
examined.
acceptance level: A test level above or below which test
objects are acceptable in contrast to rejection level. 4.13
acceptance standard: A specimen similar to the test
object containing natural or artificial discontinuities
that are well defined and similar in size or extent to the
maximum acceptable in the product. See reference
standard and standard. 4.6.,
.
accommodation: Of the eye, adjustment of the lens' focusing power by changing the thickness and curvature of
the lens by the action of tiny muscles attached to the
lens. 8
accumulation test technique: Detecting the total amount
of leakage by enclosing the component under test
within a hood, bag, box, shroud or container. For pressure testing, any gas leaking from the component accumulates in the space (volume) between the component
and the enclosure. For vacuum testing, any gas leaking
into the component accumulates in the leak detector
sampling the evacuated component. Accumulation of
tracer gas in a measured time period provides a measure of the leakage rate.'
accuracy: The degree of conformity of a measurement to a
standard or true value.'
acoustic emission: The transient elastic waves resulting
from local internal micro displacements in a material.
The term also describes the technical discipline and
measurement technique relating to this phenomenon.f
acoustic emission activity: The number of bursts (or'
events, if the appropriate conditions are fulfilled)
detected during an acoustic emission test."
acoustic emission count: The number of times the signal
amplitude exceeds the preset reference threshold,"
acoustic emission event: A microstructural displacement
that produces elastic waves in a material under load or
stress. 5
acoustic emission rate: The number of times the amplitude has exceeded the threshold in a specified unit of
time. 5
acoustic emission testing (AE): Nondestructive test
method that uses acoustic emission.
acoustic impedance: A material property defined as the
product of sound velocity and density of the material. 1.12
acoustic microscopy: High resolution, high frequency ultrasonic techniques used to produce images of features
beneath the surface of a test object.'
acuity: See neural acuity, vision acuity.
adaptive thresholding: Threshold value varying with inconstant background gray level."
adhesive wear: See wear, adhesive.
NONDESTRUCTIVE TESTING GLOSSARY I 5
AE: Acoustic emission testing.
age hardening: A process of aging that increases hardness
and strength, but that ordinarily decreases ductility.
Also known as precipitation hardening. 3
agency: The organization selected by an authority to perform nondestructive testing, as required by a specification or purchase order. 2
air dried: Drying of any item such as a core or mold without application of heat. 3
air injection machine: A die casting machine in which air
pressure acts directly on the surface of molten metal in a
closed pot (gooseneck) and forces the metal into a die. 3
air flow: In leak testing, the flow of air from the probe inlet
to the sensitive element of the halogen leak detector that
carries the tracer gas from the leak to the sensing diode. 1
algorithm: A prescribed set of well defined rules or processes for the solution of a mathematical problem in a
finite number of steps.v'"
alkali ion diode: A sensor for halogen gases. In this device,
positive ions (cations) of an alkali metal are produced on
the heated surfaces (usually platinum) of the diode. One
electrode is ata negative potential and attracts cations
that are released when a halogen gas passes between the
sensor electrodes. Provides an output current to operate
the indicator on the halogen leak detector. 1
alpha ferrite: The form of pure iron that has a body centered cubic structure stable below 910°C (1,670 OF).
Also called alpha iron. S
alpha particle: A positively charged particle emitted by
certain radioactive materials. It is made up of two neutrons and two protons; hence it is identical with the
nucleus of a helium atom.l!
alternating current: An electrical current that reverses its
direction of flow at regular intervals.?
alternating current field: The varying magnetic field produced around a conductor by an alternating current
flowing in the conductorf
alternating current magnetization: Magnetization by a
magnetic field tl:at is generated when alternating current is flowing. 6 ,1;'
ambient light: Light in the environment as opposed to illumination provided by a visual testing system. 8
ambient or atmospheric temperature: Temperature of
surrounding atmosphere. Also called dry bulb temperature.
ampere: A unit of electric current. Abbreviated A or amp.6
ampere per meter: The SI base unit for magnetic field
strength in air at the center of a single-tum Circular coil
having a diameter of 1 m, through- which a current of
1 A is flOwing. Abbreviated A-m- r or Aim. 1 A·m~l '" 1.3
X 10-2 Oe (see oersted). 6,15
ampere turns: The product of the number of turns of a coil
..and the current in amperes flowing through the coi1.6,16
amplitude distortion: See harmonic distortion.
amplitude response: That property of a test
whereby the amplitude of the detected signal is me"
sured without regard to phase, See also harmonic
lyzer and phase analysis,4,13
.
amplitude, echo: The vertical height of a received signal
an A-scan, measured from base to peak for video or
to peak for radio frequency presentation."
analog-to-digital converter: A circuit whose input
information in analog form and. whose output -is the
. ;;:.
!lame information in digital form. 4,14
angle: Seefj~ld angle.
angle beam: An ultrasound beam traveling at an
a.ng.Ie Into.a m.e~um. Theangle of incidence or refrac.·.'l.•. . . .
tion after entry IS measured from the normal to th]
entrv surface. i,12
angle of incidence: The included angle between the beam
axiS. of .th~ inci?e~t. w.ave !nd the normal to the surfac"]..
at the pomt of incidence. 1.10
... 1
angle of reflection: The included angle between the beam
b
axis.of th.e. re.f. le. c.te.d w.. a.ve.and..-. t he. no:mal to the reflec .·..·. ·1
. .•
ing surface at the point of reflection. 1.10
angle of refraction: The angle between the beam axis of a1
. refracted wave and the normal to the refracting inte~,:"
i,10
face.
angle testing: A method of ultrasonic testing in whic. . •.•
transmission of ultrasound is at. an acute angle to the
entry surface. Usually called angle beam testing. 7,lO . ]
angle transducer: A transducer that transmits or receiVEJ
ultrasonic energy at an acute angle to the surface. This
m
. .. ay be do.ne to a.chieve. special-.effects such ~s settin..a..'•.
up shear or surface waves by mode conversion at a •
interface. 7J O
angstrom: A unit of distance abbreviated A. and used to
. express wavelengths of electromagnetic radiation. The E
unit nanometer (rim) is now preferred; 1 nm ;; 10 A.2.8
anisotropy: The characteristic of exhibiting different values
of a property (velocity, for example) in different direc
tions in the material,"
annealing: Process of heating and cooling a material,
ally to reduce residual stresses or to make it softer. 2.3..8
annular coil clearance: The mean radial distance betwee
the inner diameter of an encircling coil assembly
test object surface in electromagnetic examination. See
fill factor. 4 ,13
anode: (1) In radiography, the positive electrode of an
tron tube. (2) Negatively charged terminal, which
corrode electrochemically during production of ani
electric current. Compare cathode. 8
I
anomaly: A variation from normal material or prodUCt$
quality.4
antinode: A point in a standing wave where certain
teristics of the wave field have maximum amplitude.
AOQ: Average outgOing quality.
AOQL: Average outgOing quality limit.
'1'
l.
·
h
.
518 / NONDESTRUCTIVE TESTING OVERVIEW
AQL: See acceptable quality level.
arbor: A bar or mandrel on which a core is built."
arc: A luminous high temperature discharge produced
when an electric current flows across a gaseous gap.6.15
arc strikes: Localized bum damage to an object from the arc
caused by breaking an energized electric circuit. Also
called arc burns. 6.16
arc welding: See electric arc welding.
arcing: Current flow through a gap, often accompanied by
intense heat and light. G.1'
Argand diagram: A graphical representation of a vector
used in complex notation. 4. l4
array: (1) A group of transducers used for source location.P
(2) An arrangement of sensors used for image building.
(3) A group of transducers arranged for beam shaping
or beam control.
'/ array tra~sducer,:"A .tra,~s:Iuc,'e,',r, made, up o,fseveral pie~o\
electric elements individuallv connected so that the Slg\
nals thev transmit or receiv~ mav be treated separatelv
or combined as desired.'
"] articulated pole pieces: On a magnetizing yoke, indepen\
dently adjustable magnetic elements enabling the magnetization of irregular test object profiles."
')artifac~: In n,'on destructive tes,ting,a,n,' indi.cat~ono that may
\
be mterpreted erroneouslv as a discontinuitv.f
artificial discontinuity stand~rd: See acceptance standard.
lartificial discontinuity: Refe~ence point,. such as a hole,
I
groove or notch, that are introduced into a reference
standard to provide accurately reproducible sensitivity
)
levels for nondestructive test equipment. ·U3 A manufactured material anomaly. See acceptance standard
and reference standard. 6
artificial flaw standard: See acceptance standard.
)artificial SOurce: In acoustic emission, a point where elastic
\
waves are created to simul.ate an acoustic emission even!.
The term also defines devices used to create the waves."
ASNT: American Societv for Nondestructive Testing.
¥'-SNT Recommended Practice No. SNT.TC-IA: A set of
guidelines for employers to establish and conduct a
nondestructive testing personnel qualification and certification program. SNT-TC-1A was first issued in 1968
by the Society for Nondestructive Testing (Sr\T, now
ASNT) and has been revised every few years sinoe."
atmosphere: See standard atmospheric conditions.
~tmospheric pressure: Ambient pressure caused by the
\
weight of the earth's atmosphere. Because the weight of
the earth's overlying atmosphere decreases with increase
in altitude, barometric pressure decreases at higher elevations above sea level. Also called barometric pressure.
At sea level, standard barometric pressure is taken as
101.325 k.Pa, equivalent to an absolute pressure of
14.696 Ibfin.~2. It is also equal to the pressure exerted by
a mercury column 760 mm (29.92 in.) high ~ that is,
equal to 760 mm Hg (29.92 in, Hg) or 760 torr, 1
attenuation: (1) Decrease in energy or signal magnitude in
transmission from one point to another. Can be
expressed in decibels or as a scalar ratio of the input
magnitude to the output magnttude.t-'" (2) The loss in
acoustic energy that occurs between any two points of
travel. This loss may be caused by absorption, reflection, scattering or other material eharaetenstics.l''
(3) The change in signal strength caused by an electronic device such as an attenuator.? (4) In radiography,
the decrease in exposure rate of radiation caused by
passage through matertal.!'
attenuation coefficient: A factor which is determined by
the degree of diminution in sound wave energy per unit
distance traveled. Composed of two parts, one (absorption) proportional to frequency, the other (scattering)
dependent on the ratio of grain size or particle size to
wavelength.',18
attenuator: A device for causing or measuring attenuation.
Usually calibrated in deeibels.U?
austenite: A solid solution with iron as the solvent in a face
centered cubic structure formed by slow cooling of
delta ferrite. Characteristic lattice structure is stable
between 906 "C (1,663 OF) and 1,390 "C (2,535 OF).
Also called gamma iron. 8
automated system: Acting mechanism that performs
required tasks at a determined time and in a fixed
sequence in response to certain conditions."
B
B-scan: A data presentation method typically applied to
pulse echo techniques. It produces a two-dimensional
view of a cross sectional plane through the test object.
The horizontal sweep is -proportional to the distance
along the test object and the vertical sweep is proportional to depth, showing the front and back surfaces and
discontinuities between.',12
back draft: A reverse taper on the pattern that prevents its
removal from the mold."
back reflection: The signal received from the far boundary
or back surface of a test object.'·lo
back scatter: See backscatter. .
background: The surface of the test object on which the
indication is viewed in surface methods such as liquid
penetrant and magnetic particle testing. It may be the
natural surface of the object or the developer coating
on the object surface. This background may contain
irrelevant information that can interfere with the visibilitv of the indication. 2.6.16
backgr~und contamination: Tracer gases that accumulate in the test area, making it difficult to keep a leak
detector zeroed. They may also be a health hazard. 1
background cylinder and difference cylinder: Two
devices used to calculate illuminance by using the
equivalent sphere illumination technique. S,19
NONDESTRUCTIVE TESTING GLOSSARY I
bead: A half-round cavity in a mold or a half-round p[()ie!li!:ml
tion or molding on a casting,"
over the general surface of the test object during fluorescent penetrant testing and fluorescent magnetic parbeam exit point: See probe index.
ticle testing. 2
beam spread: The divergence of the sound beam as it
background noise: The signals that originate from the test
through a medium.l? Specifically, the solid angle _
object, the test instrument and their surroundings and
contains the main lobe of the beam in the far field. I
that interfere with test signals of interest It has electribearding: See furring,
cal and mechanical origins. Sometimes called grass or
.. bed-in: A method of ramming the drag mold with()tit
hash. 5,7J0
.
3
background signal: A steady or fluctuating output signal . ~~lling over it.
bedOing.a core: Placing an irregularly shaped core
of a test instrument caused by the presence of acoustic,
bed.:oFSand
for drying. 3
chemical, electrical or radiation conditions to which the
,
bentonite: A plastic, adhesive clay that swells when
sensing element responds. I
is derived from decomposed volcanic ash and is
backing board: A second bottom board where molds are
for
opened.f
- bondinz
.
b rnoldinz
.
b sand."
backscatter: (1) In radiography, radiation scattered from
Berthold penetrameter: A magnetic flux indicator conthe floor, walls, equipment and other items in the area
tainingan artificial discontinuity in the shape of a
of a radiation source. II (2) In ultrasonic testing, scatmounted below an adjustable cover plate. 6.l 5
tered signals that are directed back to the
beta particle: An electron or positron emitted from a
transmitter/receiver, i
nucleus during decay. I I
baked core: A core that has been heated or baked until it is
beta ray: A stream of high speed electrons of nuclear
thoroughly dry. 3
gin. This radiation is more penetrating than alpha
baked penneability: The property of a molded mass of
ation but ionizes less strongly.ll
w
lJ
sand heated at a temperature above 110°C (230 OF)
betatron:
A
circular
electron
accelerator
that
is
a
sourceiJ
until dry and cooled to room temperature to permit
either high energy electrons or X-rays. The electrons
passage of gasses. 3
are injected by periodic bursts into a region of an
band pass fIlter: An electromagnetic frequency filter that
nating magnetic field. After acceleration, the electro
has a single transmission band between two cutoff freare
brought out directly or directed against a target
quencies, neither of the cutoff frequencies being zero
produce
Xsrays.'!
or infinity.4,14
billet:
A
solid
semifinished round or square product tr. !.•~.
bandwidth: The difference between the lower and upper
has
been
hot
worked for forging, rolling or extrusion.' ,,~
cutoff frequencies,4.I4
binary system: In metallurgy, a two element alloy system."
barium clay: A molding clay containing barium, used to
eliminate or reduce the amount of scattered or secbin~e.r.: A material use~ to hold the grains. of san.• d toge.th.··•. l
ondary radiation reaching the film.:>
m molds or cores. It mav be cereal, 011, clav or natui • ~
or synthetic resins.I
'
.....
barometer: Absolute pressure gage used to measure the
atmospheric pressure at a specific location. I
birefringence: The splitting of a light beam into two
barometric pressure: Ambient pressure caused by the
through a translucent material.f
weight of the Earth's atmosphere. I See atmospheric
black body: See blackbody.
pressure.
black li~ht: Disfav~red term for elec.tromagnetic .radiati0J
baseline: The horizontal trace across the A-scan cathode
or light energy m the near ultraviolet range with wav~
ray tube display. It represents time and is generally
lengths from 320 to 400 nm, just below the wavelengtm
related to material distance or thickness.'
of visible light. Also a term for the ultraviolet light
basin: A cavity on top of the cope into which metal is poured
source used in fluorescent
nondestructive
testirl
.
:'1
before it enters the sprue. Also called pouring basin. 3
Black light sources often have a predominant wa\;.;.~
basis calibration: Standardizing an ultrasonic testing
length of 365 nm. See the preferred term, ultraviolet
instrument using calibration reflectors described in an
radiation. 2.6.S.16
.1
application document.'
black light filter: A filter that transmits ultraviolet radiati
bath: The water or oil used as a vehicle for wet method
between 320 and 400 nm wavelengths while absorbing or
magneticparticles." The liquid penetrant testing matesuppressing the transmission of the visible radiation
rials (penetrant, emulsifier, developer) into which test
hard ultraviolet radiation with wavelengths less
objects are immersed during the testing process and
320 nm. 6.I6
penetrant materials retained in bulk in immersion tanks
intended for reuse.f See suspension.
black light intensity: See intensity.
background fluorescence: Fluorescent residues observed
I,
520 I NONDESTRUCTIVE TESTING OVERVIEW
blackbody: Hypothetical radiation source that yields the
boreseope, anguIated: Borescope bent for viewing at for-
maximum radiation energy theoretically possible at a
given temperature. A blackbody will absorb all incident
radiation falling upon it and has an emissivity of 1.0. See
also emissivity. 9
blacklight: See black light.
bleed: Refers to molten metal oozing out ofa casting.
Stripped or removed from the mold before complete
ward oblique, right angle or retrospective angles for
visual testing of surfaces not accessible with conventional borescopes."
boresoope, fiber optic: Borescope that uses fiber optic
materials (such as glass or quartz) in the optical path
and for transmission of light to and from the test sur-
solidification.P
bleedback: The ability of a penetrant to bleed out of a dis-
boreseope, miero-j Borescope with an outside diameter
generally from 1 to 5 min (0.04 to 0.2 in.), typically
continuity subsequent to removal of the indication
without reapplying the penetrant.f
bleedout: The action by which a penetrant exudes from
discontinuities onto the surface of a material. Action of
the entrapped penetrant in spreading out from surface
discontinuities to form an indication.s
blended sand: A mixture of sands of different grain sizes
and clay content that is needed to produce a sand possessing more suitable characteristics for foundry use."
blind riser: An internal riser that does not reach to the
'j
exterior of the mold.?
Jblind spot: Portion of the retina where the optic nerve
enters, without rods and cones and hence insensitive to
'J
light,s
lblister: A discontinuity in metal, on or near the surface,
resulting from the expansion of gas in a subsurface
zone. Very small blisters are called pinheads or pepper
1
blisters.?
..
blotch: (1) An irregularly spaced area of color change on a
surface. (2) Nonuniform condition of a surface eharac)
terized by such blotches."
blotting: The action of the developer in soaking up the penetrant from the surface of a discontinuity so as to cause
If
~aximum bleedout of 0e. l~quid penetrant for
I Increased contrast and sensitivityblowhole: A hole in a casting or a weld caused by gas
1
entrapped during solidification.V'
blue hazard: Exposure to high frequency visible light at
i intensities and durations that may damage the retina,
particularly in conjunction with overheating,"
pobbin coil: See ID coil.
~ond: A cohesive material used to bind sand."
bond clay: Any clay suitable for use as a bonding material
I in molding sand."
.
?ond strength: The degree of cohesiveness that the bond, ing agent exhibits inholding sand grains together'
~ook mold: A split moldhinged like a book. 3
ilorescope: An industrial endoscope; a periscope or tele, scope using mirrors, prisms, lenses, optic fibers or television wiring to transmit images from inaccessible
interiors for visual testing. Originally used in machined
apertures such as gun bores. There are both flexible
and rigid, fiber optic and geometric light borescopes.f
face. s
using quartz filaments. Compare borescope, miniature. I>
boreseope, miniature: Borescope with an outside diameter generally less than 13 mm (0.5 in.). Sometimes
called miniborescope. See also borescope, micro-. 8
borescope, rigid: Borescope that does not bend; typically
in order to keep the geometrical optics in alignment
through a light train system,"
boreseope, ultraviolet: Borescope equipped with ultraviolet lamps, filters and special transformers to transmit
radiation of ultraviolet wavelengths. s
bottom board: The board or plate on which the mold
rests."
bottom echo: See back reflection.
bottom pour mold: A mold grated at the bortom.'
boundary echo: A reflection of an ultrasonic wave from an
interface. 7J2
branch gates: Gates leading into a casting cavity from a
single runner and sprue.P
brazing: Joining of metals and alloys by fusion of nonferrous alloys that have melting points above 430°C
(806°F), but below melting points of materials being
joined.f
bridging: Premature solidification of metal across a mold
section before the metal below or beyond solidifies. 3
brlnell hardness: A measure of metal hardness. Determined by pressing a hard steel ball into the smooth surface under standard conditions.
brlnelling: Stripe indentations made by a spherical object.
False brinelling refers to a type of surface wear,"
brittle crack propagation: A very sudden propagation of a
crack with the absorption of no energy except that
stored elastically in the body. Microscopic examination
may reveal some deformation even though it is not visible to the unaided eye,2
brittleness: The quality of a material that leads to crack
propagation without appreciable plastic deformation.S
broad banded: Having a relatively wide frequency bandwidth. Describes pulses that display a wide frequency
spectrum and receivers capable of amplifying them.
Opposite to narrow banded or tuned."
bubbler: See water column.
bucking coils: See differential coils.
buckle: Indentation in a casting, resulting from expansion
of the sand.?
NONDESTRUCTIVE TESTING GLOSSARY I
bumper: A machine used for packing molding sand in a
flask by repeated jarring or jolting. 3
bumping: Ramming sand in a flask by repeated jarring and
ca~a:::~~:~~:;: :Xq~~'r.:6b~:
sures. The positive force that causes movement
tain liquids along narrow or tight passages. 2
carrier fluid: (1) A fluid that acts as a carrier for the
burning: Extreme overheating. Makes grains excessively
materials. (2) The fluid in which fluorescent and visil»
large and causes the more fusible constituents of steel
to melt and run into the grain boundaries or it may
dyes are dissolved or suspended, in liquid pe. n.etr.anl.f
.••.~. '•.: O(
leak tracers.' (3) The liquid vehicle in which flu(.·ts
leave voids between the grains. Steel may be oxidized to
cent or non£1uorescent magnetic particles are sus
the extent that it is no longer good and cannot be COF,
;...pended for ease of application. See vehicle. 6,16
rected by heat treating but it can be remelted.f
'.~
burnt-in sand: A discontinuity consisting of a mixture of
case '~~shing: A mechanism producing fracture
sand and metal cohering to the surface of a casting."
case; like subcase fatigue but attributable to static
burr: A raised or turned over edge occurring on a machined
loading rather than to fatigue alone. In many inst~ce
part and resulting from cutting, punching or grinding. 8.19
the m.ovement of the .subcase causes the case to i.· el
or spall."
•••.
burst: (1) A signal whose oscillations have a rapid increase
casing: The many strings of pipe that are used to line thl
in amplitude from an initial reference level (generally
hole during and after drilling of a gas or oil welLS 0'.• .]
that of the background noise), followed by a decrease
casing string: Tubular structure on the outer perimetlil 0
(generally more gradual) to a value close to the initial
a gas or oil well hole. The casing string is a permanen
value/' (2) In metal, external or internal rupture caused
by improper forming."
~art ~f the well and many are cemented into the
b~.
,
burst counting: A measurement of the number of bursts
cassette: A lightproof container that is used for holding".l
detected relative to specified equipment settings such
as threshold level or dead time.f
radiographic films in position during the radiographf
burst duration: The interval between the first and last time
exposure and that mayor may not contain intensii".1ni
the threshold was exceeded by the burst:5
and/or filter screens. 11
<,I
burst emission: A qualitative term applied to acoustic emiscast structure: The internal physical structure of a castin:
sion when bursts are observed.s
~~~~~:p~~~~:)~' orientation of grains and seguJ,a
burst rate: The number of bursts detected in a specified
time.f
cast weld assembly: An assembly formed by welding'~nl
burst rise time: The time interval between the first threshcasting to another.'
old crossing and the maximum amplitude of the burst.P
casting: Object of shape obtained by solidification of a
butt weld or butt joint: Weld joining two metal pieces in
stance in a mold.
casting shrinkage: Total shrinkage includes the sum 0
the same plane."
three types; (1) liquid shrinkage (the reduction inffl
ume of liquid metal as it cools to the liquidus); (2) s:.,jJd
ification shrinkage (the change in volume of metal fron
C-scan: A data presentation technique applied to pulse
the beginning to ending of solidification); and (3)
echo and transmission techniques. It yields a twoshrinkage (the reduction in volume of metal frorr.
dimensional plan view of the object but no depth indisolidus to room temperaturej.F'
cations unless special gating procedures are used.7.l0.12
casting strainsi Strains in a casting caused by castin:
calibration reflector: A reflector with a known dimenstresses that develop as the casting cools.3
sioned surface established to provide an accurately
casting stresses: Stresses set up in a casting bel~a1JlsL&I! 0
reproducible reference level.?
geometry and casting shrinkage.'
candela: Base unit of measure in $1 for measuring luminous intensity. The luminous intensity in a given direccathode: (1) In radiography, the negative electrode
tion of a source that emits monochromatic radiation of
electron tube. (2) Positively charged terminal
frequency 540 x 1012 Hz and that has a radiant intensity
arrangement that produces current by chemical
in that direction of 1.4641 mW·sr~l. Symbolized cd.
tions. Compare anode.s .
Formerly known as candle. 8
cathode ray: A str~am of ~lectronsemitted bya heatectrl
candle: Former name for candela. I>
ament and projected m a more or less confined b~,lln
capacitor discharge technique: A single-shot magnetizaunder the influence of a magnetic or electric field. 7•12
tion technique using discharge from a bank of capacitors.
cathode ray tube (CRT). A vacuum tube containi;~
A means by which electrical charge is built up and stored
screen on which nondestructive testing or other si&ii~
until a sufficient level is achieved to provide a predetermay be displayed. Used for ultrasonic A-scans' 0
B-scans.7,12
mined magnetic field in a test object, usually saturation."
jolting,"
c.l.•.
fo!;a
c
522 I NONDESTRUCTIVE TESTING OVERVIEW
cavitation fatig-ue: A form of pitting caused by erosion
chuck: A small bar set between crossbars to hold sand in
from vibration and movement in liquid environments.f
cavity: The die impression that gives a casting its external
circular magnetic field: The magnetic field surrounding
shape.'
eeD: See charge coupled device.
cementite: Iron carbide (Fe3C), present in steels."
central conductor: An electric conductor passed through
the opening in a part with an aperture, or through a
hole in a test object, for the purpose of creating a circular magnetic field in the object.6 •10
centrifugal casting: A casting made in a mold (sand, plaster or permanent) that rotates while the metal solidifies
under the pressure developed by centrifugal force. 3
certification: The process of providing written testimony
that an individual is qualified. See also certified. 8
certified: Having written testimony of qualification. See
... .
also certification. 8
lchafmg: See wear,fretting.
.
'chalk test: A past method of locating cracks by applying
penetrating liquid to an object and then removing the
excess from the surface. The surface is coated with
whiting or chalk. After a short period of time the penetrant seeps out of the cracks into the whiting or chalk,
~j
causing an appreciable difference in whiteness.f
\chan?els: .In biol~gy, mechanisms functioning ~s bandJ?~ss
fllters In the visual cortex of mammals, causIng sensttrvity to visual stimuli in particular frequencies and
1 ranges. S
..
.
chaplet: A metal support used to hold a core in place on a
mold?
..
fharg~ coupled ~e~ce (e~D): Solid state image sens~r
1
WIdely used In inspection systems because of 0eIr
accuracy, high speed scanning and long service life. s
eharpy test: A destructive mechanical test in which a
1 notched 10 x 10 x 55 mm rectangular bar, supported at
i
both ends as a Simple beam, is broken by the impact of a
falling pendulum. Energy absorbed in breaking the bar is
a measure of the impact strength of the bar material and
j
indicates the material's resistance to brittle fracture."
chatter: (1) In machining or grinding, a vibration of the
I
tool, wheel or workpiece producing a wavy surface on
\ the wor~. (2) The finish produce? by such vibration.f
checks: Numerous, very small cracks In metal or other material caused in processing. Minute cracks as in a die
impression, usually at a comer, caused by forging strains.
Also called grinding checks and check marks."
chill: (1) A metal insert embedded in the surface of a sand
mold or core or placed in a mold cavity to increase the
cooling rate at that point. (2) White iron occurring on a
gray iron casting, such as the chill in the wedge test. 3
('.,hipping: (1) Removing seams and other surface disconti. . nuities in metals manually with chisel or gouge or by
continuous machining, before further' processing.
.
(2) Removing excessive metal. 2.3
the cope.'
an electrical conductor (test object) when a current is
passed longitudinally through the conductor. 6.l 6
circular magnetization: The magnetization in an. object
resulting from current passed longitudinally through
the object itself or through an inserted central conductor. 6 ,16
circumferential coil: See encircling COil.
circumferential magnetization: See circular magnetization.
eire perdue process: The lost wax process. 3
clean: Free from interfering solid or liquid contamination
On the test surface and within voids or discontinuities.f
cleaner: Volatile solvent employed to clean a surface before
penetrant application. The cleaner is sometimes referred to as the solvent removerf
cleanup or cleanup time: The time required for a leak
testing system to reduce its signal output to 37 percent
of the signal indicated when the tracer gas ceases to
enter the leak testing system.!
cleavage: The fracture of a crystal on a crystallographic
plane of low index."
cleavage fracture: A fracture, usually of a polycrystalline
metal, in which most of the grains have failed by cleavage, resulting in bright reflecting facets. It is one type of
crystalline fracture. Contrast with shearfracture. 2
closing: In image processing, dilation followed by erosion.
A Single pixel closing connects a broken feature separated by one pixel. See also opening. S
closure: Process by which a person cognitively completes
patterns or shapes that are incompletely perceived. 8
cocoa: Debris (usually oxides of the contacting metals) of
fretting wear, retained at or near the site of its formation - a condition especially helpful during visual tests.
With ferrous metals, the debris is brown, red or black,
depending on the type of iron oxide formed. For this
reason, ferrous debris is called cocoa or, when mixed
with oil or grease, red mud. 8
code: A standard enacted or enforced as a law.s
coefficient of thermal expansion: The linear expansion
or contraction per unit length per degree of temperature change between specified lower and upper temperature limits. 2
coefficients of the filter: Values in a mask that serves as a
filter in image processing."
coercive force: The reverse magnetizing force needed to
remove remanent or residual magnetism and thereby
demagnetize the object."
coil: One or more loops of a conducting material. In eddy
current testing, a Single coil may be an exciter and
induce currents in the material or it may be a detector
or both simultaneously"
NONDESTRUCTIVE TESTING GLOSSARY I
coil clearance: See liftoff
coil shot: A technique of producing longitudinal magnetization by passing electric current through a coil encircling the test object. 6 ,10
coil spacing: In electromagnetic testing, the axial distance
between two encircling coils of a differential system. 4 ,13
coil technique: A method of magnetization in which ail or
a portion of the object is encircled by a current-carrying
"
coil.6,16
cold cathode ionization gage: Discharge current results "~
from the application of a high voltage between anode
and cathode. The discharge current magnitude is a
function of the gaseous pressure within the gage chamber. The external permanent magnet facilitates ionization by forcing the electrons into a spiral path between
the two electrodes. The discharge current is displayed
on a meter over the absolute pressure range of less than
10 mPa (10-4 torr).1 Also known as Philips discharge
gage or Penning gage,
.
cold chamber machine: A die casting; machine where the
metal chamber or plunger are not heated. 3
cold cracks: Discontinuities appearing as straight lines usually continuous throughout their length and generally
existing singly. Cold cracks start at the surface and result
from cold working or stressing of metallic matenals.f
cold light: Obsolete word for fluorescence. 8
cold shut: (1) Casting discontinuity caused bv two streams
of semimolten metal coming tO'gether inside a mold but
failing to fuse. Cold shuts are sometimes called misruns
but the latter term correctly describes incomplete filling of the mold? (2) A discontinuity that appears on the
surface of test metal as a result of two streams of liquid
meeting and failing to unite, A cracklike discontinuity
caused by forging, where two surfaces of metal fold
against each other to produce a discontinuity at the
point of folding, This is usually at some angle to the surface. It may also be a separate piece of metal forged
into the main component. See lap, (3) A portion of the
surface of a forging that is separated in part from the
main body of metal by oxide.t-'
cold work: Permanent deformation produced by an external force in a metal at temperature below its recrystallization temperature.?
collimator: A device for limiting effects of beam spread."
color: Visual sensation by means of which humans distinguish light of differing hue (predominant wavelengths),
saturation (degree to which-those radiations predominate over others) and lightness.
color blindness: Deficiency in the ability to perceive or
distinguish hues.f
color contrast dye: A dye that can be used in a penetrant
to impart sufficient color intensity to give good color
contrast indications against the background on a test
surface when viewed under visible light.Z
incorporati,i'~[l
color contrast penetrant: A penetrant
dye, usually nonfluoresoent, sufficiently intensive ti
~~i~I~O~~jSibility to discontinuity indications u~fe
color discrimination: The perception of difference
between two or more hues."
columnar structure: A coarse structure of parallel colt~lI1
of grains, having the long axis perpendicular to the
ing surfaceP
cQ.mbination die: A die having two or more different
t~:t(lr different castings,"
comparative measurement: In electromagnetic testinjl2;,
measurement based on the unbalance in a system
comparator coils. In contrast to differential and
lute measurements. See also comparator coils. 4.13
comparative test block: A penetrant comparator in th.
form of a block See comparator, penetrant.
comparator coil: In electromagnetic testing, two or
coils electrically connected in series opposition all!
arranged so that there is no mutual induction (,s""U
pIing) between them. Any electromagnetic cond/lo:
that is not common to the test object and the stamran
will produce an unbalance in the system and thereb
I
yield an indication. See differential coils. 4,13
comparator, penetrant: A test block or reference Fhf
with artificial cracks or special surface conditions, typi
cally having tw.o.se.-.p.ar.ate b.ut adjacent ar.eas for apF,',l.';.',f"a
tion of different penetrants or processing materia ,I a
operation, so that a direct visualcomparison can be mad
between different penetrant processes or materials.j
compensator: An electrical matching netwo::k"to com i~ll
sate for electrical impedance differences. 1,1-J
complete testing: Testing of an entire production lot in
prescribed manner. Sometimes complete testing erifil
the inspection of only the critical regions of a part. In
hundred percent testing requires the inspection of th
entire _pari by prescribed methods. Compare sampT-i~1e
.
partial. 8
.1
complex plane: A plane defined by two perpendicular-eel
erence axes, used for plotting a complex variable (sue
'as impedance) or functions of this variable (such
transfer function). See impedance analysis.4.l-4
compound microscope: See microscope, compound.
compressional wave: A wave in which particle motic ,i
the material is parallel to the wave propagation d ~c
tion. Also called longitudinalwave.7
conditioned water: Water with an additive or additiye
that impart specific properties such as proper wet )1§
particle dispersion or corrosion resistance.f
I
conditioning agent: An additive to water suspensions ths
imparts specific properties such as proper wetting,
ticle dispersion or corrosion resistance. 6,16
conductance: Property of a gas flow system that permi1
gas to flow. 1
I
NONDESTRUCTIVE TESTING OVERVIEW
'771
_.-.;:rnduction: Heat transfer occurring when warmer atomic
'-~
particles collide with - and thus impart some of their
heat energy to - adjacent cooler (slower moving) particles. This action is passed on from one atom (or free
electron) to the next in the direction of cooler regions.
Thus, heat always flows from a warmer to a cooler
region. 9
In biology, a retinal receptor that dominates the retinal response when the luminance level is high and pro_ vides the basis for the perception of color. Compare
~71 rod. 8,20 _
_
_
.
bnfidence level: The probability that the true leakage
rate will not exceed the upper confidence limit.'
"pnstitution diagram: See phase diagram.
pntact head: Electrode assembly used to clamp and support an object to facilitate passage of electric current
o
through the object for circular magnetization. 6.l 6
~ntact method: (1) The ultrasonic testing method in
1 which the transducer makes direct contact with the test
object through a thin film of couplant. 7,12 (2) The cur'-1 rent flow technique in magnetic particle testing. 6
~ntact pad: Replaceable metal pad, usually made of lead
or copper braid, placed on electrodes to give good elec'I trical contact, thereby preventing damage such as arc
j strikes to the test object. 6 . 16
cdntact transducer: The transducer used in the contact
. method.'
• jntinuous annealing furnace: A furnace in which castings are heat treated, by being passed through different
heat zones kept at constant temperatures.P
( "jDtinuous casting: A casting technique in which an ingot,
j billet, tube or other shape is continuously solidified
while being poured so that its length is not determined
. by mold dimensions.f
( ptinnous emission: A qualitative term applied to acousi tic emission when the bursts or pulses are not discemible."
cpnnuous technique: Applying of magnetic particles to
\ form satisfactory discontinuity indications while the
magnetizing field is simultaneously applied,"
tir~.uous .wave: A .sin~le frequency wave that continues
I WIthout interruption. '
cuntracted sweep: A misnomer that refers to extending
the duration of the sweep to permit viewing discontinuities or back reflections from deeper in the test object.
The sweep appears to be compressed.'
eontrasti (1) In radiography, the measure of differences in
the film blackening resulting from various radiation
intensities transmitted by the object and recorded as
density differences in the image: Thus, difference in
film blackening from one area to another. 11 (2) The difference in visibility (brightness or coloration) between
an indication and the surrounding surface.' ,
eontrol: See in control, process control and quality control.
o-
ie-.r.•'
control echo: A reference signal from a constant reflector,
such as the back reflection from a smooth, regular surface. 7,12
cooling stresses: Residual stresses resulting from nonuniform distribution of temperature during cooling. 2,3
cope: The upper or topmost section of a flask, mold or pattem.'
core: (1) A specially formed material inserted in a mold to
shape the interior of another part of a casting that cannot be shaped as easily by the pattern. (2) In a ferrous
alloy, the inner portion that is softer than the outer portion or case." .
core blower: A machine for making foundry cores, using
compressed air to blow and pack the sand into the core
box.3
core pin: A core, usually a circular section, having some
taper or draft."
core plate: A plate on which a green core is baked.?
core wash: A liquid with which cores are painted to produce smoother surfaces on the casting. 3 ·
corner effect: The strong reflection obtained when an
ultrasonic beam is directed toward the intersection of
two or three mutually perpendicular surfaces. 7,12
corrosion: The deterioration of a metal by chemical or
electrochemical reaction with its environment.
Removal of material by chemical attack, such as the
rusting of automobile components.f
corrosion, crevice: Type of galvanic corrosion caused by
differences in metal ion concentrations in neighboring
portions of the corrodent,"
corrosion embrittlemenn The severe loss of ductility of a
metal, resulting from corrosive attack, usually intergranular and often not visually apparent. 2
corrosion fatigue: Fatigue cracking caused by repeated
load applications on metal in a corrosive environment.f
corrosion, fretting: Corrosion facilitated by fretting, particularly where a protective surface has been chafed in
a corrosive environment. 8
corrosion, poultice: Corrosion occurring under a layer of
foreign material (e.g., under mud in automobile rocker
panels),"
corrosion-erosion: Simultaneous occurrence of erosion
and corrosion.f
count rate: See acoustic emission rate.
couplant: A substance (usually liquid) used between an
ultrasonic transducer and the test surface to permit or
improve transmission of ultrasonic energy into the test
objectY2
coupled: Two electric circuits that have an impedance in
common so that a current in one causes a voltage in the
other. 4 ,13
coupling: The percentage of magnetic flux from a primary
circuit that links a secondary- circuit. The effectiveness
of a coil in inducing eddy currents in the test object,"
0
0
NONDESTRUCTIVE TESTING GLOSSARY I 525
coupling coefficient: (1) The fraction of magnetic flux
from one test coil that threads a second circuit (test
object). (2) The ratio of impedance of the coupling to
the square root of the product of the total impedances
of similar elements in the two meshes.v-"
coupon: A piece of metal from which a test object is prepared, often an extra piece, as on a casting or forging,3
cover half: The stationary half of a die casting die. 3 .
crack: (1) A break, fissure or rupture, usually V shaped and
relatively narrow and deep, A discontinuity that has a
relatively large cross section in one direction and a
small or negligible cross section when viewed in a direotion perpendicular to the first,2 (2) Propagating discontinuities caused by stresses such as heat treating or
grinding. Difficult to detect unaided because of fine~
ness of line and pattern (may have a radial or latticed
appearance),6
crack contaminant: Material that fills a crack and that may
prevent penetrants from entering or from forming indications.s
crack, base metal: Cracks existing in base metal before a
manufacturing or welding operation or occurring in
base metal during the operation.f
crack, cold: Cracks that occur in a casting after solidification, due to excessive stress generally resulting from
nonuniform cooling. 2
crack, cooling: Cracks in bars of alloy or tool steels resulting from uneven cooling after heating or hot rolling.
They are usually deep and lie in a longitudinal direction, but are usually not straight 2
.
crack, crater: A multisegment crack in a weld crater. Segments radiate from common point, often called star
cracks.
crack, fatigue: Progressive cracks that develop in the surface and are caused by the repeated loading and
unloading of the object.f
crack, forging: Cracks developed in the forging operation
due to forging at too low a temperature, resulting in
rupturing of the steel. 2
.
crack, grinding: Thermal cracks caused by local overheating of the surface being ground,2
crack, hot: Cracks that develop before the casting has completely cooled, as contrasted with cold cracks, that
develop after solidification. 2
crack, longitudinal: Cracks parallel to the length of the
test object,2
crack, machining: Cracks caused by too heavy a cut, a dull
tool or chatter, Typically called machining tears. 2
a
crack, pickling: Cracks caused by immersing objects with
high internal stresses in an acid solution,2
crack, plating: Cracks similar to pickling cracks, but occurring during plating when the object is immersed in a
strong electrolyte.s
quenchiJ~~J
crack, .quenching: Ruptures produced during
of hot metal due to more rapid cooling and contraction
of one portion of a test object than occurs in ad'jaoerllil
portions.f
crack, transverse: Cracks at right angles to the length
the test object. 2
.
.7>
crack, weld: Cracks in weld fusion zones o~ adjacent basi.'
metal, Usually a result of thermal expanSIOn or contrao."J
..
tion stresses related to temperature changes during
-1
"~ ~lding. 2
crater: ('b).lp machining, a depression in the cutting tocl
faceeroded by chip contact (2) In arc or gas fusion
welding, a cavity in the weld bead surface: typicall~~
occurring when the heat source is removed and jnsuffi~l~
cient filler metal is available to fill the cavity.2'
creep: Gradual and permanent change of shape in a met~,
under c.onstant load, usu~y at elevated. temperaturE·"~
Occurs III three stages: pnmary creep, secondary cree... >J
and tertiary creep. See also deformation. 8
.
creep strength: The constant nominal stress that will
a specified creep rate at constant temperature.f
crevice corrosion: See corrosion, crevice.
critical angle: .The in._c.i~ent angle of an u.ltrasoun.d bearp].:.
above which a specific mode of refracted energy n :
longer exists.7JO .,.:
cross line grating: In moire and grid nondestructive testing, a grating with bars, furrows or lines parallel
orthogonal xy axes.?
cross talk: The unwanted signal leakage (acoustical or electrical) across an intended barrier, such as leak
between the transmitting and receiving elements of
dual transducer. Also called cross noise and cross c piing. i,12
CRT: See cathode ray tube.'~
crush: A casting discontinuity caused by a partial destruc . •J
tion of the mold before the metal was poured.'
crushing: T.he pushin.g out of shape of a sand core or sanl.'.•.•. .•.~
mold when two parts of the mold do not fit properl.J
where they meet. 3
."
crystal: See transducer:
crystal mosaic: Multiple crystals mounted in the
plane on one holder and connected so as to cause all
vibrate as one unit,i,12
crystal, X-cut: A cut such that the cut face isperpendicu I~
lar to the X-direction of the piezoelectric crystal. In , . 1
quartz slice so cut, a thickness mode of vibration
occurs when the slice is electrically stimulated in th(' \
X-direction.7,12:1
crystal, Y-cut: In Y-cut, the cut face of the piezoelectric #
crystal is perpendicularto the Y-direction. In quartz,
shear mode of vibration is obtained when the slice
electrically stimulated in the Y~direction.7.l2
cumulative bursts: The number of bursts detected from
the beginning of the test. 5
..
.
526 I NONDESTRUCTIVE TESTING OVERVIEW
cumulative characteristic distribution: A display of the
number of times an acoustic emission signal exceeds a
preselected characteristic as a function of the eharacteristic.P
cumulative count: The number of times the amplitude of
an acoustic emission signal has exceeded the threshold
since the start of a test. 5
cumulative events: The number of events detected from
the beginning of a test. Use of this term is restricted in
the same way as event counting,"
cup fracture: Fracture, frequently seen in tensile test
places of a ductile material, in which the surface of failure on one portion shows a central flat area of failure in
tension, with an exterior extended rim of failure in
shear. Also called cup-and-cone fracture. 2
Curie point; The temperature at which ferromagnetic
materials lose residual magnetism and can no longer be
magnetized by outside forces (between 650 and 870°C
[1,200 and 1,600 OF] for most metals).6.16
current flow technique: Magnetizing by passing current
through an object using prods or contact heads. The
current may be alternating current or rectified alternating current.6.16
curre.nt in~uction tec~~iq.uei M.a.gne~z.ation in Which a
.
circulating current IS induced m a nng component by
the influence of a fluctuating magnetic field. 6.l6
cutoff frequency: Upper or lower spectral response of a
filter or amplifier, at a specified amount less (usually 3
or 6 dB) than the maximum response.'
cycle: A single period of a waveform or other variable. See
1
period.:
I
o
damping: (1) Limiting the duration or decreasing the
amplitude of vibrations, as when damping a transducer
element.P (2) A deliberate introduction of energy
v
absorbers to reduce vibrations.'
damping capacity: A measure of ability of a material to
dissipate mechanical energy.7.1S
damping material; A highly absorbent material used to
I
cause rapid decay of vibration.'
ldamping, transducer: A material bonded to the back of
the piezoelectric element of a transducer to limit the
duration of vibrations.'.l°
damping, ultrasonic: Decrease or decay of ultrasonic
wave amplitude with respect to time or distance.v'?
dark adaptation: (1) Adjustment of the eye over time to
reduced illumination, including increased retinal sensitivity, dilation of the pupil and other reflex physical
changes. 2 .6.16 (2) Process by which the retina becomes
adapted to luminance less than about 0.034 cd·m-2. 8.2o
dark adapted vision: See scotopic vision.
daubing: The act offilling cracks in cores'
dead zone: In ultrasonic contact testing, the interval following the initial pulse at the surface-of a test object to
the nearest inspectable depth. lO Any interval following
a reflected Signal where additional Signals cannot be
detected.'
deburrlng: Removing burrs, sharp edges or fins from metal
objects by flling, grinding or rolling the work in a barrel
with abrasives suspended in a suitable liquid medium.
Sometimes called burring. 2.3
decarburization: The loss of carbon from the surface of a
ferrous alloy as a result of heating in a medium that
reacts with the carbon at the surface.f
decibel: A unit for expressing power relationships in sonic
and acoustic measurements. Equal to ten times the
base ten logarithm of the ratio of two powers. The unit
for voltages is twenty times the base ten logarithm of
the ratio Oftwo voltages, provided the voltages are measured across equal impedances.'
deep drawing: The forming of deeply recessed parts by
means of plastic flow of the materialf
deep etching: Severe etching of a metallic surface for
examination at a magnification of ten diameters or less
to reveal gross features such as segregation, cracks,
porosity or grain flow. 2
defect: A discontinuity whose size, shape, orientation or
location make it detrimental to the useful service of its
host object or which exceeds the accept/reject criteria
of an applicable specification.v'? Note that some discontinuities mav not affect serviceability and are therefore not defe~ts.2 All defects are dIscontinuities. 2
Compare discontinuity and indication. 8.19
deformation: Change of shape under load. See also creep
and elastic deformation. S
degasifier: A substance that can be added to molten metal to
remove soluble gases that might otherwise be occluded
or entrapped in the metal during solidification.?
degassing: Removing gases from liquids or solids.P
degreasing fluid: Solvents or cleaners employed to
remove oil and grease from test surfaces before the liquid penetrant is applied. 2
delamination: A laminar discontinuity, generally an area of
unbonded materials.'
'
,
delay line: A material (liquid or solid) placed in front of a
transducer to cause a time delay between the initial
pulse and the front surface reflection.'.l2
delayed sweep: An A-scan or B-scan sweep, the start of
which has been delayed, thereby eliminating the
appearance of early response data on the screen. 7.2.1
delayed time base: See delayed sweep.
NONDESTRUCTIVE TESTING GL.OSSARY 1527
detector probe: An adjustable or fixed device
delta effect: Reradiation of energy from a discontinuity.12
which air and/or tracer gas is drawn into the leak test
The reradiated energy may include waves of both inciinstrument and over the sensing element or de1:ecl:~81'
dent mode and converted modes (longitudinal and
shear),"
Also called a sampling probe or a sniffer probe. 1
detector probe test: A pressure leak test in which
delta ferrite: Solid solution with body centered cubic
leakage of a component, pressurized with a tracer ri .
structure and iron as solvent. Also called delta iron. 8
mixture, is detected by scanning the test object bou
delta iron: See delta ferrite.
ary
surface with a sniffer probe connected to an e
delta t (At): The time interval between the detected arrival ..
.
tronic
leak detector. Leakage tracer gas is pulled from
of an acoustic emission wave at two sensors.P
demagnetization: The reduction of residual magnetism to "
.
an acceptable leveL6.l6
the' real< test instrument.' Also called sniffer test.
demagnetizing coil: A coil of conductive material carrying
detergent r.emove.r: A penetrant
re.mover that is a. sOl.Util··
•.· . • .•.
alternating current used for demagnetization. 6,15
of a detergent in water. 2
);
demodulation: A modulation process wherein a wave
developer: (1) In penetrant testing, a material that IS
resulting from previous modulation is employed to
applied to the test piece surface after the excess pen~
derive a wave having substantially the characteristics of
trant has been removed and that i~d~si~ed to enham 1
the original modulating wave.v!"
the penetrant bleedout to form indications. May be J
dendrite: A crystal that has a treelike branching pattern,
fine powder, a solution that dries to form a dry powder
being most evident in cast metals slowlycooled through
or a..susp..e~sio~ (in solvent or w.ater) tfat dries l~avi1"··.l.• .
the solidification range. 2.3
an absorptive film on the test surface.f (2) In radiogr I
deoxidizing: (1) The removal of oxygen from molten metphy,a chemical solution that reduces exposed silver
als by use of suitable deoxidizers. (2) Sometimes refers
halide crystals to metallic silver.l l .
to the removal of undesirable elements other than oxydeveloper, dry: A dry, fine powder applied to the test piec J
gen by the introduction of elements or compounds th~t
after the excess penetrant is removed and the surface
readily react with them. (3) In metal finishing, the
dried in order to increase the bleedout by means of
removal of oxide films from metal surfaces bv chemical
capillary action.f
..
or electrochemical reaction.'
developer, nonaqueous: See developer, solvent.
developer, soluble: Fine particles completely soluble in its
depth compensation: See distance amplitude correction.
depth of field: In photography, the range of distance over
carrier (not a sus p. ension of powder .in a liquid) th".·.!:.l.•
dries to form an adsorptive coatmg."
,I
which an imaging system gives satisfactory definition
developer, solvent: Fine particles suspended in a volatile
when its lens is in the best focus for a specific distance."
solvent. The volatile solvent helps to dissolve the penedepth of fusion: The depth to which the base metal melted
trant
out of th~ dis~o.ntinui~ a~d ~rin~s it to the su
during welding.s
face.
It
then dries, flXlng the indication.f
depth of penetration: In electromagnetic testing, the
developer,
wet: A penetrant developer usually supplied as
depth at which the magnetic field strength or intensity
~ry
particle~
tha~ is mixed with water to form a suspeJj
of induced eddy currents has decreased to 37 percent
sion
of
partlcles.-.
. "J
of its surface value. The square of the depth of penetradeveloping
time:
Elapsed
time
necessary
for
the
applied
tion is inversely proportional to the frequency of the
de.v.eloper to abso~b and show indications from. pene-.·..
signal, the conductivity of the material and the permetrant
entrapments.'
;~l
ability of the material. Synonymous terms are standard
dewaxing: Removing the expendable wax pattern from a:ti
depth of penetration and skin depth. See joint penetrainvestment mold by heat or solvent,"
tion, root penetration and skin effect. 2.4.13
dewetting: The flow and retraction of liqu_id on a surfaei ]
descallng: Removing the thick layer of oxides formed on
caused by contaminated surfaces or dissolved surfac "I
some metals at elevated temperatures.i
coatings."
deseaming: Analogous to chipping, the discontinuities
diamagnetic
material: A material whose relative perm€'
being removed by gas cutting. 2 .
ability is less than unity. The intrinsic induction B;
detail: In radiography, the degree of sharpness of outline of
oppositely directed to applied magnetizing force
the image. If a radiograph does not show a clear definiA material with magnetic permeability less than 1.6
tion of the object or a discontinuity in the object, it is of
die casting: (1) A casting made in a die. (2) A casting pH
little value although it may have sufficient contrast and
cess where molten metal is forced under high pressUl
density.!l
into the cavity of a metal mold. 3
detector coil: See sensing coil.4
difference cylinder: See background cylinder.
~ ~:J:~~~r~~11e~~ ~~:bl~n~~~~~: St~:si~~~I:t~:I;']
528 / NONDESTRUCTNE TESTING OVERVIEW
differential amplifier: An amplifier whose output signal is
proportional to the algebraic difference between two
input signals. 4 ,14
!!:;t~idiffe~:~~y ~:~~~pi::c~~s~:::e~;:;~~~~ri:~j~~;~~i~;~
such that an unbalance between them, causing a signal,
will be produced only when the electromagnetic conditions are different in the regions beneath two of the
coils. In contrast, comparator coils are not adjacent.'
differential measurement: In electromagnetic testing,
the imbalance in the system is measured using differential coils ~ in contrast to absolute measurement and
comparative measurement. 4,13
j;~n::~~d ;~~:~~~~let~tr~:ak;~~ ~~;~~' :~t:u~f
change with respect to time. 4.13
~'r'racoon: In ultrasonic testing, the deflection of a wave•.
fro.nt w~en passing the edge of an ultrasonically opaque
'
obJectI~
l.
diffuse indications: Indications that are not clearly
defi~ed. as, for example, indications from surface con• tamination."
diffuse reflection: Scattered, incoherent reflections from
rough surfaces. 7.l O
frrusion: The process b~ which ~olecules intermingl~ as.~
result of concentration gradients or thermal motion.Spreading ofa gas through other gases within a volume.
",.
UIa~on: In image pr?ces~ing, the c,' on~.ition ?f a b.inary
j Image where the pixel m the output Image IS a 1 If any
of its eight closest neighbors is a 1 in the input image.
'
\. See also closing, erosion and opening. 8
p rin~e: A means o~ removin~ exces~ surface penetr~nt in
which the test objects are dipped into a tank of.agitated
water or remover. 2
rec~ contact magnetization: See current flow techtuque.
direct' current: An electric current flowing continually in
t one direction through a conduetor.v'?
;rect current field: Ail active magnetic field produced by
direct current flowing in a conductor or COil. 6,I7
r
"l.•
.r"rec,t pho",tome,try: Sim,ultan,e~us comparI,8,20
'son of a, s"tandard lamp and an unknown light source.
ect substitution alloy: Alloy in which the atoms of the
alloying element Can occupy the crystal lattice spaces
normally occupied by the atoms of the parent metal,"
!.I·ect viewing: Viewing of a test object in the viewer's
immediate-presence. The term direct viewing is used in
the fields of robotics and surveillance to distinguish
\ conventional from remote viewing.8
direct vision instrument: Device offering a view directly
forward. A typical scene is about 19 rnrn (0.75 in.) wide
, at 25 mm (1 in.) from the objective lens."
.Jrectional lighting: lighting provided on the work plane
or object predominantly from a preferred direction. s,2o
.
I
directional properties: Properties whose magnitudes depend on the relation of the test axis to the specific
direction in the metal, resulting from preferred orientation or from fibering in the structure. See anisotropy. 2
directional solidification: The solidification of molten
metal in a casting in such manner that feed metal is
always available for that portion that is just solidifying.3
dlscernible image: Image capable of being recognized by
sight without the aid of magnification. 2
discontinuity: An intentional or unintentional interruption in the physical structure or configuration of a
part. 6•8,16.22 After nondestructive testing, unintentional
discontinuities interpreted as detrimental in the host
object may be called flaws or defects," Compare defect,
dislocation and indication.
discontinuity, artificial: Reference discontinuities such as
holes, indentations, cracks, grooves or notches that are
introduced into a reference standard to provide accurately reproducible indications for determining sensitivity Ievels.?
discontinuity, inherent: Material anomaly originating
from solidification of cast metal. Pipe and nonmetallic
inclusions are the most common and can lead to other
types of discontinuities in fabrication.f-'?
discontinuity, primary processing: Material anomaly
produced from the hot or cold working of an ingot into
forgings, rod and bar.8 .l 9
discontinuity, secondary processing: Material anomaly
produced during machining, grinding, heat treating,
plating or other finishing operations. S,19
discontinuity, service induced: Material anomaly caused
by the intended use of the part. 8
dislocation: Void or discontinuity in the lattice of a metal
crystalline structure.f Two basic linear types are recognized (edge dislocation and screw dislocation) but combinations and partial dislocations are most prevalent.i
dispersion: The variation of phase velocity with frequency. 7
dispersive medium: A medium in which propagation
velocity depends on the wave frequency.'
displacement resolution: In moire and grid nondestructive testing, measurement precision expressed as the
smallest displacement that can be determined with reasonable reliability"
dissociation: The breakdown of a substance into two or
more constituents.t
distal: In a manipulative or interrogating system, of or pertaining to the end opposite from the eyepiece and farthest from the person using the system. Objective; tip.8
distance amplitude correction (DAC): Compensation of
gain as a function of time for difference in amplitude of
reflections from equal reflectors at different sound
travel distances. Refers also to compensation by electronic means such as swept gain, time corrected gain,
time variable gain and sensitivity time controP,12
NONDESTRUCTIVE TESTING GLOSSARY I
divergence: A term used to describe the spreading of
ductility: The ability of a material to deform plastical
ultrasonic waves beyond the near field. It is a function
without fracturing, being measured by elongation or
of transducer diameter and wavelength in the
:eductio? of area in ate.n.isile test, by height of cuppinru,;.',.:.•
medium.'
III an Erichsen test or by other means.2;",~
domain: A saturated macroscopic substructure in ferrodwell time: The total time that the penetrant or emulsifier
magnetic materials where the elementary particles
is in contact with the test surface, including the
(electron spins) are aligned in one direction by interrequired for application and the drain time. 2
atomic forces. A saturated permanent magnet. 6.l O
dynamic creep: Creep that occurs under conditions
dose: The amount of ionizing radiation energy absorbed"
fluctuating load or fluctuating temperature.f
per unit mass of irradiated material at a specific loca- " od.yn:;j,~ic r:mge: The ratio ~f ~aXi:num to minimum refJe(.·.·•.-•. •.~•.
tion, such as part of the human body. Measured in rems
tive 'are~s that can be distinguished on the cathode' ra.~
and rads. ll
tube'at a constant gain setting.'·23.M
dose rate: The radiation dose delivered per unit time and
measured, for instance, in rems per hour. See also
E
dose. 11
dosimeter: A device that measures radiation dose, such as a
echo: A signal indicating reflected acoustic energy.'_.
film badge or ionization chamber.lECT: Eddy current testing.
1
eddy current: An electrical current induced in a conducte!
double crystal method: A method of ultrasonic testing
that uses two transducers, one transmitting and the
by a time varying magnetic field. 4
7
10
other receiving. .
.
eddy current testing: A nondestructive testing method
drag: The bottom section of a flask, mold or pattern. 3
which eddy current flow is induced in the test objec . • •.
Changes in the flow caused by variations in the object
dragout: The carryout or loss of penetrant materials as a
are reflected into a nearby coil, coils, Hall effect device
result of their adherence to the test pieces."
drain time: That portion of the dwell time during which
or .other ~agnetic f1u~ sensor forsu?sequent analysis 1.1··.
suitable instrumentation and techmques. 4•I3
;
the excess penetrant, emulsifier, detergent remover or
developer drains off the test piece.?
edge or end effect: In electromagnetic testing, the disturdrop: A discontinuity in a casting due to a portion of the
banceorof. th.e magne.. tic field and eddy cUrrents due. tl.l.·•.
sand dropping from the cope or overhanging section of
the proximity of an abrupt change in geometry. The ...
effect generally results in the masking of discontinuities
the mold.3
drop out: The falling away of green sand from the walls of a
1
within the affected region. 4 ,13
mold cavity when the mold is closed.'
effe~tive dep~ .of penetration: In elec~romagnetictest,
dross: The scum that forms on the surface of molten metals
mg, the mmrmum depth beyond which a test system'
largely because of Oxidation but sometimes because of
can no longer practically detect a further increase in
object thickness. If the minimum thickness for the fre
the rising of impurities to the surface. 3
quency used is not exceeded or the object thickness
dry bulb temperature: Alternate term for ambient or atnot rigidly controlled, the test may be influenced by the
mospheric temperature. 1
object thickness.P Depending on the criteria, this min "
dry powder: Finely divided ferromagnetic particles select. ed and prepared for magnetic particle testing. 6.10
imum thickness is three to seven times the skin depth.<;
effective penetration: In ultrasonic testing, the maximum
dry technique: A magnetic particle testing technique in
which the ferromagnetic particles are applied in a dry
~:fe~teid>~O material at which discontinuities can be) \
powder form. 6,16
effective throat: In welding, the weld throat including th6. J
drying oven: An oven used for drying rinse water from test
pieces.r
amount of weld penetration but ignoring excess metal
between the theoretical face and the actual face.8
drying time: The time allotted for a rinsed or cleaned test
piece to dry.Z
elastic constants: Modulus of elasticity, either in tension,
compression or shear and Poisson's ratio. 2
dual response penetrant: A penetrant that produces discontinuity indications that can be seen under either
elastic deformation: Temporary change in shape under a
load. The material returns to its original size and shape I
ultraviolet light or visible light. 2
after the load is removed. Elastic deformation is the .1
dual transducer: A single transducer containing two piezostate in which most metal components are used in serelectric elements, one for transmitting and one for
vice.8
receiving.'·12
ductile crack propagation: Slow crack propagation that is
elastic limit: The maximum stress to which a material
accompanied by noticeable plastic deformation and
be subjected without any permanent strain remaining
on complete release of stress."
requires energy to be supplied from outside the body.2
I.'.,.;.i.1
....
il·.
•
Q
I NONDESTRUCTIVE TESTING OVERVIEW
·~.~!rlasticity: The
ability of a material to resume its former
shape after deformation.f
electric arc welding: Joining of metals by heating with
111 electric arc. Also called arc welding. 8
<~lectric field: A vector field of electric field strength or of
electric flux density.4,14
r
1.• . •·.
1ectri.c.al c.:e~~er: ~h.e. ce~ter e.st~blished by.. the elec.tro• .• • •.
magnetic held distribution within a test cOIL A constant
intensity signal, irrespective of the circumferential position of a discontinuity, is indicative of electrical centering. The electrical center may be different from the
physical center of the test coiL4.I3
electrical noise: Extraneous signals caused by externally
radiated signals or electrical interferences within an
ultrasonic instrument.l? A component of background
noise.'
lectr.ochemical corrosion: Corr?sion that o~curs when
.
current flows between cathodic and anodic areas on
metallic surfaces."
-l·.
..81Ie.ctrod
. . . e: A cond.~ctor ~y which a current p. asses into.. or
. out of a test object. 6.1."
'" ectromagnet: A soft iron core surrounded by a coil of
wire that temporarily becomes a rnagnet when an elec.\ tric current flows through the wire. 6.16
Jectromagnetic acoustic transducer: An electromagnetic device using Lorentz forces and magnetostriction
in conductive and ferromag-netic materials to generate
and receive acoustic signals for ultrasonic nondestructive tests.'
electromagnetic testing (ET): A nondestructive test
method for materials, including magnetic materials,
.' . that uses electromagnetic energy, both alternating and
direct current, to yield information regarding the qualitv and characteristics of the tested material. 4.13
.• eetrostatic spraying: A technique of spraying wherein
the material being sprayed is given a high electrical
charge (potential) while the test piece is grounded. 2
kment: A chemical substance that cannot be divided into
J simpler substances by chemical means. Examples are
hydrogen, lead and uranium.f
hngation: In tensile testing, the increase in the gage
length, measured after fracture of the object within the
gage length, usually expressed as a percentage of the
I original gage length. 2
j\1AT: See electromagnetic acoustic transducer:
embrittlement: Reduction in the normal ductility of a
I metal due to a physical or chemical change. 2
'
~issivity: Variable ratio of the total energy radiated by a
, given surface at a given temperature to the total energy
radiated by a blackbody at the same temperature. Surface phenomenon depending on the surface condition
and composition. Smooth materials have lower emissivities than rough or corroded materials.?
j
1
r
emulsification time: In liquid penetrant testing, the
period of time that an emulsifier is permitted to cornbine with penetrant before removal. Also called emulsi-
fier dwell time.2
emulsifier: A liquid that combines with an oil based penetrant to make it water washable.P
emulsion: A dispersion of fine droplets of one liquid in
another that can be stabilized bv the addition of an
emulsifier.''
'
encircling coil: In electromagnetic testing, a coil or coil
assembly that surrounds the test object. Such coils are
also called annular, circumferential or feed-through
coils. 4•1:3 See coil technique.
endoscope: Device for viewing the interior of objects.
From the Greek words for inside view, the term endoscope is used mainly for medical instruments. Nearly
every medical endoscope has an integral light source;
many incorporate surgical tweezers or other devices.
Compare borescope. S
equilibrium diagram: A phase diagram showing. the
phases present at equilibrium in a material system."
equivalent 20/20 near vision acuity: Vision acuity with
. remote viewing or other nondirect viewing that approximates 20/20 direct viewing closely enough to be considered the same for visual testing purposes.f
equivalent sphere illumination: Level of perfectly diffuse (spherical) illuminance that makes the visual task
as photometrically visible within a comparison test
sphere as it is in the real lighting environment.f
erosion: (1) Loss of material or degra.dation of surface quality
through friction or abrasion from moving fluids, made
worse bv solid particles in those fluids or bv cavitation in
the moving fluid. See wear: (2) In image processing, condition of a binary image where the pixel in the output
image is a 1 if each of its eight neighbors is a 1 in the
input image. See also closing, dilation and opening. 8
erosion-corrosion: Simultaneous occurrence of erosion
and corrosion."
ET: Electromagnetictesting.
etch cracks: Shallow cracks in hardened steel containing
high residual surface stresses produced by etching in an
acid. 2 •s.Is
etching: A cleaning process for the controlled removal of
surface material by chemical agents before liquid penetrant application.s Subjecting the surface of a metal to
preferential chemical or electrolytic attack in order to
reveal structural details. 2
eutectic alloy: The composition in a binary alloy system
that melts at a minimum temperature. More than one
eutectic composition may occur in a given alloy
svstem.f
eute~tic liquid: A liquid having a proportion of metals such
that two or more solid phases form at the same temperature during cooling. B
NONDESTRUCTIVE TESTING GLOSSARY I
eutectic point: Temperature and proportion of metals at
false brinelling: Fretting wear indentations.
brinelling. 8
which two or more phases of a eutectic liquid form.
Compare eutectoidl:
eutectoid: Similar to eutectic but in a solid system during
as originating from a discontinuity but _which actu;;(jl';'
originates where no discontinuity exists.' Distinct fr&1!
nonrelevant indication.f Compare defect. s
y An obsolet.e
.
. , ~orm. er--.l--.
y den.oti·ncr
..
I::> a
.
;
famil«-:
.term
co.;
. mpl'
.:•.·.• c.•·••·.
series of materials from one manufacturer necessary''!
perform a specific process of penetrant testing. 2
cooling."
evaluation: Process of determining the magnitude and significance of a discontinuity after the indication has been
interpreted as relevant. Evaluation determines if the
test object should be rejected, repaired or accepted.
See indication and interpretation. Z•6.'
evanescent wave: A disappearing wave.'
event: A micro displacement giving rise to transient elastic
waves. See acoustic emission event. 5
event counting: A measurement of the number of acoustic
emission events. Because an event can produce more
than one burst, this term is used in its strictest sense
only when conditions allow the number of events to be
related to the number of bursts.P
event rate: The number of events detected in a specified
unit of time. Term is restricted in the same way as event
counting. 5
examination: The process of testing materials, interpreting
and evaluating test indications to determine if the test
object meets specified acceptance criteria.f
examination medium: A powder or suspension of magnetic particles applied to a magnetized test surface to
determine the presence or absence of surface or
slightly subsurface discontinuities.v-"
excitation coil: Coil that carries the excitation current. Also
called primary coil or winding. See detector coil. 4
exfoliation: Corrosion that progresses approximately parallel to the outer surface of the metal, causing layers of
the metal to be elevated bv the formation of corrosion
product.f
expanded sweep: A short duration horizontal sweep positioned to provide close examination of a particular signal or material volume.'
external discontinuities: Discontinuities on the outside or
exposed surface of a test object."
eye sensitivity curve: Graphic expression of vision sensitivity characteristics of the human eye. In the case of a
physical photometer, the curve should be equivalent to
the standard observer. The required match is typically
achieved by adding filters between the sensitive elements of the meter and the light source."
J
F
facing: Any material applied in a wet or dry condition to the
face of a mold or core to improve the surface of the
ti 3
cas.ng.-
.
false indication: A test indication that could be interprel~):::(:
t
...
·.:
....
·
• .;t".
~one ?eYO~d. the. ne~r fi.e.ld l.·n fro0.. nt of ~. •.'•[. .• '.• .•'.
tranglpcer 10 which Signal amplitude decreases mosstonically in proportion to distance from the transduce .
Also talled the Fraunhofer zone.'
far vision: Vision of objects at a distance, generally
arm's length. Compare near vision. S
farsightedness: Vision acuity functionally adequate for view-
far.a.· eId..: T.he
'-. '.13 ~enr. . l.• '. L
ing. object.s at a cli.' st~nce,. gen.-e.rally.bey,ond. arm.
Also called hyperopza. Compare nearszghtedness. 8
i
fatigue fracture: The progressive fracture of a material that
begins at a discontinuity and increases under repealed
cycles of stress. The phenomenon leading to fraet • •
under repeated or fluctuating stresses haVing a ffi":mum value less than the tensile strength of the material.r
feature extraction: From an enhanced image, derivaCJ1
of some feature values, usually parameters for disl~­
guishing objects in the image."
feed-through coil: See enCircling, coil.
feeder: A reservoir of molten metal connected to, but nc
part of, the casting and designed to remain liquid
the casting is solidifying. It is located so that it will
liquid metal to the larger portions of the casting that
the last to solidify. Sprues, gates, risers and runner-s
quently function in this manner.'
felicity effect: The appearance of significant acoustic
sion at a stress level below the previous maximum
plied. 5
feliC.i.ty. ra.tio: The meas.ur~m
...en
..t of th. e fel.icity effect.
R~JE"'
.• '.· 0_
between (1) the applied load or pressure at wh L
acoustic emission reappears during the next apphcatsi .
of loading and (2) previous maximum applied load."
ferrite: (1) Any of several magnetic substances that
essentiallvof an iron oxide combined with one or
metals (~anganese, nickel or zinc) ha.ving high magnetic
permeability and high electrical resistivity. (25 (2) SCi1jp
.solution o! one or n;ore other .elements i~ alpha ~ron'.iJI.
ferromagnetic material; Matenal such as Iron, nickel or
cobalt whose relative permeability is considera91~
greater than unity and depends on the magnetiz:'
force. 4 .l 4 Materials that are most strongly affected.i/·
magnetism are called ferromagnetic. 2
fiber optic borescope: See borescope, fiber optic.
fiber optics: The technology of light transmission
crystalline fibers such as plastic, glass or quartz. S
fiberscope: Jargon for fiber optic borescope.v
532 / NONDESTRUCTIVE TESTING OVERVIEW
field: In video technology, one of two video picture components that together make a frame. Each picture is
divided into two parts called fields because frame at
the rate of thirty frames per second in a standard video
output would otherwise produce a flicker discernible to
the eye. Each field contains one half of the total picture
elements. Two fields are required to produce one complete picture or frame so the field frequency is sixty
fields per second and the frame frequency is thirty
frames per second. S
'jIeld ang~e: ~he included angle ?etwee~ those poin.ts.on
opposite SIdes of the beam axis at which the luminous
intensity from a theatncal luminaire is 10 percent of the
maximum value. This angle may be determined from an
illuminance curve or may be approximated by use of an
incident light meter. S.~O
iield flow technique: See magnetic flow technique. 6
field. of view: The range or area where things can be seen
through an imaging system, lens or aperture. Compare
depth offield. S
1eld o.f vision: The r~nge or area :-vh~re ~hings.can~e perceived organoleptically at a pomt m time, assummg the
eye to be immobile."
"tUI factor: For encircling coil electromagnetic testing, the
J
ratio of the cross sectional area of the test object to the
effective cross sectional core area of the primary encir~l..
cling coil (outside diameter of coil form, not inside
I diameter that is adjacent to the object) .4,6,13.15 For Internal probe electromagnetic testing, the ratio of the
effective cross sectional area of the primary internal
probe coil to the cross sectional area of the tube interior.4.13
fill factor effect: The effect of fill factor on coupling
I between coil and test object. Se.e. c.oupling coefficient. 4
.Jilled crack: A cracklike discontinuity, open to the surface,
but filled with some foreign material, such as oxide,
grease, etc., that tends to prevent penetrants from
. entering.~
tinet weld: Weld at the comer of two metal pieces.s
a
rF badge: A package of photographic film worn as a
I badge by radiography personnel (and by workers in the
•.
nuclear industry) to measure exposure to ionizing radiation. Absorbed dose can be calculated by degree of
I film darkening caused by irradiation. II
JIm holder: A light tight carrier for films and screens.l!
film speed: Relative exposure required to attain a specified
) densitv.'!
~ter: (1).1 A network that passes electromagnetic wave
energy over a described range of frequencies and attenuates energy at all other frequencies. 4 •13 (2) A processing component or function that excludes a selected kind
of signal or part of a signal.8
f~terlng: See low pass filtering.
fine crack: A discontinuity in a solid material witha very
fine opening to the surface, but possessing length and
depth greater than the width of this opening. Usually
the depth is many times the \vidth.2
Unite element analysis: A numerical technique for the
analysis of a continuous system whereby that system is
decomposed into a collection of finite sized elements."
fit up: To secure one or more joint members with special
external fixturing to prevent movement during welding.B.19
flakes: Short discontinuous internal fissures in ferrous metals attributed to stresses produced by localized transfermation and/or decreased solubility of hydrogen during
cooling usually after hot working, On a fractured surface, flakes appear as bright silvery areas; on an etched
surface they appear as short, discontinuous cracks.B.l 9
Also called shatter cracks and snowflakes. ~
flash magnetization: Magnetization by a current flow of
brief duration. See capacitor discharge technique. 6,16
flash point: The lowest temperature at which vapors above
a volatile, combustible substance ignite in air when
exposed to flame.6.l6
flask: A metal or wood frame for making and holding a sand
mold. The upper part is called the cope and the lower
part is called the drag.3
flat bottom hole: A type of reflector commonly used in
reference standards. The end (bottom) surface of the
hole is the reflector,'
flaw: A rejectable anomalyor unintentional discontinuity.
See also defect and discontinuity. :2
flaw inversion: A method for measuring some dimensions
of a discontinuity by the application of a mathematical
algorithm to the discontinuity signal.4
flaw location scale: A specially graduated ruler that can be
attached to an angle beam transducer to relate the position of an indication on the cathode ray tube screen to
the actual location of a discontinuity within the test
object.'
fluidity: The abilityof molten metal to flow readily. Typically
measured by the length of a standard spiral casting.?
fluorescence: The emission of visible light from a material
in response to ultraviolet or Xvradiation. Formerly
called cold light. S
fluorescent penetrant: A highly penetrating liquid used
in the performance of liquid penetrant testing and
characterized bv its ability to fluoresce under ultravio•
let light.:2
fluorescent magnetic particle testing: The process using
finely divided ferromagnetic particles that fluoresce
when exposed to ultraviolet light (320 to 400 nm).6.l.
fluorescent penetrant testing: Technique of liquid penetrant testing that uses fluorescent penetrant.
flux density: See magnetic flux density.
.I
NONDESTRUCTIVE TESTING GLOSSARY I
f"re;,fel=:':~:';.:,:u~rm;',\'d~n:,i~~:':~
flux indicator: A small device, generally a metal strip or
disk, containing artificial discontinuities. Used to determine when correct magnetizing conditions and/or magg.
in to v.a.. ri.ation.s... l.·n. th.'.',ickness o. f material or to. caYi~•I. • .•*~•1.c. •..s•~ .l.i'
netic field direction have been achieved."
May be sand, slag, made or dross metal or any mater!).r
flux leakage: A local distortion of normal magnetic flux
included in the material being examined. 3
;::
patterns in a magnetized test object. Can be caused by
forging crack: Discontinuity formed during mechanical
discontinuities in the test object."
shaping of metal. S
flux leakage field: The magnetic field that leaves or enters
foundry: An establishment or building where metal
the surface of an object. 6.l 6
ings are produced.P
flux leakage method: A method for the detection and anal- .... fov~ .:centralis: Region of sharpest vision in the retim,
ysis of a surface discontinuity or near-surface discontiwhe.(~_the layer of blood ~essels, ~erve fibers. and ~(.i~;ls
nuity using the flux that leaves a magnetically saturated,
above, the rods and cones 1S far thinner than in penpnor nearly saturated, test object at a dlscontinuityv"
eral regions.s .
flux lines: See lines afforce.
foveal vision: See photopic v i s i o n . · l
flux method: See lumen method.
fractography: Descriptive treatment of fracture, especi1;"
flux meter: An electronic device for measuring magnetic
in metals, with specific reference to photographs of the
flux.6 See also gauss meter.
fracture surface. Macrofractography involves
focal zone: The distance before and after the focal point in
tographs at low magnification, microfractographyJt
high magnification.t
.,
which the intensity differs a specified amount (usually 6
dB) from the focal intensity, Also called depth offield or
fracture: A break, rupture or crack large enough to cauJ'
depth offocus,7
full or partial partition of a casting. 2,3
•
focus: Position of a viewed object and a lens system relative
frame: A complete raster scan projected on a video scree} ..
to one another to offer a distinct image of the object as
There are thirty frames per second in a standard video
seen through the lens system. See accommodation and
o~tput.. A frame may be comprised of two,- .fie14s, e~~.'P
.:
depth offield. S
displaying part of the total frame. See also field. S
.iI
focus, principal plane of: The single plane actually in
Fraunhofer zone: See far field.
focus in a photographic scene."
free carbon: The part of the total carbon in steel or
focused beam: A sound beam that converges to a cross seciron that is present in the elemental form as graphite
tion smaller than that generated by a flat transducer.'
temper carbon.'
focused transducer: A transducer that produces a focused
frequency: The number of complete wave cycles passingll
sound beam."
given p~int per second or the number of vibrations l . r
focusing, automatic: (1) Feature of camera, usually
'..
second. Measured in hertz (Hz).
incorporating a range finder, whereby the lens system
frequency, fundamental: In resonance testing, the freadjusts to focus on an object in part of the field of
~~~~~e~~ :~~~~~~,iavelength is twice the thicknr
view. (2) Metaphorical attribute of a borescopic
instrument's depth of field (the range of distance in
frequency, pulse repetition: The number of pulses per
second, in hertz (Hz).'
focus). The depth of field is so great in the case of
video borescopes that focusing is unnecessary for most
frequency, test: The nominal ultrasonic wave test f
applications. S
queney used in a test. 7 .12
focusing, primary: Focusing of an image by the lens onto a
Fresnel zone: See nearfteld. Also called Fresnelfteld. 7
fretting: Action that results in surface damage, especiallj p
fiber optic bundle at the tip of a probe,"
a corrosive environment, when there is low amplitu ~
focusing, secondary: Focusing at the eyepiece of a
motion between solid surfaces in contact under presborescope or other optical instrument, specifically the
sure. Also calledfretting corrosion.2
manual refocusing needed when the viewing distance
changes."
fretting corrosion: See corrosion? fretting.
foil: Metal in sheet form less than 0.15 mm (6 x 10-3 in.)
fretting wear: See wear,fretting.
thick 2
frictiOIi oxidation: See wear, fretting.
footcandle: Former unit of measure for illumination,
front surface: The first surface of a test object enCOI L
equivalent to one lumen evenly distributed over a
tered by the incident ultrasonic beam. See inteiface.· J
square foot or to a surface illumination at a distance of
full-wave direct current: A single-phase or three-phase
one foot from a point of one candela. Abbreviated ftc or
alternating current rectified to produce direct curre .• .~
fc. See also lux.S
characteristics of penetration and flow.6
\ ;I
footlambert: Former unit of luminance. Measured in the
furring: Buildup or bristling of magnetic particles resulting
SI system by candela per square meter."
from excessive magnetization of the test object,6.16
Y
pr,-
l.
I
I
NONDESTRUCTIVE TESTING OVERVIEW
G
m:ga2:e pressure: Pressure above (or below if measured from
gage zero) atmospheric pressure at the measurement
location.'
taAA~~:/"" metal $Upports that
sand in the
reinforce
galling: A type of adhesive wear more gross than frettmz,"
".,galvanic series: List of metals, alloys and graphite (a n~nmetal) i~ s~qu~nce wi.t.h the.most an.odic (easiest cor.
roded) In liquids at one end and the most cathodic
(least easily corroded) at the other end.s
~~amma iron: Iron with face centered cubic structure
I formed by slow cooling of delta ferrite. This characteristic lattice structure is stable between 906°C (1,663 OF)
...
and 1,390 °C (2,535 OF). Also called austenite. s
~amm~ ray~: ~igh ~nergy, short wavelength. electromagnetic radiation emitted by a nucleus. Energies of gamma
rays are usually between 0.01 and 10 MeV. X-rays also
' '1.
occur in this energy range but are of non-nuclear origin.
I Gamma radiation usually accompanies alpha and beta
emissions and always accompanies fission. Gamma rays
. .]
are v~ry p~netratin.g and are best at:tenuated by dense
materials like lead and depleted uranium. II
gas holes; Holes created by a gas evolving from molten
metal.- Appear as round or elongated, smooth edged
.\
dark spots, occurring individually, in clusters or distributed throughout a casting. 3
gas porosity: Gas pockets or voids in metal. Refers to
porous sections in metal that appear as round or elongated dark spots corresponding- to minute voids usuallv
distributed through the entire casting.' Spherical or
elongated internal cavities caused by evolution of dissolved gasses from molten metal or slag trapped durinz
cooling and solidification of castings or fusion welds. 2 0
~as tungsten arc welding (CTAW): Inert gas shielded arc
welding using a tungsten electrode. Also called tung..1.........
.1
sten inert gas (TIG) welding. s
gasket seal: Resilient ring, usually virgin polytetrafluoroethylene (PTFE), in a piping or tubing connection.
Compare interference sealing thread and metal-tometal seal. s
,ate.: (I! In ~traso~ic testing, an electronic device for mon1
Itonng signals III a selected segment of the trace on an
J
A-scan display. (2) The interval along the baseline that
is monitored." (3) In casting, the channel through which
molten metal enters a mold cavity. Sometimes called
ingate. 3
gated pattern: A pattern designed to include gating in the
J
1
mold.'
~auss:
A customary or cgs unit of flux density or magnetic
induction. See tesla.s
gauss meter: A magnetometer that registers field strength
in gauss (or Tesla)."
general examination: A test or examination of a person's
knowledge, typically (in the case of nondestructive testing personnel qualification) a written test on the basic
principles of a nondestructive testing method and general knowledge of basic equipment used in the method.
(According to ASNT's guidelines, the general examination should not address knowledge of specific equipment, codes, standards and procedures pertaining to a
particular application.) Compare practical examination
and specific examination. S
geometric moire techniques: Moire techniques that can
be explained by geometric optics, mainly by the
mechanical obstruction of light or the scalar addition of
light,9
geometrical optics: The mathematical study of how light
rays are reflected and refracted and practical techniques based on such understanding, including the
transmission of images by lenses and mirrors. Also
called lens optics. S
ghost: An indication arising from a combination of pulse
repetition freguency and time base frequency.w See
wrap around. "I
glare: Excessive brightness (or brightness varying by more
than 10:1 within the field of view) which interferes with
clear vision, critical observation and judgment. 8
glare, blinding: Glare so intense that for an appreciable
length of time after it has been removed, no object can
be seen. 8.20
glare, direct: Glare resulting from high luminances or
insufficiently shielded light sources in the field of
view.s.2o
glare, reflected: Glare resulting from specular reflections
of high luminances in polished or glossy surfaces in the
field ofview. s.2o
glossmeter: Reflectometer used to measure specular
reflectance.V"
gooseneck: The pressure vessel or metal injection pump in
.
an air injection casting machine."
gouge: Surface indentation caused by forceful abrasion or
impact or flame cutting. Also called nick. Compare tool
mark:"
.
grain boundary: Interface that forms between grains of
solidifVing metal as the random oriented crvstal lattices
"
meet. "See grain. I)
grain refiner: 'Any material, usually a metal from a special
group, added to a liquid metal or alloy to produce a
finer grain in the hardened metal,"
grain size: Size of the crystals in metal. When compared
with a standard, usually referred to as being fine,
medium Or coarse.f
NONDESTRUCTJVE TESTJNG GLOSSARY I
graininess: A film characteristic that consists of the group-
halide: A compound of two or more elements, One
ing or dumping together of the countless small silver
grains into relatively large masses visible to the naked
eye or with slight magnification. 11
grains: (I) Solid particle or crystal of metal, As molten
metal solidifies grains grow and lattices intersect, forming irregular grain boundaries.f (2) Individual crystals
that make up the crystalline structure of metal.f
grass: See background noise.
grating: A grid superimposed on an optical test surface to
measure displacement or deformation. See also reference grating. 9
gray: SI unit for measurement of absorbed radiation dose,
absorbed by matter at a particular location and
expressed in joules per kilogram (}.kg~I). Replaces the
rad.
gray level: Integer number representing the brightness or
darkness of a pixel or, as a composite value, of an image
comprised of pixels. s
graybody: Radiator whose spectral emissivity is uniform for
all wavelengths but not 1.0. See blackbody.s
green core: A sand casting core that has not been baked."
green rot: Form of attack due to simultaneous carburization and oxidation of stainless heating elements common to nickel chromium and nickel chromium iron
allovs, especially in furnace environments,"
green s~nd: Core ;and intended for use in a damp state.'
grid: In moire and grid nondestructive testing, cross hatch
pattern of two sets of parallel lines, one set of lines
being perpendicular to the other; the lines in each set
are parallel to each other and spaced at fixed intervals.
The term grid also refers to the physical or real cross
line grating. 9
grinding cracks: Shallow cracks formed in the surface of
relatively hard materials because of excessive grinding
heat or the high sensitivity of the material.f Grinding
cracks typically are 90 degrees to the direction of grind-
is a halogen. 1
haHtation: Rings of light visible around a spot on a
screen where an electron scanning beam is held. 8
Hall detector: A semiconductor element that produces
ina
8.19
-
b'
gross porosity: In weld metal or in a casting, pores, gas
holes or globular voids that are larger. and in greater
number than obtained in good practice. 2.3
group velocity: The rate at which the envelope of an ultrasonic pulse (many frequencies) propagates through the
medium.'
growth: The expansion of a casting because of aging. 3
H
Hadfield's steel: An austenitic manganese specialty steel
that is easily work hardened."
half-wave direct current: A single-phase alternating current half-wave rectified to produce a pulsating unidirectional field. Also called half-wave current. 6 •16
ii
. . . .•
•
output
electromotive
force prop.
.omo.nal
t.o the
prod4 ,!
of
the magnetic
field intensity
and
a biasing
current.
Hall effect: A potential difference developed across aeon'..
/0.,
ductor at right angles to the direction of both the ma;~_ne~:.field and the electric current. Produced ~her.i .
cUI;'~~fldlows along a rectangular conductor subject> •.
to a transverse magnetic field. 6 ,15
halogen: Any of the nonmetallic elements - fluorit}
chlorine, bromine, and iodine - or any gaseous chen}}
cal component containing one or more of these elements.
halogen leak detector: A leak detector that responds
halogen containing tracer gases. Normally not very sensitive to the elemental halog.en gases, but are very gO.(,)Qi•.when they are used with a gas that contains haloge: •
Also called a halogen sensitive leak detector or a halia
leak detector. 1
halogen sniffer test: A pressure leak test in which
tl
leakage of a component, pressurized with a halog~._
rich mixture, is detected by scanning over the test
object boundary surface with a probe connected t(~
halogen leak detector. Halogen gas is pulled from tJ
leak through the probe inlet to the sensing element to
f::~e~ti~~~~~~~~1ible signal
on the indicator of thl
halogen standard leak: A standard leak in which the cofitained gas is a halogen tracer gas compound. 1
-: ,
har~~s~~ ~~~~~:~C;n~~::~~e;~~l:~~~:;:~~~~or~f::t~
stiffness or temper or to resistance to scratching, abr;:tsion or cutting.:?:
harmonic: A vibration frequency that is an integral muidple of the fundamental frequency.i.lO
1
harmonic a~alyzer: A mechanical d~vice for me~uri'~
the amplitude and phase of the various harmonic c01~.;!.
ponents of a periodic function from its graph. 4 ,14
harmonic distortion: Nonlinear distortion characteriz'ia
by the appearance in the output of harmonics oth.t
than the fundamental component when the input wave
is sinusoldal.vP
hash: See background noise.
head shot: Producing circular magnetization by passing
current directly through the test object. Commo!!'t
done while. holding the object between the headstoi ,·f
and tailstock ofa wet horizontal magnetic particle test:'
ing system."
536 I NONDESTRUCTIVE TESTING OVERVIEW
~i~heading: Upsetting wire, rod or bar stock in dies to form
::1
parts having some of the cross sectional area larger than
the original. Examples are bolts, rivets and screws. 8J 9
f.•.~•). •'.,~.' head.s: Th.e clamping contacts on stationary magnetic parti:.1 de systems. 6•10
'heat: The energy associated with the random and chaotic
motions of the atomic particles from which matter is
composed. All materials (hot or cold) contain heat and
radiate infrared energy. The unit for measuring heat is
the joule (J), equal to about 0.24 calorie (cal) or
9.481 X 10-4 British thermal units. (BTUs). Compare
infrared radiation and temperature. 9
heat affected zone (HAZ): Base metal not melted during
"l'. braZI._·n g,. ~utting. or ,,;elding, but whose microst.r;tcture
and physical properties were altered by the heat.'
•
.eat checking: Surface cracking caused when metal
rapidly heated (or cooled and heated repeatedly) is prevented from expanding freely by colder metal below
the surface. Friction may produce the heat. Sometimes
called thermal fatigue. s
lteat treatment: Heating and cooling a metal or alloy in
I such a way as to obtain desired conditions or properties.
Heating for the sole purpose of working is excluded
! from the meaning of this definition. 2.3
teat wave: Thermally produced variation in flue gas density that distorts images of objects in a fireboxf
··.·1-.e.Hum., leak.'
de.,tect..o r: A leak detecto.r that responds to
helium tracer gas. 1
r elium mass spectrometer leak detector: Mass spectrometer constructed to be peaked for response to
helium gas.
ertz: The ~nit of frequency equivalent to one cycle per
second. 4 . 1 • 1O.14
'pgh temperature penetrant: A penetrant material speJ cifically designed for use on high temperature surfaces
... where conventional penetrant would be unsatisfactory?
~jndered contraction: Contraction where the geometry
will not permit a casting to contract in certain regions in
I
keeping with the coefficient of expansion of the metal
being cast. 3
Ie.s: Any void remaini?g in an object as a result of
· • Improper manufactunng processing. Often called gas
holes, cavities or air locks. 2
· pmogenizing: Holding at high temperature to eliminate
! or decrease chemical segregation by diffusion.?
hood test: A quantitative leak test in which a test object
under vacuum test is enclosed by a hood filled with
tracer gas so as to subject all parts of the test object to
examination for leakage at one time, A form of dynamic
leak testing in which the entire enclosure or a large portion of its external surface is exposed to the tracer gas
while the interior is connected to a leak detector with
the objective of determining the existence of leakage.'
.
1
I
'0,
horizontal linearity: In ultrasonic testing, a measure of
the proportionality between the positions of the indications appearing on the horizontal trace and the positions of their sources.'
horn gate: A curved gate shaped like a hom and arranged
to permit entry of molten metal at the bottorn of casting
cavity.3
.
horseshoe coil: A probe coil in which the ferrite core of the
coil is horseshoe shaped. Also called' a V coil or Uroore
coil. 4
horseshoe magnet: A bar magnet bent into the shape of a
horseshoe so that the two poles are adjacent. Usually
the term applies to a permanent magnet. 6.10
hot cracks: Ragged dark lines of variable width and
numerous branches. They have no definite line of continuity and may exist in groups. They may originate
internally or at the surface." Cracks occurring in hot
solid metals, caused by stresses of thermal expansion
or contraction and originating either internally or at
the surface. 2
hot thermionic ionization gage: Positive ion current
flowing frorn a tungsten or thorium coated filament to
a cylindrical grid collector is proportional to gas density over the absolute pressure range below 100 rnPa
(10-3 torr).
.
hot spot: The point of retarded solidification caused by an
increased mass of metal at the juncture of two sections.
It frequently results in shrinkage and inferior mechanical properties at this location,2.3
hot tear: A fracture formed in a metal during solidification
because of hindered contraction. Surface cracks on
castings ~roduced by contraction of the metal during
cooling. 2 .· Hot tears often occur where areas of different thickness adjoin. s
hot working: Deforming metal plastically at temperature
and rate such that strain hardening does not occur. Low
temperature limit is recrystallization temperatnre.f
hue: Characteristic of light at a particular bandwidth that
gives a color its name."
hundred percent testing: See one hundred percent testing.
hydrogen embrlttlement: A condition of low ductility in
metals resulting from the absorption of hydrogen.'2
hydrophilic emulsifier or remover: Water base materials
used for excess surface penetrant removal.?
hyperthermia: Heating so excessive that it can damage or
kill plant Or animal cells. 8
hysteresis: (1) The lagging of the magnetic effect when the
magnetizing force acting on a ferromagnetic body is
changed. (2) The phenomenon exhibited by a magnetic
system wherein its state is influenced by its previous
history"
-
NONDESTRUCTIVE TESTING GLOSSARY I
hysteresis loop: A curve showing flux density B plotted as a
function of magnetizing force H as magnetizing force is
increased to the saturation point in both negative and
positive directions sequentially. The curve forms a characteristic S shaped loop. Intercepts of the loop with the
B~H axis and points of minimum and maximum magnetizing force define important magnetic characteristics
of a material. 6.10
IACS; The International Annealed Copper Standard. A
conductivity measurement system in which the conductivity of annealed, unalloyed copper is arbitrarily rated
at 100 percent and the conductivities of other materials
are expressed as percentages of this standard." The
% lACS is equivalent to 172 divided by the material
resistivity in microohm centimeters."
icicles: A coalescence of metal protruding beyond the root
of the weld. Sometimes called bum through. 2
ID .coil; A coil or coil assembly used for electromagnetic
testing by insertion into the test piece, as with an inside
probe for tubing. Also called inside coils or bobbin
coils. 4.13
ideal gas: Gas that obeys the general gas laws for ideal
gases. Also called peifect gai. 1
illuminance; The density of luminous flux on a surface.
Measured in the 51 system by lux.s
illuminate; Shed light on."
illumination: The act ofilluminating or state of being illuminated. See also illuminate. Compare illuminance. S,20
image; Visual representation of a test object or scene. S
image enhancement; Any of a variety of image processing
steps, used singly or in combination to improve the
detectability of objects in an image. s
image guide: Fiber bundle that carries the picture formed
by the objective lens at the distal end of a fiber optic
borescope back to the eyepiece."
image orthicon: Television tube that uses the photoernission method. Compare vidicon tube. S
image processing; Actions applied singly or in combination to an image, in particular the measurement and
alteration of image features by computer, Also called
picture processing. S
image quality indicator; Penetrameter,
image segmentation: Process in which the image is partitioned into regions, each homogeneous.f
immersion technique: The ultrasonic technique in which
the test object and the transducer are submerged in a
liquid (usually water) that acts as the coupling
medium. 12 The transducer is not usually in contact with
the test object,'
impedance; The total opposition that a circuit presents
the flow of an alternating current, specifically the
plex quotient of voltage divided by current.vP
impedance analysis: In electromagnetic testing, an <ltl<lh.'!'lli((j
ical method that consists of correlating changes in
amplitude, phase, quadrature components or all
th.ese, ~f a co~rlex t~st .Signal. voltag7 to ~e electra.•. •.'•.~.• .!•.
magnetic conditions within the test obJect,4,l.>
</~
impedance plane diagram: A graphical representation
~
(rea] part along the horizontal axis and imaginary p~
roongthe vertical axis) of the locus of points- indicatin<~
the ~afiations in the impedance of a test coil as a fun",,!
tion ofbasic test parameters.v'P
impedance, acoustic: A mathematical quantity used 1'1
computation of acoustic reflection and transmissio ..il
characteristics at boundaries. It is expressed as the
product of wave velocity and density.7.21
".
impre~ation; ~l) The treatment of porous castings with.}
sealmg medium to stop pressure leaks. (2) The prace",,,
of filling the pores of a sintered compact, usually with a
liquid such as a lubricant. (3) The process of moor"]
particles of a nonmetallic substance in a matrix of met ..1
powder, as in diamond impregnated tools.?
impurities; Elements or compounds whose presence in
material is unintentional.v''
in control: Within prescribed limits of process control.t
in-motion radiography; Technique in which either
object being radiographed or the source of radiation
in motion during the exposure.v'!
incandescence; The emission of visible radiation due to
thermal excitation."
incandescent: Emitting visible radiation as a result of hea
ing. s
inclusion._.; Fo 7.e.-. ign. p•. article.s..or imp.un.·ft.ies, u.suall~ oxides. '.1.
sulfides, silicates and such, that are retained m met
j
(welds or castings) during solidification or that are
23
formed by subsequent reaction of the solid metal. •
incomplete fusion: Fusion that is less than complete.
ure of weld metal to fuse completely with and bond
the base metal or preceding bead. 2
incomplete penetration: In welding, root penetration
is less than complete or failure of a root pass and a
ing pass to fuse with each other.' Also called lack
fusion. 2
incremental permeability: The ratio of the change
magnetic induction to the corresponding change
magnetizing force when the mean induction differs
from zero. 4 •14
.!
indication; A nondestructive testing discontinuity respon:.i
that requires interpretation to determine its relevance.
Compare defect, discontinuity and false indication. 8 ..'
indication, discontinuity; The visible evidence of a matt!
rial discontinuity. Subsequent interpretation is requireul
to determine the significance ofan indication.f
J•.!
53a / NONDESTRUCTIVE TESTING OVERVIEW
indication, falser An indication produced by something
other than a discontinuity. Can arise from improper test
prooedures.f
indication, nonrelevant: An indication due to misapplied
or improper testing. May also be an indication caused
by an actual discontinuity that does not affect the
usability of the object (a change of section, for
instancei.t
.
indication, relevant: An indication from a discontinuity
(as opposed to a nonrelevant indication) requiring evaluation by a qualified inspector, typically with reference
to an acceptance standard, by virtue of the discontinuity's size or location. S.22
induced current technique: See current induction technique.
induced magnetization: A magnetic field generated in an
O?~. . obj.ect when no direc.t electn.·cal con~act.is made. 6,l6 .
Imduction: The magnetism produced In a ferromagnetic
body by some outside magnetizing force. 6 ,10
~l induc~or: A de~ce co?sisting of one. or more a.ssociated
•
wmdings, with or without a magnetic core, for Introducing inductance into an electric circuit or matertal.v-"
dnert gas: Gas that does not readily combine with other
substances. Examples are helium, neon and argon.'
inert gas shielded arc welding: Joining of metals by heat~
ing them with an electric arc between the electroders)
and the work piece, using an inert gas to shield the electrode(s). See also gas tungsten arc welding. S
..infrared: Below red, referring to radiation of frequency
lower than the color red. See infrared radiation. 9
lnfrared and thermal testing: Nondestructive testing that
uses heat or infrared radiation as interrogating energy.
~frared cameras: Radiometer that collects infrared radial
tion to create an image. 9
infrared radiation: Radiant energy below the color red, of
wavelengths longer than 770 nm, between the visible
and microwave regions of the electromagnetic spectrum. S ,9 ..20
•·.
!
1
infrared
thermography:
Imaging. by infrared radiation.
.I
.
.
_.
See infrared radiation. Compare themwgraphy.9
ingate: See gate.
rherent discontinuities: Discontinuities that are pro1 duced in the material at the time it is formed (for example, during solidification from the molten state).2
'pherent fluorescence: Fluorescence that is an intrinsic
; characteristic of a material. 6 ,16
initial permeability: The slope of the induction curve at
zero magnetizing force as the test object is removed
from a demagnetizing condition (slope at the origin of
the B-H curve before hysteresis is observedl.vP
I
initial pulse: The electrical pulse applied to excite an ultrasonic transducer. The first indication on the screen if
the sweep is undelayed. Also called the main bang. May
also refer_to the acoustic pulse generated by the electrical pulse.'
inlet: The opening, flange, connection or coupling on a leak
detector or leak testing system through whlch tracer gas
may enter from a leak in a test object.'
inserted coil: See ID coil. Also called inside coil.4,13
insonification: Irradiation with sound. t
inspection medium: See examination medium.
inspection: See examination.
integrated leakage rate test (ILRT): The leakage test
performed for an entire system or component by pressurizing the system to the calculated peak containment
internal pressure related to the design and determining
the overall integrated leakage rate.'
intensity, radiant: The luminous flux per steradian emanating from a visible source, measured in lm-sr'". Also,
from a nonvisible source, the radiant flux per steradian
emanating from that source and measured in Wsr".
interface: The boundary between two adjacent media.U?
interface triggering: In ultrasonic testing, triggering the
sweep and auxiliary functions from an interface echo
occurring after the initial pulse. Also called IF synchronization.'
interference fitted thread: See Lnterjerence sealing
ffimoo.
-
interference objective: Small, metallized glass mounted
in contact with the test object and adjustable for tilt to
control fringe spacing."
interference sealing thread: Piping seal using a tapered
connection made under great pressure, forCing mating
surfaces together more tightly than is possible by hand
alone. Compare gasket seal and metal-to-metal seal.S
intergranular corrosion: Corrosion occurring preferentially at grain boundaries.f
intergranular stress corrosion cracking: An anomaly
caused by intergranular corrosion as a result of sensitized material, stress and corrosive environment (typical in the heat affected zone of stainless steel welds).
interlaced scanning: A process whereby the picture
appearing on a video screen is divided into two parts.
Interlaced scanning reduces flicker by increasing the
electron beam's downward rate of travel so that every
other line is sent. When the bottom is reached, the
beam is returned to the top and the alternate lines are
sent. The odd and even line scans are each transmitted
at 1/60 s, totaling 1130 s per frame and retaining the
standard rate of 30 frames per second. The eye's persistence of vision allows the odd and even lines to appear
as a Single image without flicker.s
internal conductor: See central conductor.
NONDESTRUCTIVE TESTING GL.OSSARY I
interpretation: The determination of the significance of
J
test indications from the standpoint of their relevance
or irrelevance. The determination of the cause of an
Jaeger eye chart: An eye chart used for near vision
indication or the evaluation of the significance of disexaminations,"
continuities from the standpoint of whether they are
joint: The part of the mold where the cope and cheek,
detrimental or inconsequential.t
and drag or cheek and drag come together. 3
interstitial alloy: Alloy in which the atoms of the alloying
joint efficiency: The strength of a welded joint expresse .~
element fit into the spaces between the atoms of the
as a percentage of the strength of the unweldedl ba<l
parent metal.'
i"':1
• metal.f
inverse segregation: Segregation in cast metal in which an . . ~oin~~enetration: The distance weld metal and
ext~d
into a joint. 2
excess of lower melting constituents occurs in the ear- .
..........
lier freezing portions, apparently the result of liquid
metal entering cavities developed in the earlier solidified metal.'
K
inverse square law: From a point source of radiation, the
intensity of energy arriving at a point of interest varies
Kaiser effect: The absence of detectable acoustic emission
as the inverse square of distance from source. 3.l 1
until the previous maximum applied stress level
investment casting: (1) Casting metal into a mold probeen exceeded.f
duced by surrounding (investing) an expendable patkeeper: Ferromagnetic material placed across the poles
tern with a refractory slurry that sets at room
a. .p e.,rman.ent magnet. to co~plete
the magnetic circ.l'~. .
temperature after which the wax, plastic or frozen merand prevent loss of magnehsm. 6 .15
' .••••
cury pattern is removed. Also called precision casting or
kinetic vision acuity: Vision acuity with a moving target.
lost wax process. (2) A casting made by the process.?
Studies indicate that 10 to 20 percent of visual effiinvestment compound: A mixture of graded refractory
ciency can be lost by target movement."
filler, a binder and a liquid vehicle, used to make molds
for investment castings."
investment molding: A method of molding by using a patL
tern of wax, plastic or other material invested or surrounded by a molding medium in slurry or liquid form.
laboratory microscope: Conventional compound microAfter the molding medium has solidified, the pattern is
scope. See microscope and microscope, compound. 8 1
removed by subjecting the mold to heat. Also called lost
lack of fusion: Discontinuity due to lack of union betwe i
wax process or precision molding. 3
weld metal and parent metal or between successive
ion current: The current that flows at all times from the
...
weld beads.? Also called incomplete penetration.
positive emitter (heater) to the negative cathode collecLamb wave: A type of ultrasonic wave propagationl
tor of the heated anode (alkali ion) halogen vapor
which the wave is guided between two parallel surface'~
detector. This current increases in the presence of haloof the test object. The mode and velocity depend on the
genated gases.l
product of the test frequency and the separati,l
ioniZing radiation: Any radiation that directly or indirectly
between the surfaces. Also called plate waves. 7
displaces electrons from the outer domains of atoms.
lambertian: Having a surface that diffuses light uniformly
Examples include alpha, beta and gamma radiation. 11
rather than reflecting it. Matte. Most objects
IQI: Image quality indicator. See penetrameter.
lambertian surface. Compare specular':
IR: Infrared and thermal testing.
laminated pole pieces: See articulated pole pieces.
iris: Ring of variable area around the pupil and in front of
lamination: Discontinuity in plate, sheet or strip caused BY
the lens of the eye. The surface area of the iris adjusts
pipe, inclusions or blowholes in the original ingot. Aft!·
spontaneously to change the amount of light entering
rolling, laminations are usually flat and parallel to thl
the eye. s
outside surface. Laminations may also result from pipe,
irradiance: Power of electromagnetic radiant energy inciblisters, seams, inclusions or segregation elongated ai
dent on the surface of a given unit area. Compare radiare made directional by working. Lamination discon ...
ance."
nuities may also occur in metal powder compacts. 2 May
Ishihara™ plates: Trade name for a kind of pseudoisochroappear in the form of rectangles or plates as indusi0~
matic plates. s
stringers between rolled surfaces. Short, intermitte!f
isotropy: A condition in which Significant medium properties
laminations may be detrimental if the object is suv~
(velocity, for example) are the same in all directions.'
jeeted to high bending stresses in service.f
~.
~ ~:_.'
J.:
. .•. .
.J
l
J
/ NONDESTRUCTIVE TESTING OVERVIEW
Surface discontinuity, usually parallel to the surface,
appearing as a fold or tangential seam in a wrought
product and caused by folding over of a hot metal fin or
sharp comer in a thin plate, then rolling or forging it
into the surface but not welding it. See also cold shut. 2.6
An acronym (light amplification by stimulated emission of radiation). The laser produces a highly monochromatic and coherent (spatial and temporal) beam of
radiation. A steady oscillation of nearly a single electromagnetic mode is maintained in a volume of an active
material bounded by highly reflecting surfaces, called a
resonator. The frequency of oscillation varies according
to the material used and by the methods of initially
"?
exciting or pumping the material. 8.:.W
"",Jeak: An opening that ~lows the passa?e of a flu~d. 1.27
teak detector: A device for detecting, locating, and/or
'~.
measuring leakage.!
leak. testing ~LT): N ondes~ructive testing me~od for de~ect­
\ mg, locating or measunng leaks or leakage m pressunzed
or evacuated systems or cornponents.! -I.'
.. akage: T.-he. measurable quantity of fluid escap.ing from a
leak.!
eakage design basis accident: The calculated peak containment internal pressure related to the design basis
. , ],
accident.'
1~akage'field: See magnetic leakagefield.
leakage flux: Magnetic Ilux of the coil that does not link
with the test object. The magnetic flux that leaves a saturated or nearly saturated object at adiscontinuity"
leakage rate: The quantity of leakage fluid per unit time
that flows through a leak at a given temperature as a
result of a speoified pressure difference across the
leak.! See throughput. [eaker penetrant: A penetrant especially designed for leak
! detection. Z
_beches: Permanent magnets or electromagnets attached to
electrodes carrying magnetizing current, to provide
strong electrode contact,6.16
Fns: Translucent object that refracts light passing through
it in order to focus the light on a target.8
lens optics: See geometrical optics.
fvel, acceptance: In ?ontrast to ~ejection level, test level
above or below which, depending on the test parameter, test objects are acceptable..2
.tveI, rejection: The value established for a test signal
I above or below which, depending on the test parameter, test objects are rejectable or otherwise distinguished from the remaining objects..2 See level,
acceptance.
tffiing power: The ability of a magnet to lift a piece of fer, ritic steel by magnetic attraction alone. 6.l5
ftoff: Distance between the probe coil and the test
. object.'
liftoff effect: In an electromagnetic test system output, the
effect observed due to a change in magnetic coupling
between a test object and a probe coil whenever the
distance between them is varied. 4.!3
light: Radiant energy that can excite the retina and produce
a visual sensation. The visible portion of the electromagnetic spectrum, from about 380 to 770 nm. S•20
light adapted vision: See photopic vision.
light guide bundle: Bundle of filaments, usually glass, that
carries noncoherent light from a high intensity source
through a fiber optic borescope to illuminate the
object,"
light metal: One of the low density metals such as aluminum, magnesium, titanium, beryllium or their
alloys..2
lighting, back: Placement of light source and image sensor
on opposite sides of the test object, used when the silhouette of a feature is important. S
lighting, flash: See lighting, strobe.
lighting, front: Placement of light source and image sensor
on the same side of the test object. S
lighting, strobe: Lighting that flashes intermittently at a
rate that may be adjusted and is often perceived as a
flicker, used to image moving objects O[ still objects
with potential movement. S
lighting, structured: Combining a light source with optical elements to form a line or sheet of light. S
limited certification: Individuals who are certified onlv for
specific operations are usually called limited Level (I, II
or III) or are designated as having limited certification
because they are not qualified to perform the full range
of activities expected of personnel at that level of qualification."
line pair: Pair of adjacent, parallel lines used to evaluate
the resolution of a specific imaging system. See also
minimum line pair.8
linearity, amplitude: A measure of the proportionality of
the signal input to the receiver and the amplitude of the
signal appearing on the display of an ultrasonic instrument or On an auxiliary displayJ23,24
linearity, area: In ultrasonic testing, constant proportionality between the signal amplitude and the areas of equal
discontinuities located at the same depth in the far
field. Necessarily limited by the size of the ultrasonic
beam and configuration of the reflector. 7
lines of force: A conceptual representation of magnetic flux
based on the line pattern produced when iron filings are
sprinkled on paper laid over a permanent magnet. 6.l 6
lipophilic removers: An oil base material that disperses
into a penetrant through solvent action, creating a mixture that is emulsifiable in water, facilitating its removal
by a water wash..2
NONDESTRUCTIVE TESTING GLOSSARY
liquid crystals: Cholesteric liquids whose optical properties cause them to reflect vivid spectral colors for temperature changes. Their adjustable response is sensitive
and can be made to change from red to blue over a ternperature gradient as small as 1 °C (1.8 °F).9
liquid penetrant: See penetrant.
liquid penetrant testing (PT): Nondestructive testing
method using penetrant.
location plot: A representation of acoustic emission
sources computed using an array of transducers.P
logarithmic decrement: The natural logarithm of the
ratio of the amplitudes of two successive cycles in a
damped wave train."
longitudinal direction: The principal direction of flow in a
-worked metal.f
longitudinal magnetic field: A magnetic field wherein
the flux lines traverse the component in a direction
essentially parallel with its longitudinal axis.6.l 6
longitudinal magnetization: Magnetization in which the
flux lines traverse the component in a direction essentially parallel to its longitudinal axiS. 6. 15
longitudinal wave: See compressional wave. 7
loose piece: A core positioned near, but not fastened to, a
die and arranged to be ejected with the casting. The
loose piece may be removed and used repeatedly for
the same purpose. Also, it is similarly used in or on patterns, core boxes and permanent molds.?
loss of back reflection: Absence or significant reduction of
an indication from the back surface of the test object. 7.10
lost-wax process: An investment casting process in which a
wax pattern is used."
lot tolerance percent defective: In quality control, the
percent defective at which there is a 10 percent probability of acceptance in a production run.f
low pass filtering: A linear combination of pixel values to
smoothen abrupt transitions in a digital image. Also
called smoothing. 8
LOX-safe penetrant: A penetrant material or system
specifically designed to be compatible with or nonreactive in the presence of liquid oxygen. 2
LT: Leak testing.
lumen: Luminous flux per steradian from a source whose
luminous intensity is 1 candela. Symbolized lm. S
lumen method: A lighting design procedure used for predetermining the relation between the number and
types of lamps or luminaires, the room characteristics
and the average illuminance on the work plane. It takes
into account both direct and reflected flux. Also called
flux method. 8.20
luminance: The ratio of a surface's luminous intensity in a
given direction to a unit ofprojected area. Measured in
candela per square meter. 8
luminosity: The luminous efficiency of radiant energy. 8
I
~...
luminous efficacy: The ratio of the total luminous flux
light source to the total_ radiant flux or to the no'N'i"l,i(m~
input. Sometimes called luminous efficiency. 8
luminous efficiency: See luminous efficacy.
luminous flux: Radiant energy's time rate of flow.
sured inlumens.f
luminous intensity; Luminous flux on a surface normal
the direction from its light source, divided by the
angle the surface subtends at the source. Measured
. .ca,.ndela. Also known as candlepouec"
Itx: T:1l1it of measure for illuminance in SI. Equivalent
lum~}iS'per square meter and symbolized lx. J:<·o!rrnler.l.U.~
known as meter-candle. S
M
machine "i.sion: Auto.ma.ted.system..... function of acquin.:n(w.l.•
processmg and analyzIng Images to evaluate a test objet I
or to provide information for human intexpretation. A
.kal sy~t~.~ co.nsists.:Of. a light sour,ce., a Vl._.· ~eo. c.a
..men."'!
a Video digttiZer, a computer and an Image display.s
macroshrinkage: A casting discontinuity, detectable at
magnifications not exceeding ten diameters, consisting
of voids in.the form. o. f stringer.•.s shorter than s.hrinkag....
cracks. This discontinuity results from contraction du !
ing solidification where there is not an adequate opportunity to supply filler material to compensate for
shrinkage. It is usually associated with abrupt change
in section size. 2.3
macrostructure: The structure of metals as revealed
examination of the etched surface of a polished obje
at a magnification not exceeding ten diametersf
macular lutae: Irregular, diffuse ring of yellow pigment
which partly overlaps the fovea and surrounds it
around 10 degrees and which absorbs blue light,
changing the color of the light reaching receptors
beneath.s
magnetic circuit: The closed path followed by any grot
of magnetic flux lines. 6 .15
magnetic field: Space in which the magnetic force _j~
exerted within and surrounding a magnetized object. 6· i
magnetic field indicator: A device used to locate or dete..
mine relative intensity of a flux leakage field. 6,16
magnetic field leakage: See flux leakagefield.
'l
magnetic field strength: The measured intensity of ..
magnetic field at a specific point. Expressed in amperes
per meter or oersted."
magnetic flow technique: Closing the magnetic circuit
an electromagnet with a test object or portion
Resulting field is longitudinal in direction." See longitudinal magnetization.
magnetic flux: The total number of lines of magnetic
existing in a magnetic circuit. 6.l5
typ
.
J
I·
J
l
/ NONDESTRUCTIVE TESTING OVERView
,i\.;~.;~agnetic flux dens~ty:·The normal m~gnetic flux per unit
,.r-
area. Expressed III tesla or gauss.6,l.~
magnetic flux leakage: See flux leakage field.
Si')~nagnetic leakage field: See flux leakage field.
jnagnetic leakage flux: Exiting of magnetic lines of force
from the surface of a test object,4.l4
·r.·
•. . . ., agnetic. particl.e. test syst.e
. . m:. Equipmen.t p.roviding the
i
electric current and magnetic flux necessary for magnetic particle discontinuity detection. 6.15
magnetic particle testing (MT): A nondestructive test
method using magnetic leakage fields and indicating
materials to disclose surface and near surface discontinuities. 6.l 6
pagnetic particles: Finely divided ferromagnetic material
l capable of being individually magnetized and attracted
\ to flux leakage fields. 6J6
Tagnetic permeablllty. See permeabtlitu.
ragnetic ~owd~r: Magnetic pa~icles in dry. or p~w~er
form WIth SIze and shape SUItable for discontinuity
detection. 6 .l 5
. ·.~agnetic rubber: A specially formulated testing medium
I containing magnetic particles. Used to obtain replica
castings of component surfaces with discontinuities
'j
being reproduced within the replica. 6.l 5
~agnetic saturation: That degree of magnetization where a
, further increase in magnetizing force produces no sigruficant increase in magnetic flu£density in an object,4JS
ragnetic writing: A non relevant indi?ation :ometimes
.I
caused when the surface of a magnetized object comes
in contact 'with another piece of ferromagnetic material
or a current carrvinz
cable. 6.16
--'"
0
J.agnetism:
(I) The ability of a magnet to attract or repel
J
another magnet or to attract a ferromagnetic material.
(2) A force field surrounding conductors carrying electric ~urr.ent.6.17
.
••-l.agnetization: The process by which elementary magnetic domains of a material are aligned predominantly
I in one direction. 6
lagnetizing current: The electric current passed through
or adjacent to an object that gives rise to a designated
I
magnetic field. 6
lagnetizing force: .The ma~etizjng field strengt~ apglied
to a ferromagnetic matenal to produce magnetism..16
~agnetometer: A device for m_easuring the strength of
i magnets or magnetic fields. 5.1 1
lagnitude: The absolute value of a complex number without reference to the ,phase of the quantity."
~alleahility: The characteristic of metals that permits plasl tic deformation in compression without rupture."
malleable cast iron: A cast iron made by a prolonged
anneal of white cast iron in which decarburization or
graphitization or both, take place to eliminate some or
all of the cementite. The graphite is in the form of temper carbon.f
1.
I
manipulator: In immersion testing, a device for angular orientations of the transducer. i.~l
manometer: Instrument, usually a U shaped tube containing water or mercury, for measuring pressure (or pressure differentials) of gases and vapors. The difference
in liquid column height in the two vertical arms of the
U-tube indicates the pressure difference. I
manual zero: A control on a test instrument that allows the
user to zero the instrument panel meter,'
.
markers: In ultrasonic testing, a series of indications on the
horizontal trace ofa display screen that show increments
of time or distance.'·21
martensite: (1) Acicular (needlelike) microstructure produced by fast cooling or quenching of metals and alloys
such as steel. (2) The hard steel with such microstructure produced by fast cooling of austenite,"
.
mask: (I) A spatial filter in the sensing unit of a surface
inspection system. (2) An n x n square matrix with different values that serves as a filter in image prooessing.f
masking: The covering of a portion of a test object so as to
prevent tracer gas from entering leaks that may exist in
the covered section. 1
mass spectrometer leak detector: Mass spectrometer
with design factors optimized to produce an instrument
.
that has high sensitivity to a single tracer gas. I
match bend effect: Optical illusion whereby an _area of
uniform brightness appears to be nonuniform because
of contrast with the brightness of an adjacent area."
match plate pattern: A sand molding pattern partly on the
cope side and partly on the drag side of the plate that
forms the parting between the cope and drag sections
of the molding flask. Permanent forms for runners,
gates, sprue and riser locations and sometimes complete risers, are included. Such a pattern usually is
made of aluminum and is used extensively with molding
machines.'
match plate: A plate of metal or other material on which
patterns for metal castings are mounted or formed as an
integral part so as to facilitate the molding operation.
The pattern is divided along its parting plane by the
plate.'
material noise: Random signals caused by the material
structure of the test object.'? A component of background noise.'
material, ferromagnetic: A material that exhibits the phenomena of magnetic hysteresis and saturation and
whose magnetic permeability is dependent on the magnetizing force. 2
material, nonferromagnetic: A material that is not magnetizable and not responsive to magnetic field tests.f
mathematical morphology: Image processing technique
of expanding and shrinking. The basic operators in
mathematical morphology are dilation (expanding),
erosion (shrinking), opening and closing."
NONDESTRUC1IVI: II:) IINu
ULV,;),)",n. I
I
matte: Tending to diffuse light rather than reflect it; not
metallurgy; The science and technology of metals.f
shiny. AlSQ called lambertian. The term matte is genermicro: A prefix that divides a basic unit of measure by
ally applied to smooth surfaces or coatings. Compare
million.f
specular: s
mieroboreseope: See borescope, micro-.
maximum burst amplitude: The maximum signal amplitude within the duration of the burst.."
mierofissurei A crack of microscopic proportions.f
Maxwell's eqtlations: The fundamental equations of macromicrograph: A graphic reproduction of the surface of a
p.. re p.a.red object, u~ually _etched, at. a. magnificatic..• . •:.•.·•. •.
scopic electromagnetic field theory.4.14
mean free path: Average distance a gas molecule travels
greater than ten diameters, If produced by phot1j
between successive collisions with other molecules in"
. graphic means it is called a photomicrograph (not
the gas or vapor state. 1
..... .:pil!crophotograph).2
measurement system; The entire system from sensor to
'micr"O~~~~ty: -) Porosity visible only with the aid
mlcr"Osrope.display inclusive. l
mechanical properties: The properties of a material that
microscope: An instrument that provides enlarged imag~s
reveal its elastic and inelastic behavior where force is
of very small objects. S
J
applied, therebv indicating its suitabilitv for mechanical
microscope. compound: Conventional microscope, usiL~
applications (fdr example, modulus of elasticity, tensile
geometrical optics for magnification. Also called lobo_strength, elongation, hardness and fatigue limit)..2
ratoru microscope. S
,-,~
melting point coatings: Coatings that melt at some spemicroscope. interference: MagnifIer using the wav.1
cific temperature. Anomalies are usualiy associated
length of light as a unit of measure for surface contour
and other characteristics.f
"]
with a temperature increase, so the materials melt first
over anomalies. Melting point compounds also are
microscope, metallographic: Metallurgical microsco:..
comparatively insensitive and require relatively high
designed for both visual observation and photomicrogr~~hy ?f prepare,d su.n.aces of opa.qu.=.' materials. at .ma~.-'.l-""
surface temperatures,9
meniscus method: A convex glass lens placed in contact
nifications ranging from about 20 to about 3,0 '.
with an optically flat glass platen. A dyed liquid
diameters.? Also called a metallograph.
between lens and platen forms a meniscus shaped film
microscope, metallurgical; Microscope designed with
of liquid. This film has zero thickness at the central
features suited for metallography.s
point of contact between lens and platen. A nonfluoresmicroscope, phase contrast: Laboratory. microscope
cent or colorIess spot appears at this point of contact,
the spot diameter being a function of a dye constant
two additional optical elements to transmit both
and dye concerrtration.f
?Iffract~d an~ u~?iff~acted light, revealing refract!
. ..
.
f
index discontinuities m a completely transparent b .
mesOpIc., VISIon: Vision a.dap_ted to a.level 0 li2:ht b.etween
•
object,"c.
.
photopic at 3.4 x 10-2 cd.m~2 (3,2 x 10~3 cd·ft-2) and
scotopic at 3 x 10-'-5 cd.m- 2 (2.7 x 10-6 cd.ft-.2).8
microscope, polarizing; Microscope with polarizing
metal-to-metal seal: Piping seal in which the mating surments to restrict light vibration to a single plane )
faces on the external connection (the pin) and internal
studying material with directional optical properties.
fibers, crystals, sheet plastic and materials under strain
connection (the box) are machined to provide a pressured interference fit 360 degrees around the connecare rotated between crossed polariz~rs on. th~ micltion. Compare gasket seal and inteiference sealino
scope stage, they change color and intensitv m a" ¥
thread.8··
.
b
that is related to their directional properties."
l.
a
r
.r·.,-
'<
metallic discontinuity: A break in the continuity of the
metal of an object. May be located on the surface (e.g.,
a crackl o- deep in the interior of the object (e.g., gas
pocketl.?
. metallograph: Short term for metallographic microscope. S
metallographic microscope: See microscope, metallographic.
metallography: The science dealing with the constitution
and structure of metals and allovs as revealed bv the
unaided eye Or by such tools as lo~ powered magnifications, optical microscope, electron microscope and
X-ray diffraction. 2
metallurgical microscope: See microscope, metallurgical,
micr~sc.o.piC stresse~: R:sidu~ stresses that vary from tE.. •. ••.
r.·
SIan to compreSSion m a distance (presumablyapprcjmating the grain size) that is small compared to the
gage length in ordinary strain measurement. Henp",j,
not detectable bv dissection method. Can sometin •.~
J
:.
be measured by X-ray shift. 2
microsegregations: (1) Segregation within a grain, cry~t<u
or small particle. Also called COri~g.:1. (2) Extremely n.l~
row cracks, usually long and straIght, on the surfaces;Jf
highly finished wrought metals. Often very shallow,
their identitv must be established to ensure that
indications are not from detrimental cracks, deep
or long inclusion stringers."
-
I NONDESTRUCTIVE TESTING OVERVIEW
'i,!!ficroshrinkage: A casting discontinuity, not detectable at
mold: A form or cavity into which molten metal is poured
u,;1
to produce a desired shape. Molds may be made of
sand, plaster or metal and frequently require the use of
cores and inserts for special appllcatlons.s-'
mold jacket: Wood or metal form that is slipped over a
sand mold for support during pouring. 3
mold wash: An aqueous or alcohol emulsion or suspension
of various materials used to coat the surface of a mold
cavity.3
molding machine: A machine for maldng sand molds by
mechanically compacting sand around a pattern.P
molecular flow: Phenomenon occuring when mean free
path length of gas molecules is greater than the largest
cross sectional dimension of a leak or the tube through
which flow is occurring. 1
molecule: A group of atoms held together by chemical
forces. The atoms in the molecule may be identical (H 2
and 5 s) or different (H 20 and CO2).2
monochromatic light: Light from a very small portion of
the visible spectrum. 8
monoehromatori Device that uses prisms or gratings to
separate or disperse the wavelengths of the spectrum
into noncontinuous lines or bands."
mottle: An apparently random positioning of metallic flakes
that creates an accidental pattern. 8
MT: Magnetic particle testing.
multiaxial stresses: Any stress state in which two or three
principal stresses are not zero. 2
multidirectional field: A periodic magnetic field that produces magnetization in two or more mutually perpendicular directions during a single cycle."
multidirectional magnetization: Two or more magnetic
fields in different directions imposed on a test object
sequentially and in rapid succession. 6.15
multifrequency: Two or more frequencies applied sequentially or simultaneously (as in a pulse).4
multifrequency technique: Utilization of the response of
a test object to more than one frequency, usually to separate effects that would be indistinguishable at a single
frequency. 4
multiparameter: The many parameters of a test system.
These parameters often affect test response and can
often be distinguished with a multifrequeney techniqne."
multiphase alloy: Alloy in which several phases are present,"
magnifications lower than ten diameters, consisting of
interdendritic voids. This discontinuity results from
contraction during solidification where there is not an
adequate opportunity to supply filler material to compensate for shrinkage. Alloys with a wide solidification
""
temperature range are particularly susceptible.s-'
.,~., icrostructure: The. struc~re of polished and. etc~ed
.1
metal as revealed by a rmcrosoope ata magnification
greater than ten dlameters.f
''lricrowave testing: Nondestructive testing method that
iii uses, for its probing energy, electromagnetic radiation
of frequencies from 0.3 to 300 GHz, with wavelengths
~1. ~rom 1 mm to 1 m. 4 .
~lmature angle be~ b~ock: A specific type of reference
standard used pnmarily for angle beam, but also for
_.
straight beam and surface wave calibration. i .12
~ature borescope,: See bo.,r~sco,'pe.sniniature.
Umborescope: Jargon for miniature borescope. 8
minimum line pair: The closest distance that a specific imagi~g sys~em c~ resolve betwe,en a"pair of adj,ace~t, parallel
lines (line pair) used to evaluate system resolution.f
misrun: A casting not fully formed, resulting from the
.
metal solidifying before the mold is filled. 3
K~A:.A sys~em of unit.s for :nechanics and. electromagnetTICS in which the basic units are meter, kilogram, second
and ampere. It is a constituent part of the 51 system of
units.4.14
ode: The manner in which an acoustic wave is propa1
gated, as characterized by the particle motion in the
wave (shear, Lamb, surface or longitudinal).7JO
~d~ conversion: A cha~ge of ultras~nic wave. propaga:
tion mode upon reflection or refraction at an interface.'
mode of vibration: Type of wave motion. Three common
modes used in ultrasonic testing are longitudinal, trans,·
verse and surface wave. 21
model, analytical: A representation ofa process or phei
nomenon by a set of solvable equations.v-?
IPd.ulus of e~asticity: The ~ati~ ~etwee~ stress and strain
s
III a material deformed within Its elastic range.
modulus of rupture: Nominal stress at fracture in a bend
1 test or torsion test.?
l~~bire: Optical patterns caused by the beating of two
superimposed gratings. Moire fringes usually appear
as alternating bright and dark bands on the image of
the specimen. The gratings can be real or virtual. For
analysis of in-plane deformations, a deformed specimen grating and an undeformed reference grating are
superimposed.?
I1bire interferometry: All moire techniques that require
physical optics for their explanation, particularly
diffraction and interference of light waves. It is known
by other names, including interferometric moire, high
sensitivity tnoireand diffraction moire. 9
,
.•
1
I,.
multiple back reflections: In ultrasonic testing, repetitive
echoes from the far boundary of the test object,l.lo
multivariablei See multiparametet.
mutual inductance: The common property of two electrical circuits whereby an electromotive force is induced in
one circuit by a change of current in the other circuit.4. 14
NONDESTRUCTIVt: I t:~ J INU
N
narrow handed: A relative term denoting a restricted
range of frequency response.U"
NDC: Nondestructive characterization.
NDE: (1) Nondestructive evaluation. (2) Nondestructive
examination .s
NDI: Nondestructive inspeetion.f
NDT: Nondestructive testing."
near field: The distance immediately in front of a transducer in which the ultrasonic beam exhibits complex
and changing wavefronts, Also called the Fresnel field
or Fresnel zone. 7.10
near surface discontinuity: A discontinuity not open to
but near the surface of a test object. Produces broad,
fuzzy, lightly held dry magnetic particle indications. 6 .16
near ultraviolet radiation: Ultraviolet radiation with
wavelengths ranging from about 320 to about 400 nm.
Sometimes called black light. 8
near vision: Vision of objects nearby, generally within arm's
length. Compare far vision. S
nearsightedness: Vision acuity functionally adequate for
viewing objects nearby, generally within arm's length
but not at greater distances. Also called myopia. Compare farsightedness. S
necking down: Localized reduction in area of a specimen
or structural member during welding or overloading. S.l9
negative sliding: The rolling and sliding of meshing gears
or rollers when the rolling and sliding are in opposite
directions.f
neper: The natural logarithm of a ratio of two amplitudes
(equal to 8.686 dB) used as a measure of attenuation.
Power ratios are expressed as half the natural Iogarithm.?
neural acuity: The ability of the eye and brain together to
discriminate patterns from background. Discrimination
is influenced by knowledge of the target pattern, by the
scanning technique and by the figure/ground relationship of a discontinuity.s
neutron: An uncharged elementary particle with a mass
nearly equal to that of the proton. The isolated neutron
is unstable and decavs with a half-life of about 13 minutes into an electron: proton and neutrino. 11
neutron radiography: Radiographic nondestructive testing using neutrons as the interrogating particles.
nick: Surface indentation caused by forceful abrasion or
impact. Also called gouge. Compare tool mark. S
nit: A former unit: for measuring luminance, equivalent to
one candela per square meter. Abbreviated ntf'
noble metals: Cathodic metals (such as gold, platinum and
silver), which strongly resist corrosion,"
nodal points: In angle beam ultrasonic testing, the location
of reflections at opposite surfaces as a wave progresses
along a test object."
ULV,>.;)I'Ul. I
I
node: A point in a standing wave where a given characte
tic of the wave field has zero amplitude. i
nodular cast iron: A cast iron that has been treated while
molten with a master alloy containing an element
as magnesium or cerium to give primary graphite in
spherultic form. 3
noise: Any undesired Signals that tend to interfere with
mal reception or processing of a desired Signal. The
gin may be an electrical or acoustic source,
.~
dtscontinu.iti~s "or abrupt changes in properties of the
te~t material. /,1_
'ji
nondes~clive characterization (NDe): Branch of no:;1
destructive testing concerned with the description and
pr.ediction of material prope.rties and behaviors. of cOJ.
ponents and systems.
' i
nondestructive evaluation (NDE): Another term fd
nondestructive testing. In research and academic cO TIl.munities, the word evaluation is often prefem],
because it emphasizes interpretation by knowledgeabel
personnel. S
nondestructive examination (NDE): Another term
nondestructive testing. In the utilities and
industry, examination is sometimes preferred because
te.-.~ting can imply p. erform~nce. trials of pressure cO."..· .I.
tainment or power generation s y s t e m s . s , 1
nondestructive inspection (NDI): Another term for non~
destructive testing. In some industries (utilities,
tion), the word inspection often implies rnaintenan
for a component that has been inservice."
nondestructive testing (NDT): The determination of the
physical condition of an object without affecting tlt
object's ability to fulfill its intended function. Non(}
structive testing techniques typically use a probing
energy form to determine material properties or-l:9
indicate the presence of material discontinuities (S1 •.•~
face, internal or concealed). See also nondestructt(;~
evaluation, nondestructive examination and nondestructive insp:ction. S •
nonferromagnetic material: A matenal that IS not magJJtizable and essentially not affected bv magnetic fields.
Includes paramagnetic materials and diamagnetic
rialS. 4.l 3
nonrelevant indication: See indication, nonrelevant.
normal incidence: (1) A condition in which the axis of ... p
ultrasonic beam is perpendicular to the entry surfacf!f
the test object. (2) A condition where the angle of irtCfdence is zero."
normal induction: The maximum induction in a magnfF
material that is symmetrically and cyclically magk~2tized. 4.l4
.
normal permeability: The ratio of normal induction to ....je
corresponding maximum magnetizing force. In ani. 11tropic media, normal permeability becomes amatrix.t-v'
..1
~---~------------['.~
I NONDESTRUCTIVE TESTING OVERVIEW
~.~•!. r,i.'orma~zed ~pedance diagram: In, electromagnetic
,...1
testing, an Impedance curve from which the effects of
frequency on a probe in air have been removed. Usually
the plotted data are (1) the measured reactance divided
by the reactance of the coil in air versus (2) the measured resistance less the resistance in air divided bv the
, coil reactance in air,"
. " .
lrmalizing: Heating a ferrous alloy to a suitable temperaii ture above the transformation range and then cooling in
,
~r to a teIUferature substantially below the transformaJ tion range.
'IR: Neutron radiographic testing.
null: To adjust a bridge circuit so that the test sample and
·,~,','·.·"L.' re.fe.rence
arms pro.d.uce e.. qual and OPP.osi.te current.s
through the.detector. 4
11
signal: A fixed component of a test coil signal that is
subtracted from the output signal leaving only that part
of the signal that varies with test object conditions."
.• i· merleal analysis: A technique to generate numbers as
the solution to a mathematical model of a physical svstern. Used in place of a closed form analytic expression.
Usually requires digital computation."
•.
1
o
. Jjective: In ~scussion of a lens system (:a.mera,
- borescope, mICroscope, telescope), of or pertammg to
the end or lens closest to the object of examination ~
_at the end opposite from the eyepiece. Distal; tip,S
8
C, .: , TG: Oil country tubular goods.
oersted: The cgs unit of magnetic field strength, abbreviated Oe. In. air, 1 Oe '" 1 ga.uss. Replaced by S1's ampere
. per meter. 6•15
[')' country tubular goods (OCTG): Hollow cylindrical
• co.mpo.n..e.n._ts used to convey. pe.troleum.·. and related
prodncts.s
:...Je .hundred percent testing: Testing of all parts of an
entire production lot in a prescribed manner. Sometimes, complete testing entails the testing of only the
critical portions ofthe part. Compare sampling, partial. 1>
>pen sand casting: Any casting made in a mold that has no
I cope or other covering.'
rning~ I~age. pr,ocessing operati~:>n. of er~sion foll~wed
by dilation. A smgle opemng eliminates Isolated smgle
.
pixels. See also closing.S
~in: See visual purple.
:ltic disk: Area in the retina through which the fibers from
the various receptors cross the inner (vitreous humor)
! side of the retina and pass through it together in the optic
.J . nerve bundle. This transitional area is completely blind.s
ptimum frequency: The frequency that provides the
highest signal-to~noise ratio compatible with the detection of a specific discontinuity. Each combination of
discontinuity type and material may have a different
optimum frequency.7.l2
b
'.
J
organoleptic: Relying on or using sense organs, such as the
human eye. s
orientation: The angular relationship of a surface, plane,
discontinuity or axis to a reference plane or surface. 7.IO
orthicon: See image orthicon.
oscillogram: Common term for a record or photograph of
data displayed on the cathode ray tube face.7.l2
ounces per year (oz/yr): Units defining the size of a leak
as the weight of refrigerant gas that will pass through
the leak in one year.l
outgassing: Forms of gas coming from material in a vacuum system. Includes gases adsorbed on the surface,
dissolved in material, trapped in pockets and those due
to evaporation or condensation. 1
overall integrated leakage rate: The total leakage
through all leakage paths including containment welds,
valves, fittings and components that penetrate a primary reactor containment system, expressed in weight
.
percent of contained air mass per day. I
p
pancake coil: A probe coil whose axis is normal to the surface of the te-st material and whose length is not larger
than the radius."
parafoveal vision: See scotopic vision.
parallax: The apparent difference in position of an imaged
point according to two differently positioned sensors."
parallel mag-netization: A magnetic field induced in magnetizable material placed parallel to a conductor carrying an electric current. 10 Not a recommended practice
for magnetic particle testing."
paramagnetic material: In electromagnetic testing, a
material that has a relative permeability slightly greater
than unity and is practically independent of the magnetizing force. 4 ,l .3
parameter distribution: A display of the number of times
the acoustic emission parameter falls between the values x and x -+ Ox as a function of x. Typical parameters
are amplitude, rise time and duration."
parasitic echo: See spurious echo.
particle motion: Mov~ment of particles of material during
wave propagation.'
parting line: The mark left on the casting where the die
halves meet. Also, the surface between the cover and
ejector portions of the die.3
parting sand: Fine sand for dusting on sand mold surfaces
that are to be separated.'
parts per million (ppm): Concentration of a specific gas in
another gas or gas mixture, For example, a tracer gas
concentration might be 10 ppm in air Or nitrogen. The
mare specific term JlUL is often used, with ppm to
indicate proportion by volume.'
NONUJ:~ I KU\.IIVI:: 11:.3! " ..... "".........., ....
pass: In welding, a single bead along the entire weld length
penetration time: The time allowed, after penetrant
or the process of laying down that bead. S
.
been applied to a surface, for the penetrant to enter
pattern: A form of wood, metal or other material, around
continuities that may be present. The length of
which a molding material is placed to make a mold for
elapsing between the application of the penetrant
casting metals. 3 · ·
the test object and the removal of the penetrant.f
pearlite: Platelet mixture of cementite and ferrite in steels
penetration, ultrasonic: Propagation of ultrasonic enl~rE··~·~
or in alpha and beta phases in nonferrous alloys."
into a material. See also effective penetration.'
peeling: (1) The dropping. away of sand from the casting
period: The absolute value of the minimum inteVlrv,aal·~tbril
which the same characteristics of a periodic v'
d. uring shakeout.
I
(2) The detaching of one layer of a ..
coating from another or from the basic metal, because .'._ . or a periodic feature return.t-l"
of pQoradherence.?
. perip'11eral vision: The seeing of objects displaced
t.he.p.p'ffiary line of Sight and outside the central
pencLI source: An arti ficial source using the fracture 0 f a
field.8.~
brittle graphite lead in a suitable fitting to simulate an
. . .
acoustic emission event. 5
permanent magnet: An object possessing the ability
retain an applied magnetic field for a long period
penetrability: The condition of being penetrable so that
time after the active power of the field has
liquid can enter into very fine openings such as cracks.
removed.v-?
Often erroneously used to describe the property of a
permanent mold: A metal mold of two or more parts
pene~ran\ that causes it to find its way into very fine
repeatedly for the production of many castings of t
opemngs.same form.'
penetrameter: A strip of metal the same composition as
permeabili.·ty: (1) A ?en.eral. t~.rm for various r~l~tionshi.c.-c.".l.'.
that of the metal being tested, representing a percent-between magnetic induction and magnetIzmg fonl.
age of object thickness and provided with a combmaThese relationships are: (a) absolute permeability (the
tion of steps, holes or slot or alternatively made as a
quotient of a change in magnetic induction divided
wire, When placed in the path of the rays, its image
the corresponding change in magnetizing force):,
provides a check on the radiographiC technique
(b) specific (relative) permeability (a pure number that
employed. 3 .11 Also called im.age quality-indicator.
is the same in all unit systems). The value and dim~~penetrant: A liquid capable of entering discontinuities
Sio~ of absolute permea?ility d~pend ~n. the syste.n:.. . ·..1f
open to the test surface and that is adapted to the peneunits employed. In anisotropic media, permeabf
trant test process by being made highly visible in small
becomes a rnatrix.v'" (2) The characteristic of materials
traces. Fluorescent penetrants fluoresce brightly under
th.at ..allows .ga.ses or liqUi~. S. to pass throub.~~ the.r~.'.~.
ultraviolet light and visible penetrants are intensely col(3) The ratio of flux density B to magnetizing fI F
ored to be readily visible on developer backgrounds
strength H. High permeability materials are easiertfo
when illuminated with visible light 2
magnetize than low permeability materials.f
penetrant comparator: See comparator; penetrant.
phantom: A reference standard used to verify the perf
penetrant leak testing: A technique of penetrant testing
mance of ultrasound systems. t
.
in which the penetrant is applied to one surface of a test
phase: In metallurgy, a physically homogeneous portion of
a material system, specifically the portion of an a
material while the opposite surface is tested for indications that would identify a through leak or void passing
characterized by its microstructure at a particular
.
perature during melting or solidification.s
through the material thickness.f
penetrant testing: Nondestructive testing method using
phase analy.sis.: .An an~yt·.ical. :e.chnique. th~t dis.Crim.in,.. •·. . ·.•. .•~~s
between variables m an ob]ect undergom£:~ electron: : penetrant.
netic testing by the different phase angle changes that
penetrant, fluorescent: A penetrant characterized by its
h
di
d' h
al S
1
ability to fluoresce when excited bv ultraviolet lizht."
te.se con·ti.·on.s pro.uce m t e test sign. ee a.•...~.o
•
•
v
phase detection.4j.,
.!
penetrant, post emulsifiable: A penetrant that requires
phase angle: The angular equivalent of the time displ~t~the application of a separate emulsifier to render the
ment between corresponding points on two sine waves
of the same frequencyv'" .
excess surface penetrant water washable.f
penetrant, visible: A penetrant characterized by an intense
phase contrast microscope: See microscope, phase
visible color dye that allows it to give contrasting indicatrast.
tions on a white developer background.?
phase detection: 'The derivation of a Signal whose arr~i.
penetrant, water washable: A penetrant with built in
tude is a function of the phase angle between two alk
emulsifier that makes it directly water washable.f
nating currents, one of which is used as a reference.";~3
j
hI
l
'.'3,
~---"""""'=~~~~iiiiiiiiiiiiiiiiiiiiiiii1r:i­
..
;: ~
I
NONDESTRUCT'VE TEST'NG OVERVIEW
diagram: Graph showing the temperature, pressure
and composition limits of phase fields in a material system. Also called a constitution diagram. Compare equilibrium diagram. 8
shift: A change in the phase relationship between
two alternating quantities of the same frequency.4.l3
ehase velocity: The velocity of a single frequency continuous wave."
Ii ase-sensitive system: A system whose output signal is
- dependent on the phase relationship between the volt-
1
·~
age retume.d. 4fr,?m a pickup or sensing coil and. a reference voltage. ,l cl
.
phased array: A mosaic of transducer elements in which
.. the timing of the elements' excitation can be individually controlled to produce certain desired effects, such
as steering the beam axis or focusing the beam.'
phasor quantity: Any quantity that is expressed as a com1 plex number. See impedance. 4.15
FPtoconduction: Method by which a vidicon television
camera tube produces an electrical image, in which conductivity of the photosensitive surface changes in relation to intensity of the light reflected from the scene
focused onto the surface. Compare phatoemission. 8
f>J:t?toelasticity: The effect of a material's elastic properties
I on the way that it refracts or reflects light. s
) htoelecmc effect: Emission of electrons from a surface
bombarded by sufflciently energetic photons. Such
. 'll.emissions :nay be, used i~ an illuminance meter and
may be calibrated m IlLX.8._0
.
)notoemission: Method by which an image orthicon television camera tube produces an electrical image, in
1,,:hich .a photosensitive. surface ~mi~s electrons when
J light reflected from a viewed object IS focused on that
surface. Compare photoconduction. 8
I~ )tometer: The basic measuri~g inst~ment of p~10t?me­
J try. Accurate meters measunng radiant energy Incident
on a receiver, producing measurable electrical quanti.
8
.
I ties.
] J1tometric brightness: The luminance of a light souroe.f
h •tometry: The science and practice of the measurement
of light or photon-emitting electromagnetic radiation.
1See also relative photometry. 8
I .lton: Particle of light,S
hotopie vision: Vision adapted to daylight and mediated
[mainiy by the cones. Vision is wholly photopic when the
jluminance of the. test surface is above 0.034 cd-rn?
(0.0032 cd·ft-'!). Also known as foveal vision and light
jadapted vision. Compare mesopic vision and scotopic
luision. S,20
~vtoreceptor: Light sensor,"
.
iysical properties: Nonmechanical properties such as
\densitY, electrical conductivity, heat conductivity and
!thermal expansion, 2
eture element: See pixel.
II
..•.· ......•.••
l
•...
••.•
·•••
.·••.•...
·
picture processing: See image processing.
piezoelectric effect: The ability of certain materials to
convert electrical energy into mechanical energy and
vice versa, i.12
pinhole porosity: Porosity, in either castings or metal
.. formed by electrodeposition, resulting from numerous
small holes distributed throughout the metal."
pipe: (1) The central cavity formed dUring solidification of
metal, especially ingots, by thermal contraction. (2) The
discontinuity in wrought or cast products resulting from
such a cavity. (3) An extrusion discontinuity due to the
Oxidized surface of the billet flowing toward the center
of the rod at the back end. (4) A cast, wrought or
welded metal tube. 2
pitch and catch: Test technique in which ultrasonic energy
is emitted by one transducer and received by another on
the same or opposite surface.P Also called pitch-catch,
two transducer technique or dual crystal method.'
pitting: Discontinuity consisting of surface, cavities. See
also cavitation fatigue and pitting fatigue. S
pitting fatigue: Discontinuity consisting of surface cavities
. typically due to fatigue and abrasion of contacting surfaces undergoing compressive loading. See also cavitation fatigue and pitting. 8
pixel: A lighted point on the screen of a digital image. Picture element. S
Planck's Distribution Law: The distribution criterion for
blackbody radiation.
plane of focus: See focus, principal plane of
plane wave: A wave in which points of same phase lie on
parallel plane surfaces.U"
plaster molding: Molding where a gypsum bonded aggre~
gate flour in the form of a water slurry is poured over a
pattern, permitted to harden and is thoroughly dried
after removal of the pattern. The technique is used to
make smooth nonferrous castings of accurate size.3
plastic deformation: Deformation that does or will remain
permanent after removal of the load that caused it. 2
plate wave: See Lamb wave.
platelet: Flat crystallites in certain phases of steel,"
plunger machines: Die casting machines having a plunger
in continuous contact with molten metal.'
point of incidence: In ultrasonic testing, the point at
which the center of the sound beam leaves the plastic
wedge of an angle beam transducer and enters the test
object. 12 See probe index.'
polarizing microscope: See microscope, polarizing.
pole: See magnetic pole.
poling: The process of reorienting crystal domains in certain materials by applying a strong electric field at elevated temperatures. Materials (usually ceramics) so
treated exhibit piezoelectric behavior,"
NONDESTRUCTIVE TESTING GLOSSARY I
pores: (1) Small voids within a metal. (2) Minute cavities,
some~mes intenti0r:al, i~ a powder metallurgy ~om.ract.
(3) Minute perforations in an electroplated coating.~
porosity: A discontinuity in metal resulting from the ereation or coalescence of gas. Very small pores are called
pinholes. S.19
positive sliding: The rolling and sliding of meshing gears
or rollers when directions of rolling and sliding are the
same. s
postcleaning: The removal of penetrant testing residues
from the test piece after penetrant test processing is
completed.'
-
postemulsification: A penetrant removal technique
employing a separate emulsifier applied over the surface penetrant to make it removable with water spray.2
poultice corrosion: See corrosion, poultice.
pouring basin: A basin on top of a mold to receive the
molten metal before it enters the sprue or downgate. 3
pouring: Transferring molten metal from a furnace or a
ladle to a rnold.'
powder: See dry powder:
powder blower: A compressed air device used to apply dry
magnetic particles over the surface of a test object. 6,16
practical examination: In certification of nondestructive
testing personnel, a hands-on examination using test
equipment and sample test objects. Compare general
examination and specific examination. S
precleaning: The removal of surface contamination or
smeared metal from the test piece so that it cannot
interfere with the penetrant testing process.f
pressure testing:. A technique ofleak testing objects pressurized with a tracer gas with the subsequent detection
and location of any existing leaks with a sampling probe
(a qualitative test). Tests performed by increasing the
pressure inside a test boundary to a level greater'than
the surrounding atmosphere and detecting leakage by
svstematic examination of the outside of the test surf~ce. Leaks are located at time of detection; however, it
is impossible to accurately determine a total leakage
.
rate for the object being tested. 1
prewash technique: Penetrant system in which major por~
tion of a nonwater washable penetrant is removed with
a water spray prior to application of the remover'
primary creep: First stage of creep, marked by elastic
.
strain plus plastic strain.f
primary radiation: Radiation emitting directly from the
target of an X-ray tube or from a radioactive source. 11
primary reference response level: The ultrasonic
response from the basic calibration reflector at the
specified sound path distance, electronically adjusted to
a specified percentage of full screen height. 7
principal plane of focus: See focus, principal. plane of
probe: In leak testing, the physical means for sensing
gaseous leak, typically a tube having a fine opening
one end, used for directing or collecting a stream of
tracer gas. Dete.ctor probes are used or pr~ssure testin•....
·.•.'•.:t
and tracer probes are used for vacuum testing. I In ultra-ir;ttli
sonic testing, see search unit. 7
probe coll: In electromagnetic testing, a small coil or
assembly that is placed on or near the surface of
.
objects.4,l3
probe coil clearance: The perpendicular distance between
J",
adJilcen~ surfaces of the probe and test object. See
.fI.
off. 4,1:'", .• -'.
probe gilS: A tracer gas that issues from a fine orifice so as
to impinge on a restricted (small) test area.
probe index: The point on.a shear wave or surface waV:f.
transducer through which the emergent beam axis ~
I]\:
passes.il"
process: Repeatable sequence of actions to bring about
desired result."
process control: Application of quality control principles
~,
to the management of a repeated process."
process testing: Initial produet testing to establish correc.:.•
manufacturing procedures and then by periodic tests to
ensure that the process continues to operate correctly.~,
prod magnetization: See currentflow technique.
]
prods: Handheld electrodes for transmitting magnetizing'"
current from a generating source to a test object,6.15
production string: See tubing string.
propagation: Advancement of a wave through
medium.i-'?
. :. be.: A. probe that can vary the tr,ace.:. r.· .ga..".·. I•. .•
prop.o.m.·onin~ p.ro
concentration In the sample at the sensor, typically b
mixing pure air with sample gas from the probe inlet'
port. Ratios of mixture between 100 percent pure
(obt~ned.· from a.n outdoors source or by filtering am.. bi._
ent air through charcoal) and 100 percent leak sampl\",)1
gas are attainable without great changes in total flow
from the probe. The proportioning probe used in halo)~
gen leak testing lets the user operate in an atmospher'jl
with up to 1,000 IlUL (ppm) tracer gas background
contamination. It proportions the amount of atmort
sp~ere allowe? to enter the probe with its own (recircul
lating) fresh air s u p p l y . l " " ,
pseudocolor: Image enhancement technique wherein colors
are assigned to an image at several gray scale intervals. 8
pseudoisochromatic plates: Color plates used for coloL,~
vision examinations. Each plate bears an image which
may be difficult for the examinee to see if his or herl
color vision is Impaired."
}I
psychophysics: Interaction between vision performand:'!'~
and physical or psychological factors. One example i~
the so-called vigilance decrement, the degradation
reliability based on performing visual andlor repetitivLI
activities over a period of time. 8
,I
air.
il
cl
~-~--""""""'-...oiiiiiiiiii~iiiiiiiiiiiiiiiiiiiiiiiiiiiiliiiiiiiiiiiiii:: ~
I
I NONDESTRUCTIVE TESTING OVERVIEW
Liquid penetrant testing.
cracks: In a casting, cracks caused by residual stresses
produced by cooling because of the object shape."
~m~lulse: A transient electrical or ultrasonic signal that has a
rapid increase in amplitude to its maximum value, followed by an immediate return. 7 •21 An example is the
"~ ~J: ~·J~~:r.d~~~e:ri~~*;;cU=.n~d~~::.~ans.. 'l'.!
.
pulse echo method: An ultrasonic -test method in which
discontinuities are detected bv return echoes of the
""J transmitted pulses.'
~ulse length: A measure of tmlse duration expressed in
time or number of cycles.'·-I
-.,ulse magnetization: Direct or indirect application ofa
1 high field intensity, usually by the capacitor discharge
method,"
~p'ulse method: Multifrequency technique in which a
.•
broadband excitation such as an impulse is used. Either
.1
the frequency components are extracted and analyzed
or the interpretation is based directly on characteristics
-I of the time domain waveform."
tulse repetition frequency: See repetition rate.
pulse tuning: Control of pulse frequency to optimize sys,
tern response. 7
}ulser transducer: In .a~~ustic emission tes?ng, a trans..' ducer used as an artificial source of acoustic energy.s
fupil: Aperture in the center of an eye's iris, through which
.. l'
light focused by the lens passes. S
.'" ure air supply: In leak testing, air that has been cleaned
of halogen contamination by means of an activated
charcoal filter. This term is sometimes also used to
describe any nonreactive gas, such as nitrogen, that
contains no halogen contamination and to which the
leak detector is not sensitive. I
jurple: See visual purp~e. ' .
. .
.
r1yrometry: Type of radiation thermometer, glVmgreadings
for one point at a time, rather than imaging a scene in
the manner of an infrared video camera. The word
pyrometry means fire measurement. As the name
implies, pyrometers are used for hot applications, such
as the monitoring of furnace or foundry conditions.
Pyrometers today are digital devices with liquid crystal
temperature readouts. They may be mounted in place
or available as hand held unitsf
.t
Q
Q of a coil: Ratio of reactance to resistance measured at the
. operating frequency.4,14
iuadrature: The relation between two periodic functions
when the phase difference between them is one-fourth
of a period. 4.14
qualification: Process of demonstrating that an individual
has the required amount and the required type of training, experience, knowledge and capabilities. See also
qualified. 8
qualified: Having demonstrated the required amount and
the required type of training, experience, knowledge
and abilities. See also qualification. S
quality: The ability of a process or product to meet specifications or to meet the expectations of its users in terms
of efficiency, appearance, longevity and ergonomics.f
quality assurance: Administrative actions that specify,
enforce and verify a quality program. s
quality control: Physical and administrative actions required to ensure compliance with the quality assurance
program. May include nondestructive testing in the
manufacturing cycle."
quality of lighting: Level of distribution of luminance in a
visual task or environment. S
quartz Bourdon tube gage: High precision pressure measuring instrument containing a -quartz helical Bourdon
tube)
quasilongitudinal wave: A wave in which the direction of
particle motii'n is not parallel to the direction of energy
propagation.
quasishear wave: A wave in which the direction of particle
motion is no! perpendicular to the direction of energy
propagation. i
quenching of fluorescence: The extinction of fluorescence by causes other than removal of the ultraviolet
light (the exciting radiationj.?
quick break: A sudden interruption of magnetizing current. Used in magnetic particle tests for materials with
high residual longitudinal magnetism and limited to
three-phase fullwave rectified alternating current.6,I6
I
R
rad: Radiation absorbed dose. A unit of absorbed dose of
ionizing radiation. One rad is equal to the absorption of
10- 5 J (100 ergs) of radiation energy per gram of matter.!I Replaced by the gray (Gy).
radiance: Radiant flux per unit solid angle and per unit
projected area of the source. Measured in watts per
square meter steradian. Compare irradiance,"
..
radiant energy: Energy transmitted through a medium by
electromagnetic waves. Also known as radiation.8
radiant flux: .Badiant energy's rate of flow, measured in
watts."
radiant intensity: Electromagnetic energy emitted per
unit time per unit solid angle. Measured in watts per
steradian.f
radiant power: Total radiant energy emitted per unit time."
NONDESTRUCTIVE TESTING GLOSSARY I
radiation safety officer: An individual engaged in the
practice of providing radiation protection, The representative appointed by the licensee for liaison with the
applicable regulatory agency.ll
radio frequency display: The 'presentation of unrectified
signals on a display screen. i,l2 Also called RF display.
See also video presentation.
radiographic interpretation: The determination of the
cause and significance of subsurface discontinuities
indicated on a radiograph. The evaluation as to the
acceptability or rejectability of the material is based on
the judicious application of the radiographic specifications and standards governing the material.l!
radiographic screens: Metallic or fluorescent sheets used
to intensify the radiation effect on films.ll
radiographic testing (RT): The use of radiant energy in
the form of Xsrays or gamma rays for nondestructive
testing of opaque objects in order to produce graphical
records on a medium that indicates the comparative
soundness of the object being tested.!'
radiography: Radiographic testing.
radiology: That branch of medicine which uses ionizing
radiation for diagnosis and therapy. 11
radiometer: Instrument for measuring radiant power of
specified frequencies. Different radiometers exist for
different frequencies.f
radiometric photometer: Radiometer for measuring radiant power over a variety ofwavelengths,"
radioscopy: A radiographic testing technique in which
gamma rays or X-rays are used to produce an instantaneous image on a video or screen display as opposed to
a latent image on a film. The test object may be
remotely manipulated in real time to present a moving
radiographic image.
ramoff: A casting discontinuity resulting from the movement of sand away from the pattern because of
improper ramming?
range: In ultrasonic testing, the maximum path length that
is displayed. See also sweep length. 7.12
rarefaction: The thinning or separation of particles in a
propagating medium due to the relaxation phase of an
ultrasonic cycle, Opposite of compression. A compressional wave is composed of alternating compressions
and rarefactions. no
.
raster: A repetitive pattern whereby a directed element (a
robotic arm or a flying dot on a video screen) follows
the path of a series of adjacent parallel lines, taking
them successively in tum, always in the same direction
(from top to bottom or from left to right), stopping at
the end of one line and beginning again at the start of
the next line. Following a raster pattern makes it possible for electron beams to form video pictures or frames
and for a sensor bearing armature to cover a predetermined part of the surface of a test object."
rat's tooth principle: (1) The tendency for hard materti~l<
on a tooth's front surface to wear more slowly than
material on the back surface, keeping the edge sharp.
(2) Mechanism of wear whereby adjacent hard and stt
surfaces wear at different rates, producing a self sha1),,':ill
ening edge. s
'
Rayleigh wave: An ultrasonic wave that propagates ala
the surface of a test object. The particle motion is ell
tical in a plane perpendicular to the surface, decrea .
. ~ 'rapidly with depth below the surface, The effective
~p.th ..of penetration is considered to be about
wa\:,~,eftgth.7
real gnltitlg: In moire and grid nondestructive testing, a
.•,·. •',.
physical g,ra,ti~g, ,on glass. or other substrate. Two ~].i,.,
are the amplttude gratzng (or bar-and-space gratin,
consisting of opaque bars and clear spaces for use with
transmitted light, or reflective bars and nonrefleCtij'
spaces for use with reflected light; and the phase gn'
ing consisting of an array of furrows on the surface m:
transparent or opaque body?
recarhu~ze: (1) To increas~ the carbon.content of. mol:','.".',.~.l.•
cast Iron or steel by adding carbonaceous material, h16,'
carbon pig iron or a high carbon alloy. (2) To carburize
~n;;tal object to return surface carbon lost in proce~J
receiver: The section of an ultrasonic instrument tha!
amplifies echoes returning from the test object. Also:"l"
transducer that picks up the echoes.'
•
recommended practice: A set of guidelines or recons'
mendations.f
Recommended Practice SNT~TC-IA: See ASNT RecOJ ·.·. •l
mended Practice No. SNT-TC-1A.
'~
recovery: Reduced stress level and increased ductility of
metal after work hardening. See creep. 8
recovery time: The time required for a test system
return to its original state after it has received a
nal. 4•13
,
recrystallization: (1) The change.from one ~rainstructl
to another, as occurs on heating or cooling througlrA
critical temperature. (2) The formaticn of a new, str~~
free grain structure from that existing in cold work<~
metal, usually accomplished by h e a t i n g , 2 J
rectified alternating current: A unidirectional electric
current obtained by rectifYing alternating current
out the deliberate addition of smoothing to remove
inherent ripples. 6 ,15
red mud: .?ebris (usu.ally o>?des. of the contacting ~etaJ~.r
offretting wear, mixed WIth 011 or grease and retained !~
or near the site of its formation. See also cocoa. 8
. ,.!
reference blocks: A block of material containing artific~<¥
or actual cracks of various depths and widths used !.Ir
reference in defining the size and location of defects
areas in materials.f
J
1
I NONDESTRUCTIVE TESTING OVERVIEW
r;~eference coil: In electromagnetic testing, the section of
I
the coil assembly that excites or detects the electromagnetic field in the reference standard of a comparative
1;i'01 system:U 3
kference grating: In moire and grid nondestructive testing, an undeformed grating superimposed upon a spec'] Imen grating to create the moire."
.
jeference number: Number associated with the impedance of a coil adjacent to a test sample."
""r'.ference standard: A typical test object with known ami.
ficial or natural discontinuities of various specific sizes,
used as a basis for test comparisons, equipment calibration or determining the efficiency of the discontinuity
detection process. Also called reference or test panel,
reference or test block and reference or test piece.2 See
'"
also acceptance standard.
'1ference threshold: A prese.t volt~g~ lev~l tha~ has to be
exceeded before an acoustic emISSIOn SIgnal IS detected
and processed. This threshold may be adjustable, fixed
~l
or floating,"
,bflectance: The ratio of reflected wave energy to incident
wave energy. Also known as reflectivity. S
. ~flectiom A general term for the process by which the
I incident flux leaves a surface or medium from the incident side, without change in frequency. Reflection is
usually a combination of specular and diffuse reflection. B.2o
r
reflection probe: A coil system that utilizes both an excita. tion and a detection or sensing coil on the same side of
the sample." .
"
reflectometer: Photometer used to measure diffuse, specular and total reflectance. B
~flector: (1) In optical nondestructive testing, device used
, to redirect the luminous flux from a source by the process of reflection.B,zo (2) In ultrasonic testing, a discontinuity or object surface from which acoustic energy
returns to the sensor.
refracted beam: A beam that occurs in the second
medium when an ultrasonic beam is incident at an
acute angle on the interface between two media having
different sound velocities,7,12
~fraction: The change in direction of a wave as a beam
, passes from one medium into another having a different sound velocity. A change in direction and mode may
occur at any angle of incidence. At small angles of incidence, the original mode and a converted mode may
exist in the second medium.'
r~fractive index: The ratio of the velocity of an incident
1 wave to that of a refracted wave. It is known as the
i
refractive index of the second medium with respect to
the first."
I
reinforcement of weld: (1) In a butt joint, weld metal on
the face of the weld that extends out beyond a surface'
plane common to the members being welded. (2) In a
fillet weld, weld metal that contributes to convexity.
(3) In a flash, upset or gas pressure weld, weld metal
exceeding base-metal diameter or thicknessf
reject: An instrument function or control used for minimizing or eliminating low amplitude signals (electrical or
material noise) so that other signals may be further
amplified. Use of this control can reduce vertical linearityAlso called suppression. 7,12
rejection level: See level, rejection.
relative penneability: The ratio of the permeability of the
material to the permeability of vacuum. See pertneabilify.4
relative photometry: (1) Evaluation of a desired photometric characteristic based on an assumed lumen output of a test lamp. (2) Measurement of an uncalibrated
light source relative to another uncalibrated light
source.f
relaxation: Relief of stress by creep. Diminishing stress by
creep at constant strain frequently occurs in service.f
relay amplifier: An optional electronic module in some
heated anode (alkali ion) halogen vapor detector systems that amplifies the leak signal and initiates an automatic control. The control then either sounds an
audible alarm, flashes a signal light, stops a conveyor or
operates whatever other control actuator the user connects to this relay output signal. 1
relevant indication: See indication, relevant.
rem: Roentgen equivalent man. A unit of absorbed radiation dose in biological matter. It is equal to the
absorbed dose in rads multiplied by the relative biological effectiveness of the radiation.'!
remanent magnetism: See residual magnetic field.
remote viewing: Viewing of a test object not in the viewer's
immediate presence. The word remote previously
implied either closed circuit television or fiber optic
systems remote enough so that, for example, the eyepiece and the objective lens could be in different
rooms. High resolution video and digital signals can
now be transmitted around the world with little loss of
image quality. Compare direct viewing. S
repeatability: Ability to reproduce a detectable indication
in separate processings and tests from a constant
source. 1,2
repetition rate: The number of pulses gener.ated or transmitted per unit of time (usually seconds).'
replica: Piece of malleable material, such as polyvinyl or
polystyrene plastic film, molded to a test surface for the
recording or analysis of the surface microstrueture.f
replication: A method for copying the topography of a surface by making its impression in a plastic or malleable
material.f
NONDESTRUCTIVE TESTING GLO,))J\/(Y
f
response factor: The response of the halogen leak de
reserve vision acuity: The ability of an individual to maintor to 3 X lO-i Pa·m 3·s-1 (3 X 10-6 std cm3·s-1) of tr
tain vision acuity under poor viewing conditions. A
R·12 or less, divided by the response to the same (quanvisual system with 20/20 near vision acuity under
degraded viewing conditions has considerable reserve
tity of another tracer gas. Thus, the actual leakage> r~.
vision acuity compared to that of an individual with
of a dete~e.d leak will equal the indication of the det~.~,J,1
tor multiplied by the response factor of the speCIfic
20170 near vision acuity"
.
residual elements: Elements present in an alloy in small
halogen tracer gas used. The response factor of $ mjquantities, but not added intentionally''
ture of tracer and nontracer gases will be the responrrl
factor of the tracer divided by the fraction of tracer girl
residual magnetic field: The magnetism remaining in a
in the test gas (by volume). 1
ferromagnetic material after the magneti-Zing force is
6
lO
reduced to zero. •
. ~esP-On~e. Jun.ction: The. rati~ of response to ex.--.c._itatic.·.•·. •. '•,.~.•
residual method: Using the residual magnetic field of high
both,>expressed as functions of the complex fri'~
quency.4.l4
retentivity materials to trap magnetic particles and indicate discontinuities."
retentivity: A material's property of retaining residual
residual technique: Ferromagnetic particles are applied
netism to a greater or lesser degree. 6.1o to a test object after the magnetizing force has been disretina: In the eye, the tissue that senses light.s
eontinued.f
retinene: See visual purple.
resolution: An aspect of image quality pertaining to a sysRF display: See radio frequency display.
tem's ability to reproduce objects, often measured by
rhodopsin: See visual purple.
resolving a pair of adjacent objects or parallel lines. See
ring standard: See test ring.
also minimum line pair and resolving power. s
ringdown count: See acoustic emission count.
resolution, discontinuity: The property of a test system
ringing method: A test method for bonded structures
that enables the separation of indications due to disconwhich disbonds are indicated by increased amplitude of
tinuities located in close proximity to each other in a
,.. •.
ringing signalS.',12
2
test object.
ringing signals: (1) Closely spaced multiple signalseaus
resolution test: Procedure wherein a line is detected to
by multiple reflections in a thin material. (2) Signals
verify a system's sensitivity."
caused by continued vibration of a transducer.'·12
resolution threshold: Minimum distance between a pair of
ringing time: The time that the mechanical vibrations 0
points or parallel lines when they can be distinguished as
transducer continue after the electrical pulse
two, not one, expressed in minutes of arc. Vision acuity
stopped.,,12
in such a case is the reciprocal of one half of the period
rinse: Th 7 process . o.f re.m._oving .liq.uid p~netrant testi .
expressed in minutes.8 .2o
matenals from the surface of a test object by means . J
resolving power: The ability of detection systems to sepawashing
or flooding with another liquid, usually water.
rate two points in time or distance. Resolving power
wash, 2
Also
called
depends on the angle of vision and the distance of the
riser: A reservoir of molten metal connected to the casti
sensor from the test surface. Resolving power in vision
to provide additional metal to the casting, required
systems is often measured using parallel lines. Compare
the result of shrinkage before and during solidification'
8
resolution.
robotic
system: Automated system programmed to pi .~
resonance: The condition in which the frequency of a forcform
purposeful movements in variable sequences. 1l 1
ing vibration (ultrasonic wave) is the same as the naturod: Retinal receptor that responds. at low levels of lumiral vibration frequency of the propagation body (test
nance even below the threshold for cones. At these
object), resulting in large amplitude responses at that
els.there is no basis for perceiving differences in
frequency.7,10 .
and
saturation. No rods are found in the foveacenresonance method: A method using the resonance princi8 •20
tralis.
ple for determining velocity, thickness or presence of
roof angle: In a dual element delay line transducer,
laminar discontinuities.' .
angle by which the top surfaces of the delay line
resonant frequency: The frequency at which a body vitilted horizontally to direct the beams of the two ele:;brates, that frequency being sympathetic to the energy
ments to intersect at a specified zone in the medium. II
causing the vibration.
root
crack: A crack in either the weld or heat affected zo.,"~
response or response time: The time (time-constant)
at
the root of a we1d. 2
required for a leak detector or leak testing system to yield
root penetration: The depth to which weld metal
a signal output equal to 63 percent of the maximum siginto the root of a joint. 2
nal attained when tracer gas is applied continuously for
RT: Radiographic testing.
an indefinitely long period to the leak detector probe. 1
I
h~J
it.
I
NONDESTRUCTIVE TESTING OVERVIEW
!i't'unner: (1) A channel through which molten metal flows
from one receptacle to another. (2) The portion of the
gate assembly that connects the downgate sprue or riser
with the casting. (3) Parts of patterns and finished castings corresponding to the described portion of the gate
assembly'
""r"nner box: A distribution box that divides the molten
!.
metal Jnto several streams before it enters the mold
cavity."
'r~f~;: t~:~::~~~~ a casting caused by the escape
5
salvage tests: Testing after salvage operations or testing
objects that can be repaired,"
... amp~ng prob~: See de.tector probe.
sampling, partial: Testmg of less than one hundred per_
cent of a production lot. See one hundred percent testJ ing. 8
Jampling, random partial: Partial sampling that is fully
random.f
.... ]ampling, specified partial: Partial sampling in which a
j particular frequency or sequence of sample selection is
prescribed. An example of specified partial sampling is
,,'
the testing of every fifth unit. s
'
land: A granular material resulting from the disintegration
I
of rock. Foundrv sands are mainlv silica. Bank sands are
found in sedimentary deposits and contains less than .5
percent clay. Dune sand occurs in wind blown deposits
near large bodies of water and is very high in silica content. Molding sand contains more than 5 percent clay,
usually between 10 and 20 percent. Silica sand is a
granular material containing at least 95 percent silica
and often more than 99 percent. Sand core is nearly
pure silica. Miscellaneous types of sand include zircon,
. olivine, calcium carbonate, lava and titanium minerals:"
laturation: (1) A condition in which high amplitude signals
on a display screen do not increase with increased gain
and appear flattened.' (2) Relative or comparative color
characteristic resulting from a hue's dilution with white
light. s
"jaturation level: See magnetic saturation.
Icab: A flat volume of metal joined to a casting through a
J
small area. Usually set in a depression, a flat side being
separated from the metal of the casting proper by a thin
, layer of sand.'
icalar: A quantity completely specified by a single number. 4 .14
lcale: Oxide formed on metal by chemical action of the sur. face metal with oxygen from the air.2
~cale pit: Shallow surface depression in metal, caused by
scale.f
~'~'j
-
- - . I
- ---
-
-
-,;
-----
scaling: (1) Forming a layer of oxidation product on metals,
usually at high temperatures. (2) Deposition of insoluble constituents on a metal surface, as in cooling tubes
and water boilers. S.l 9
scanning: Movement of the transducer over the surface of
the test object in a controlled manner so as to achieve
complete coverage. May be either contact or immersion method.'
scarfing: Cutting surface areas of metal objects, ordinarily
by using a gas torch. The operation permits surface discontinuities to be cut from ingots, billets or the edges of
plate that is to be beveled for butt welding. 3
scattering: (1) Random reflection and refraction of radiation caused by interaction with material it strikes or
penetrates. (2) Random reflection of ultrasonic waves
by small discontinuities or surface irregularities.'
Schlieren system: An optical system used for visual display
of an ultrasonic beam passing through a transparent
medium.'·9J2
'
..
scoring: (1) Marring or scratching of any formed part by
metal pickup on a punch, die or guide. (2) Reducing the
thickness of a part along a line to weaken it purposely at
a specific location. S.l 9
scotopic vision: Dark adapted vision, using only the rods in
the retina, where differences in brightness can be detected but differences in hue cannot. Vision is whollv
scotopic when the luminance of the test surface is
below 3 X 10-5 cd·m-z (2.7 x 10-6 cd-fr"). Also known as
parafoveal vision. Compare mesopic vision and photopic vision. S
scrap: (1) Manufactured materials not suitable for sale.
(2) Discarded metallic material that may be reclaimed
through melting and refining.'
scuffing: A type of adhesive wear.
sea level atmospheric pressure or sea level barometric
pressure: See atmospheric pressure.
sealing: (1) Closing pores in anodic coatings to render them
less absorbent. (2) Plugging leaks in a casting by introducing thermosetting plastics into porous areas and
subsequently setting the plastic with heat.'
seam: (1) On the surface of metal, an unwelded fold or lap
that appears as a crack, usually resulting from a discontinuity obtained in casting or working. (2) Mechanical
or welded joints.' (3) Longitudinal surface discontinuity on metal originating from a surface crack or blowhole near the surface of the ingot, that is drawn out
during rolling and follows the rolling direction. Also
due to overfill while rolling.'After forging, seams generally follow the direction of flow lines. 2
search coil: A detection coil that is usually smaller than the
excitation coil."
'
NONDESTRUCTIVE TESTING GLOSSARY I
search unit: An assembly comprising a piezoelectric element, backing material (damping), wear plate or wedge
(optional) and leads enclosed in a hous.ing. Also called
transducer or probe.'
second stage replica: A positive replica made from the
first cast to produce a duplicate of the original surface.f
secondary creep: Second stage of creep, where deformation proceeds at a constant rate and less rapidly than as
in 'primary creep. Essentially an equilibrium condition
between the mechanisms of work hardening and recovery.s
secondary magnetic flux: magnetic flux due to induced
flow of eddy currents.f
seeability: The characteristic of an indication that enables
an observer to see it against the adverse conditions of
background, outside light etc. 2
segregation: Nonuniform distributio,? of alloying elements, impurities or microphases.V'
selectivity: The characteristic of a test system that is a measure of the extent to which an instrument is capable of
differentiating between the desired Signal and disturbances of other frequencies or phases. o 3
self emulsifiable: Describes a penetrant that spontaneouslyemulsifies into water, a property that allows it to be
rinsed off with water, with more control than if it actually dissolved in the rinse water. Also called water washable. See penetrant, water washable. 2
self inductance: The property of an electric circuit whereby an electromotive force is induced in that circuit by a
change of current in the circuit. 4 .l 4
semipermanent mold: A permanent mold in which sand
or plastic cores are used:'
send/receive transducer: A transducer consisting of two
piezoelectric elements mounted side by side separated
by an acoustic barrier. One element transmits, one
receives.i'?
sensing coils A coil that detects changes in the magnetic
field produced by the flow of eddy currents in a test
specimen, induced by an excitation coil. Sensing and
excitation coils can be one and the same."
sensitivity: A measure of a sensor's ability to detect small
Signals. Limited by the signal-to-noise ratio. 7
sensitivity of leak. detector: Response of a leak detector
to tracer gas leakage (typically panel meter pointer
deflection in scale divisions; leak sensitivity is measured
in units ofPa·m3·s-1 or std cm 3·s-l ) .1
sensitivity of leak test: The smallest leakage rate that an
instrument, technique or system can detect under specified conditions (implies minimum detectable leakage
rate).'
sensitivity panel: A plated metal panel with cracks of
known depth induced into the plating. Used to evaluate
and compare penetrant sensitivity.-
sensitization: Precipitation of chromium carbides in
grain boundaries of a corrosion resistant alloy,
in intergranular corrosion that would otherwise
resisted. 8
settling test: A procedure used to determine the co:nct~}i
tration of particles in a magnetic particle bath. 6
SH wave: See shear horizontal wave.
70~
shadow: A region in a test object that cannot be reached Iii
. ultrasonic energy traveling in a given direction. Caused
~ ~~ti~::~3or the presence of intervening large
j]
shadow;'~isting:
Nondestructive technique of vapor
depositing a thin metal film onto a replica at an Obliq•.. .,.
angle in order to obtain a micrograph of a test surface.f
an opaque specimen. S
••••
3
shakeout: Removing castings from a sand mold.
.,
shallow discontinuity: A discontinuity open to the surfa ~
of a solid object that possesses little depth in proportk.~
to the width of this opening. A scratch or nick may be a
shallow discontinuity in this sense. 2
shear: A force that tends to cause two contiguous parts
the same body to slide in a direction parallel to their
plane of contact. 2
shear break: Open break in metal at the periphery of
bolt, nut, rod or member at approximately a 45 degree
angle to the app.li.·.ed stress. Occurs. m._o.st often Wi:t.. ~.• .
flanged products. Also called shear crack. S,l9
shear crack: See shear break.
J
:.
l
shear horizon.talw
..ave: A shear wave.. in wh.. ich.the p.artie.If
vibration is parallel to the incidence surface. Abbre .
ated SH wave. ..
..
shear vertical wave: A shear wave in which the particle
vibration is perpendicular to the direction of wal
propagation but essentially normal to the incidence SL.J
face. Abbreviated SV wave. I
shear wave: A type of wave in which the particle motion
perpendicular to the direction of propagation. ' ,12
shear wave transducer: An angle beam transducer or
straight beam transducer designed to cause mode
verted shear waves to J?ropagate at a nominal angle
specified test medium.
•
shell core: A shell molded sand core. 3
I
shell molding: Forming a mold from thermosetting ref<~
bonded sand mixtures brought in contact with pre:
heated metal patterns, resulting in a firm shell with t
cavity corresponding to the outline of a pattern.'
!
shielding: A conducting or magnetic material placed so asc6
decrease susceptibility to interference and to increase
resolution.s
shift: A casting discontinuity caused by mismatch of
and drag or of cores and mold. 3
I
556 I NONDEStRuCTIVE TESTING OVERVIEW
shoe: A device used to adapt a straight beam transducer for
use in a specific type of testing, including angle beam or
surface wave tests and tests on curved surfaces.P See
also wedge.7
shot: A short energizing cycle in a magnetic particle test. 6.16
shot peening: Cold working the surface of a metal by
metal shot impingement. Used to clean a part surface
before inspection.i'
shoulder: Cylindrical metal component surface, machined
to receive threading indentations but in fact not
threaded, where the thread stops on the outside surface
of the pipe. s
shrink: Internal rupture occurring in castings due to contraction during cooling, usually caused by variations in
solidification rates in the mold. Includes shrinkage
sponge, small voids (stringers or bunches) or a fingerprint pattern of sernifused seams. Also applied to sur.
face shrinkage cracks. 2 ,6
shrink mark: A surface depression on a casting that sometimes occurs next to a thick section that -cools more
slowly than adjacent sections.:'
shrinkage cavities: Cavities in castings caused by lack of
sufficient molten metal as the casting cools.2,3
shrinkage cracks: Hot tears associated with shrinkage cavities.2.,3
f!Shrinkage porosity or sponge: Porous metal often with a
network of fine cracks formed during solidification of
"
molten metal, At surface, may form a localized, lacy or
honeycombed penetrant indication.f
lSI: The International Svstem of units of measurement. An
)
international system of measurement based on seven
units: meter (rn), kilogram (kg), second (s), kelvin (K),
ampere (A), candela (cd) and mole (mol). See also
MKSA.4.14
'r .•
signal: Response containing relevant information. 4.13
.~ignal electrode: Transparent conducting film on the inner
J
surface of a vidicon's faceplate and a thin photoconductive layer deposited on the mm. s
rignal processing: Acquisition, storage, analysis, alteration
I
and output of digital data through a computer."
signal-to-noise ratio: The ratio of Signal values (responses
that contain relevant information) to baseline noise values (responses that contain nonrelevant information).
See noise.4 ,7,13
simple magnifier: A microscope having a Single converg\
ing lens,"
- -
.
j
-
skim gate: A gating arrangement designed to prevent the
passage of slag and other undesirable material into the
l' casting. 3
i:~kimmer: A tool for removing scum, slag and dross from
the surface of molten metal."
-
skin: A thin outside metal layer, not formed by bonding as
in cladding or electroplating, that differs in composition, structure or other characteristic from the main
mass of metal.s
skin depth: See depth ofpenetration.
.
skin effect: The phenomena wherein the depth of penetration of electrical currents into a conductor decreases as
the frequency of the current is increased. At very high
frequencies, the current flow is restricted to an
extremely thin outer layer of the conductor. See depth
of penetration. 4.13.
.
skip distance: In angle beam tests of plate or pipe, the distance from the sound entry point to the first reflection
point on the same surface. See V-path. 7,12.
slag: A nonmetallic product resulting from the mutual dis"
solution of flux and nonmetallic impurities in smelting
.
and refining operations.I
slag inclusions: Nonmetallic solid material entrapped in
. weld metal or between weld metal and base me-tal. 2.:>
slag lines: Elongated cavities containing slag or other foreign matter in fusion welds.2.,3
.
slide: Part of a die generally arranged to move parallel to
the parting line, the inner end forming a part of the die
cavity wall and involving one or more undercuts and
sometimes including a core or cores.f
sliver: A discontinuity consisting of a very thin elongated
piece of metal attached by only one end to the parent
metal into whose surface it has been rolled.?
slurry: A free-flawing pumpable suspension of a fine solid
in a liquid. 6
.
slush casting: A casting made by pouring an alloy into a
metal mold, allowing it to remain long enough to form a
thin shell and then pouring out the remaining liquid. 3
smoothing: In image processing, use of positive coefficients in a linear combination of pixel values to
smoothen abrupt transitions in a digital image. Also
called lou; passfiltering.8
snap flask: A hinged flask removed from the mold after the
mold is made.'
Snell's law: The physical law that defines the relationship
between the angle of incidence and the angle of refraction.'
sniffer probe: See detector probe.
sniffer test: See detector probe test.
SNT-TC-IA: See ASNT Recommended Practice No.
SNT-TC-1A.
soak time: The period of time when the emulsifier remains
in contact with the liquid penetrant on the surface of the
test object. Soak time ceases when the penetrant emulsifier is quenched with water or completely removed by
water rinsing. Also Called emulsification time. 2
soaking: Prolonged holding at a selected temperature.I
soldiers: Wooden blocks or sticks used to reinforce bodies of
sand in the cope. They usually overhang the mold cavity. 3
NONDESTRUCTIVE TESTING GLOSSARY I
solidification shrinkage: The decrease in volume of a
metal during solidiflcation.2•s
solution heat treatment: A heat treatment that causes the
hardening constituent of an alloy to go into solid solution, followed by a quench to retain it temporarily in a
electromagnJ~I("
spectroradiometry: Measurement of
radiant power and spectral emittance, used particularl'
to examine colors and to measure the spectral
tance of light sources."
spectroscope: Instrument used for spectroscopy. S
I.'•
supersaturated solution state at lower temperatures.'
spectr.~scopy: spectrop.hotometry o.r spect.rora.diometIY.r.•:. ·.,.n..
solvent action: The ability of a liquid to dissolve another
which the spectrum, rather than bemg analyzed onl}.::y
materialf
a processing unit, is presented in a visible form toz e
solvent cleaning: The process of removing excess pene~",
. operator for organoleptic examination."
trant from the surface of a test object by hand wiping ';>,. spebtrum....
..'0: (!) The amplitude.distributi.?n.' of freqUe?Cie:.".•.•.·.' 1
with a solvent dampened cloth.2
a SIgnaL! (2) Representation of radiant energy m aci"
solvent developer: A developer for penetrant tests in
cent .'bands of hues in sequence according to the
.·. 'sxamelengths or frequenc.ies. A rainbow is a ,,1
which the developing powder is applied as a suspension
ene.rgy
or solution in a quick drying solvent.f
known example ofa visible spectrum."
•.••••:
solvent remover: A volatile liquid that can dissolve penespectrum response: The amplification (gain) of a receiver
trant and that is used to remove excess surface peneover a range of frequencies.'
specular: Pertaining to a. mirror-like reflective finish, as (
trant from test objects by appropriate hand Wiping
techniques.?
'
metal. Compare lambertian. s
s
source: The location where an event takes place.
specular reflection: When reflected waves and incident
source location: The computed origin of acoustic emission
waves form equal angles at the reflecting surface. S ""1
s
signals.
speed of light: The speed of all radiant energy, incIudlg
spalIing: Cracking or flaking of small particles of metal,
light, is 2.997925 x 10 8 m- S-l in vacuum (approximately
usuallyin thin layers, from the surface of an object. 2
8 000
1) "all
al th
d I
~
spalIing fatigue: See subcasefiatigue.
~'. .mi. s- . In '•.. ~.at~ri s e spee ,is ess <?.."'.'.•. •.
vanes with the material s index of refraction, wh ]
spatial resolution: Width of smallest region from which
itself varies with wavelength.8.20reliable data can be extracted."
'
speed of vision: The reciprocal of the duration of the exppspecific acoustic impedance: See acoustic impedance.
sure time required for something to be seen.8.201i!
specific examination: In certification of nondestructive
spherical wave: A wave in which points of the same ph) •
testing personnel, a written examination that addresses
f
lie on surfaces ofconcentric spheres.P.•
th e speci ications an,d products pertinent to the applicaspheroidizing: Heating and cooling to producer"~
tion. Compare general examination and practicalexamination. 8
spheroidal or globular form of carbide in steel.'
. . .• . •
specification: A set of instructions or standards invoked by
spilt gate: A gate having the sprue axis in the die parting,"
a specific customer to govern the results or perforspot Ch.eek.. tests. : Tes?ng a ~um.b.e. r .of objec~s fro~ a lot.···~.:.F.
mance of a specific set oftasks or products. s
determme the lot s quality, the sample SIze bemg clt
specimen grating: In moire and grid nondestructive testsen arbitrarily, such as five or ten percent. This does :ii6t
ing, a real grating, usually crossed lines, printed or
provide accurate assurance of the lot's quality.2
spot examination: Local examination ofwelds or castin~ 0
embossed on the surface of a specimen. It deforms with
the specimen as the specimen is loaded,"
spray scrubber: Technique ofpressure washing nonw
spectral power distribution: The radiant power per unit
soluble penetrant from the surface by introducing a hywavelength as a function of wavelength. Also J....nown
.
as
drophilic emu.lsifieror detergent. into the.;-,.ater ,;asb; .<~..
spectral energy distribution, spectral density and specsprue: (1) The channel that connects the pounng basin w.!~
tral distribution. 8
the runner. (2) Sometimes used to mean all gates, risspectral reflectance: The radiant flux reflected from a
ers, runners and similar scrap. Also called downsprue'f
3
material divided by the incident radiant flux."
downgate. .
.
.
spectral transmittance: The radiant flux passing through a
spurious echo: A general term used for any indication tl1at
medium divided by the incident radiant flux."
cannot be associated wit~ a discontinuity or bound~9'
spectrophotometer: Instrument used for spectrophotomat the location displayed,"
• !
etry. s
squid: An acronym (superconducting quantum interf&J
spectrophotometry: Measurement of electromagnetic
enoe device). A sensitive detector of magnetic fields
using a quantum effect."
radiant energy as a function of wavelength, particularly
in the ultraviolet, visible and infrared wavelengths.s
squint angle: The angle by which the ultrasonic beam
spectroradiometer: Instrument used for spectroradiomdeviates from the probe axis.'
- etry. S
squirter: See water column.
i..:.
.: '
\!.1
1.
;1
558 / NONDESTRUCTIVE TESTING OVERVIEW
standard: (1) A physical object with known material characteristics used as a basis for comparison or calibration.
(2) A concept established by authority, custom or agreement to serve as a model Orrule in the measurement of
quantity or the establishment of a practice or procedure. 7.l 2 (3) Document to control and govern practices
in an industry or application, applied on a national or
international basis and usually produced by consensus.
See also acceptance standard, working standard and
.
reference standard. 4.s.13
} standard atmospheric conditions: Atmospheric pressure
~
of 101.325 kPa (14.6959Ib rin.-2 ) . Temperature of 20 "C
(293.15 K, 68 OF or 527.67 OR). The density of dry air at
these conditions is 1.2041 kg.m-3 (0.07517Ib·ft-3).1
i standard barometric pressure at sea level: See atmospheric pressure.
·'1'\, s,tandard depth of pe~etrati,on: See,. depth, ofpenetration.
standard leak: A device that permits a tracer gas to be
introduced into a leak detector or a leak testing system
at a known rate to facilitate tune up and calibration of
the leak detector or test system.'
standard observer response curve: See eye sensitivity
'l
curt:e.
!standing wave: A wave in which the energy flux: is zero at
'.,
all points. Such waves result from the interaction of
similar waves traveling in opposite directions as when
reflected waves meet advancing waves. A particular
case is that of waves in a bodv whose thickness is an
integral multiple of half-wavelengths, as in resonance
testinz T.l0.12
Isteady 5t;':e: Thermal equilibrium, a condition of an object
wherein the temperatures throughout the object
remain constant."
jsteel: An iron alloy, usually with less than two percent carI
bon. s
Stefan-Boltzmann Law: Relationship governing the wavelength independent rate of emission of radiant energy
per unit area. The law relates the total radiation intensity to the fourth power of absolute temperature and
emissivity of the material surface. For example, intensity (heat flow) from a copper block at 100 DC (212 OF)
is 300 W·m~2 (95 BTU·ft-2·h- 1) . (Stefan-Boltzmann
constant for ~hoton emission", 1.52041 x 1015 photon·s- l·m-2 ·K-- .)9
'stepped wedge: A device used, with appropriate penetrameters on each step, for the inspection of parts having great variations in thickness or complex geometries.
The stepped wedge must be made of material radiographically similar to that being radiographed."
stereo photography: Close range photogrammetric technique involving the capture and viewing of two images
of the same object in order to reconstruct a three
dimensional image of the object."
I
straight beam: An ultrasonic wave traveling normal to the
test surface. 7,12
strain: The alteration of the shape of a material by external
forces.
stress: (1) In physics, the force in a material that resists
external forces such as tension and compression.
(2) Force per unit area,"
stress corrosion cracking: Failure by cracking under
combined action of corrosion and stress, either applied
or residual. Cracking may be either intergranular or
transgranular, depending on the metal and corrosive
medium.f
stress raiser: Contour or property change that causes local
concentration of stress."
stress relieving: Heating to a suitable temperature, holding long enough to reduce residual stresses and then
cooling slowly enough to minimize the development of
new residual stresses.'
stress riser: See stress raiser:
stringer: In wrought materials, an elongated configuration
of microconstituents or foreign material .aligned in the
direction of working. Commonly, the term is associated
with elongated oxide or sulfide inclusions in steeP
structural integrity test (SIT): A test that demonstrates
the capability of a vessel to withstand specified internal
pressure loads.'
subcase fatigue: Fatigue originating below the case depth.
Compare case crushing. See also spallingfatigue. 8
subease origin fatigue: See subcase fatigue.
.
substrate: Layer of metal underlying a coating, regardless
.
of whether the layer is base metal.P
subsurface discontinuity: Anv discontinuity that does not
extend through the surfa~e of the object in which it
exists.f See near surface discontinuity.
subsurface fatigue: Fatigue cracking that originates below
the surface. Usually associated with hard surfaced or
shot peened parts but may occur anytime subsurface
stresses exceed surface stresses."
suppression: See reject.
surface wave: See Rayleigh wave.
survey meter: A portable instrument that measures dose
rate of e;,,'"posure or radiation intensity,u
suspension: (1) A two-phase system comprising finely
divided magnetic particles dispersed in a liquid vehicle.2 (2) Liquid bath, often a petroleum distillate, in
which solid particles are suspended.v" See vehicle.
SV wave: See shear vertical wave.
sweep: The uniform and repeated movement of a spot
across the screen of the cathode ray tube to form the
horizontal baseline."
sweep delay: A delay in time of starting the sweep after the
initial pulse. Also denotes the control for adjusting the
time. 7.12
NONDESTI(UL IIVk I k;) IINU
sweep length: The length of time or distance represented
by the horizontal baseline on an A-scan.i.l2
swinging field: See multidirectional magnetization.
T
tangential field: Magnetic field at the object's surface par~
allel to thesurface. The tangential field runs uniformly
along the material/air interface and is generally weaker
than the field in the object. Measurement can be influenced by external fields. 6
tape head probe: The head of a tape recorder used as an
eddy current coil. A type of horseshoe coil."
Tarasov etching technique: Way of visually inspecting for
the presence of deleterious effects in hardened steels
by using specific etching solutions and methods of
inspection,"
temper: (1) In heat treatment, reheating hardened steel or
hardened cast iron to some temperature below the
eutectoid temperature for the purpose of decreasing
the hardness and increasing the toughness. The process
also is sometimes applied to normalized steel. (2) In
tool steels, temper is inadvisedly used to denote the carbon content. (3) In nonferrous alloys and in some ferrous alloys (steels that cannot be hardened by heat
treatment), the hardness and strength produced by
mechanical or thermal treatment or both are characterized by a certain structure, mechanical properties or
reduction in area during cold working. 3
temper brittleness: Brittleness that results when certain
steels are held within, or are cooled slowly through, a
certain range of temperature below the transformation
range. The brittleness is revealed by notched bar
impact tests at or below room temperature.P
temperature: A measure of the intensity of particle motion
in degrees Celsius (OC) or degrees Fahrenheit (OF) or,
in the absolute scale, kelvin (K) or degrees Bankine (OR), where 1 K = 1 °C = 1.8 OR '" 1.8 OF. Compare
heat. 9
temperature diagram: See time temperature transformation (TTT) diagram.
temperature envelope: The temperature range over
which a particular penetrant testing technique will
operate.f
.
tempering: Process of heating a material, particularly hardened steel, to below the austenite transformation temperature to improve ductility."
tertiary creep: Third stage of creep, marked by steady
increase in strain to the point of fracture under constant
load."
.
tesla: .The SI unit of measure for magnetic flux density
Abbreviated T. 1 T '" 10,000 gauss.6
ULV~.>I'\J'\:I
r
tes~mete. r: A magnetometer that registers field stren~.:.{.r.i~.r
m gauss (or tesla)."
::ijl~
test coil: The section of a coil assembly that excites audio;
detects the magnetic field in the material under e
tromagnetic test. 4. 13
test frequency: In electromagnetic testing, the number
complete cycles per unit time of the alternating eurrent
applied to the primary test COil. 4.13
test piece: A part subjected to testing.
v • testquaIity level: See level, rejection.
"""testS~.·.~: .~ ..ri~~ ~pecimen typical.. ly ma~e ?~ tool steel. .('0'•·.1
.• ·.•·.·
taImng.Jirtificlalsubsurface discontinuities used t08":1
uate and compare the performance and sensitivity ot
magnetic particles. 6,16
test surface: The exposed surface of a test object. 2,'i
thermal: Physical phenomenon of heat involving the
ment of molecules. Compare infrared radiation. 9
thermal conductivity vacuum gage: Instrument
operates on principle that as gas molecules are
from a system, the amount of heat transfer by conduc-
~b:oi~te.~.:;~~;e~hiS relationship is used
to
indiO)
thermal diffusivity: The speed at which heat diffuset
through an object. Expressed as the rate of temperatu"Ie
change with ti.· me and represented by ex. Each mater
has its own characteristic value for ex, combining til
overall influence of thermal conductivity, density and
specific heat. In a practical sense, thermal diffus .
determines how fast a material will heat up or c<
down. The rate of temperature change with time" IS
more. r.a.pid...in.a material with a high thermal diffUSi'?.. l.·
(e.g., metals) and slower in a material with a lower '. .•.~
fusivity (e.g., p l a s t i c s ) . 9 ,
thermal equilibrium: Condition of an object wherein
temperatures thro~ghout.the.object rem~n eonstant'l
thermography: Imagmg or VIeWIng of an object or prOCt.J~
through sensing of infrared radiation emitted by it. The
temperature patterns on the material surface produce
corresponding radiation patterns. Thus, heat flow .~
both conduction and radiation may be observed aI1fi
used to locate material discontinuities.?
three-way sort: An electromagnetic sort based on a
object signal response above or below two levels em.!lished by three or more calibration standards.v'P
threshold: See adaptive thresholding, resolution thresh! '~
and threshold l e v e l
.!
..
. . J
threshold level: The setting of an instrument that causes it
to register only those changes in response greater. nr
!
less than a specified magnitude. 4 ,13
thresholding: ])igital .data ?rocess~ng_ t~chni~ue that
reduces a gray level image into a binary Image.
throat, actual: Shortest distance from the root of a filit
weld to its face, as opposed to theoretical throatlr
weld size. 8
..
J
t \.·.'
..
hf
~~~--'---""";-------
"t.
::'!!!!;60 I
NONDESTRUCTIVE TESTING OVERVIEW
'itt:hroat, theoretical: The distance from the beginning of
the root of the weld perpendicular to the hypotenuse of
the largest right triangle that can be inscribed within
the cross sec~on of the fillet weld. Compar.e weld siz~. 8.
\throat, weld: DIstance from the root of a fillet weld to Its
.
face. Compare weld size and throat, actual. 8
~fhrottling: Reducing the net pumping speed of a pumping
system by partially closing a valve or installing a section
of pipeline with low conductance.'
through-coil method: See coil method.
~)hroughput: Quantity of gas, or total number of molecules
J at a specific temperature, passing a section of a vacuum
system per unit of time. See leakage rate. 1
"i,L,..
.
.
I
·..·..·...
·.·.•...
.· r · . ·
'.
'-
rough
.. -tr.an.smiSSi~n:. A. test. techniqu~ in which ma g-.
netic. or ultrasonic energy IS transmitted through the
test object and received by a second transducer on the
opposite side, Changes in received signal amplitude are
evaluated as indications of variations in material continuitv?
tie rod: Abar used in a casting machine to hold dies locked
'1.
against p~essure an.d, in ge.neral, also ,to serve as a way
along which the movable die platen slides.P
TIC welding: Tungsten inert gas welding.
.time base: See sweep.
e d~lay: Se sweep delay.
~e differential: See delta t.
time of flight: The time for an acoustic wave to travel
between two points. For example, the time required for
a pulse to travel from the transmitter to the receiver via
diffraction at a discontinuity edge or along the surface
I
of the test object."
.
.Jime tempera~e ~ra~sfo~ation (TTI) diagram: A
graph showing time required at any temperature to
transform austenite to pearlite, bainite or martensite.f
~p: . In casual usage, the distal or objective end of a
j borescope."
toe crack: A base metal crack at the toe of a weld. 2
joggle: The linkage in a casting machine employed to mulI tiply pressure mechanically in locking the dies. Also,
linkage used for core locking and withdrawal in a die. 3
~olerance: Permissible deviation or variation from exact
.I
dimensions or standardsf
tone burst: A wave train consisting of several cycles of the
same frequency?
1001 mark: Shallow indentation or groove made by the
. movement of manufacturing tools over a surface. Compare gouge or nick. S
·proidal field: An induced magnetic field occurring in a
I
ring test object when current is induced. See current
. induction technique. 6
t,orr: Unit of absolute pressure nearly equal to 1.33332 kPa
(1.000 mm HgV
Jrace: Line formed by an electron beam scanning from left
to right on a video screen to generate a picture."
lF
i.
7
tracer: In leak testing, a gas that is sensed as it escapes from
confinement S
.
tracer gas: A gas that can be detected by a specific leak
detector and thus disclose the presence of a leak in a
system. Also called search gas. I
tracer probe lest: A leak test in which a tracer gas is
applied by means of a probe to an accessible test surface on an evacuated test object so that the area covered by the tracer gas is localized. A leak detector in the
line to the vacuum pump enables individual leaks to be
located when they admit tracer gas.'
tracer standard leak: A standard leak in which the contained gas is a tracer gas compound.'
transducer: (1) Any device that transforms energy from one
form to another. (2) In electromagnetic testing, the test
COil,4 (3) An electroacoustical or magnetoacoustic device
containing an element for converting electrical energy
into acoustical energy and vice versa, See search unit.7.i2
transducer relative sensitivity: The response of the transducer to a given and reproducible artificial source.'
transducer, differential: A piezoelectric twin element or
dual pole transducer, the output poles of which are isolated from the case and are at a floating potential.P
transducer, flat response: A transducer whose frequency
response has no resonance within its specified frequency band (the bandwidth to --3 dB being defined),
the ratio between the upper and lower limits of its band
being typically not less than 10:5 '
transducer, resonant: A transducer that uses the mechanical amplification due to a resonant frequency (or
several close resonant frequencies) to give high sensitivity in a narrow band, typically ±10 percent of the
principal resonant frequency at the --3 dB points.'
transducer, single ended: A piezoelectric Single element
transducer, the output pole of which is isolated from
the case, the other pole being at the same potential as
the case."
transducer, wideband: A transducer that uses the mechanical amplification due to the superposition of multiple resonances to give hig.h sensitivity in several narrow
bands within a specified wide band.'
transfer function: Description of changes to the waves
arising as they propagate through the medium or, for a
transducer, the relationship between the transducer
output Signal and the physical parameters of the wave. s
transformation diagram: See time temperature transformation (TTT) diagram.
transition flow: Phenomenon that occurs when the mean
free path of gas is about equal to the cross sectional
dimension of a leak or the tube through which flow is
occurring. 1
transient heat flow: Heat flow occurring during the time it
takes an object to reach thermal equilibrium or steady
state. 9
NONDESTRUCTIVE TESTINtJ
transmission angle: The incident angle of a transmitted
ultrasonic beam. It is zero degrees when the beam is
perpendicular (normal) to the test surface.',lO
transmission characteristics: Test object characteristics
that influence the passage of ultrasonic energy, including scattering, attenuation or surface conditions.'
transmission technique: See through-transmission.
transmitter: (1) The transducer that emits ultrasonic
energy. (2) The electrical circuits that generate the signals emitted by the transducer.'
transverse wave: See shear wave.
trimming: (1) In forging or die casting, removing the parting line flash and gates by shearing. (2) In castings, the
removal of gates, risers and fins.3
troland: A unit of retinal illuminance equal to that produced by a surface whose luminance is 1 nit when the
pupil measures 1 mm". 1 nit "" 1 candela per square
meter (1 cd.m-2).8
true continuous method: Test technique in which magnetizing current is applied before application of magnetic
particles and is maintained without interruption
throughout the examination.s-"
TIT: Time temperature transformation.
tubing string: Pipe with which oil or gas has contact as it is
brought to the earth's surface. Also called production
string. s
tungsten inclusions: Inclusions in welds resulting from
solidified droplets, particles or splinters of tungsten
from welding electrodes.f
tungsten inert gas (TIG) welding: See gas tungsten arc
welding.
two-way sort: An electromagnetic sort based on a test
object signal response above or below a level established by two or more calibration standards.4 .I 3
u
U shaped coil: See horseshoe coil.
ultrasonic: Pertaining to acoustic vibration frequencies
greater than about 20 kHz.',l2
ultrasonic absorption: The damping of ultrasonic waves
as they pass through a medium.!? See attenuation coefficient. 7
ultrasonic spectroscopy: Analysis of the frequency content of an acoustic wave. Generally performed mathematicallv bv using a fast Fourier transform.'
ultrasonic "sp~ctru.n: Usually, the frequency of sound
waves ranging from 20 kHz to 10 MHz, but may extend
much higher in special applications."
ultrasonic testing: Nondestructive testing using acoustic
energy in the ultrasonic spectrum for interrogation.'
ultraviolet borescope: See borescope, ultraviolet.
l.:ILU~~Jo\I(T I
;:)0
ultraviolet radiation: (1) Electromagnetic radiation
wavelengths ranging from about 4 to about 400
between visible light and X-rays. Compare near ultraviolet radiation." (2) The range of wavelengths used fo.
fluorescent nondestructive testing is typically betweej!;;1
320 and 400 nrn. Shorter wavelengths are very haz-'''''··
ardous. Compare black light. B
ultraviolet radiometer: A meter, usually calibrated
365 nm, used in fluorescent liquid penetrant and
.
netic particle testing to measure the output of ultravio..... lefla~l?~.8
underbead. crack: A subsurface crack in the base me~tai'i'~
adjaceiJ.~ to the weld fusion zone.f
.
..
undercut: Undesirable depression or groove left unfilled
by weld. metal, creat~d by melting during ~elding
located m base material at the toe of a weld. _ . S , "
unit die: A die block that contains several cavity inserts for
.. •.•]
.,
making different kinds of die castings. 3
unsharpness, geometric: The fuzziness or lack of defini.]
tion in a radiographic image resulting from the source .
~~~~~~.~~t-to-film distance and the source-to-objeCt]
ane]t
upper confidence limit: A calculated value constructed"
- from sample data with the intention ofplacing a statistical upper boundary on a true leakage rate}
upset: A frame used to deepen either the cope or drag in
casting mold,"
UT: Ultrasonic testing.
v
V-path: In angle beam tests of plate or cylindrical sections
the path of the ultrasonic beam in the test object
point of entry on the front surface to the back surface
and reflecting to the front surface again. See also
distance. 7
vacuum: Space containing gas at a pressure below atmospheric pressure. I
vacuum box: Device used to obtain a differential pressur,j
across a weld or part of a pressure boundary that cannot"
,
be directly pressurized. 1
vacu.u~ melting: .Melting in a vacuum to prevent contar:ii
mation from au, as well as to remove gases already dit".~
solved in the metal. The solidification may also be
carried out in a vacuum or at low pressura'
vacuum pressure testing: A leak testing procedure
which the test object containing tracer gas is
within an evacuated enclosure and the tracer gas
detected after entering the enclosure. 1 Also called
jar testing.
.
.
vacuum testing: Method of testing for leaks in which
object under test is evacuated and the tracer gas
applied to the outside surface of the test object.
>,
I NONDESTRUCTIVE TESTING OVERVIEW
pressure: The pressure exerted by the vapor of a liquid when in equilibrium with the surface of the liquid.
These limiting pressures can restrict the levels of pressurization of enclosures with these tracer gases during
.
pressure leak testing.1,2
variable stt:l.ndard leak: A device that permits a tracer gas
to be introduced to the leak detector at a rate adjustable
.
by the operator. 1
vector quantity: Any physical quantity that is specified
,
with both magnitude and direction and that obeys the
parallelogram law of addition.v-"
'v hicle: A liquid medium for the suspension of magnetic
particles, often a light petroleum distillate or condi"1 tioned water. See carrierfluid. 6.16
int: A small opening in a mold for the escape of gases.3
verification test: Tests intended to confirm the capability
of the type A leak test method and equipment to determine the containment leakage rate.'
vertical limit: The readable level of vertical indication on
an A-scan.'
• ,rticallinearity: See linearity, amplitude.
video: Pertaining to the transmission and display of images
"'1 in an .electronic format that can be displayed on a
1
"'1
screen.f
video presentation: An electronic screen presentation in
1 wl1i.ch.. radiofrequency Sign.als..h.ave been rectified and
J usually filtered.'·l2
H(leoscope: Jargon for video borescope''
yi,mcon tube: Television tube that uses the photoconduction method. Compare image ~rthicon. 8. ..
.
.~lgilance decrement: Degradation of reliability dunng
performance of visual activities over a period of time.
t See also psychophysics. 8
jrtual grating: In moire and grid nondestructive testing,
closely spaced walls (or planes) of light separated by
darkness, created by the alternating constructive and
destructive interference of two intersecting beams of
coherent light. 9
virtual leak: Emission of vapors within a vacuum system
that result from condensible or trapped vapors. They
, gradually evaporate from surfaces or escape from pockets raising the absolute pressure in the same manner as
a real leak. 1
'~cous flow: The flow of gas or gas mixtures through a leak
or duct under conditions such that the mean free path is
smaller than the cross section of the leak or opening.
Viscous flow may be either laminar or turbulent and is
most likely to occur during leak tests at atmospheric or
higher pressures. With vacuum conditions, the flow of
tracer gases to the leak detector element is usually by
diffusion, resulting in slow response to leaks being
probed by a tracer jet. l
I.
I
visibility: The quality or state of being perceivable by the
eye, In many outdoor applications, visibilityis defined in
terms of the distance at which an object can be just perceived by the eye. In indoor applications it usually is
defined in terms of the contrast or size of a standard test
object, observed under standardized viewing conditions,
having the same threshold as the given object. 8.2o
visible light: Radiant energy generated in the 400 to
700 nm wavelength range. 6 ,16
vision: Perception by eyesight, See far vision, machine
vision, mesopic vision, near vision, peripheral vision,
photopic vision, scotopic vision and speed ofvision, 8
vision acuity: The ability to distinguish fine details visually.
Quantitatively, it is the reciprocal of the minimum
angular separation in minutes of two lines of width subtending one minute of arc when the lines are just
resolvable as separate. 8,20
visual acuity: See vision acuity.
visual angle: The angle subtended by an object or detail at
the point of observation. It usually is measured in minutes of arc. B•20
visual background noise: Formations on or signals from a
test object that constitutes the background to a discontinuity. The higher the level of visual background noise,
the more difficult it is to distinguish a discontinuity"
visual efficiency: Reliability of a visual system. The term
visual efficiency uses 20/20 near vision acuity as a baseline for 100 percent visual efficiency.s
visual field: The locus of objects or points in space that can
be perceived when the head and eyes are kept fixed.
The field may be monocular or binocular. 8.2o
visual perception: The interpretation of impressions
transmitted from the retina to the brain in terms of
information about a physical world displayed before the
eye. Visual perception involves anyone or more of the
following: recognition of the presence of something
(object, aperture or medium); identifying it; locating it
in space; noting its relation to other things; identifying
its movement, color, brightness Or form.B,zo
visual performance: The quantitative assessment of the
performance of a visual task, taking into consideration
speed and accuracy.8.20
visual purple: Chromoprotein called rhodopsin, the photosensitive pigment of rod vision. The mechanism of
converting light energy into nerve impulses is a photochemical process in the retina. Chromoprotein is transformed by theaction of radiant energy into a succession
of products, finally yielding the protein called opsin
plus the carotenoid known as retinene. B
visual task: The appearance and immediate background of
those details and objects that must be seen for the performance of a given activity. The term visual task is a
misnomer because it refers to the visual display itself
and not the task of extracting information from it.8.20
NONDESTRUCTIVE TESTING GLOSSARY I
visual testing: Method of nondestructive testing using
electromagnetic radiation at visible frequenoies."
voids: Hollow-spots, depressions or cavities. See also discontinuity and dislocation. S
VT: Visual and optical testing.
w
wea~, frettin~: Surface degradati.·on c.aused .by microwe~(.~i~
mg and microfractures on surfaces rubbmg each othl,,;iHI
Also called chafing, friction oxidation and wear oxida·
tion. See also cocoa and false brtnelling, 8
wedge: A device used to direct ultrasonic energy into a
object at an acute angle.12 See also shoe. 7
weld bead: A deposit of filler metal from a Single weldif,}~
pass.?
wash: A coating applied to the face of a mold prior to cast- _. weld crack: A crack in weld metal.f
1.'n-0'
O' 3
':'-;o;.we1<\...line: The junction of the weld metal and the
water break free: Rinse water, having the ability to cover .'
me~aLor the junction of base metal parts when
an entire surface in an unbroken film.2
me.tiil"is·not used. 2
water break test: A quality control test for conditioned
weld metal: That portion of a weld that has been melted
2
water. Verifies that the water's surface tension has been
during welding.
sufficiently reduced by a wetting agent to satisfactorily
weld nugget: The weld metal in spot, seam or projecti!
cover test objects and disperse magnetic particles. May
welding. 2
."
also be used to establish surface cleanliness before
weld size: Thickness of weld metal - in a fillet weld
testing. 6
-~stanc~ from the root to ~he t~e of ~he largest iso~cei
water column: A tube filled with water and attached to the
nght tnangle that can be inscribed III a cross section u
front of a transducer to couple an ultrasonic beam to a
the weld. s
., ,_.
test object. A delay line between the initial pulse and
weld throat: See throat,
the front surface signal. Also serves as a coupling
w~lder's flash: Clinical condition, specifically keratocc... 1
device. See also delay line. 7
junctivitis, commonly caused by overexposure to ultrawater jet: An unsupported stream of water carrying ultraviolet radiation of welding a r c , s " ' 1
sonic signals between the transducer and the test object
wet developer: A developer in which the developing pojr
surface, Also called a squirter: 7
der is applied as a suspension or solution in a liquid,
water line: A tube or other passage through which water is
usuallv
water or solvent.t
circulated to cool a casting die. 3
wet method: A testing technique in which magnetic par ]water path: In immersion testing or with a water column,
eles are applied as a suspension in a liquid vehicle. 6 ,lf..
the distance from the transducer face to the test object's
wet slurry technique: A magnetic particle test in whiSP
front surface.7,l2
6
t.he parti:les. are susp._~. .~. d.-ed.in hl.~.gh.viSC. osity
.. vehicle. !J
water tolerance: The amount of water that a penetrant or
wetting action: The ability of a hqUld to spontaneou"'if
emulsifier can absorb before its effectiveness is
spread over and adhere to solid surfaces. 2 ··
impaired.?
wetting agent: A substance that increases wetting acti •.
wave interference: The production of a series of maxima
by-reducing the surface tension of a liquid, there..
and minima of sound pressure as a consequence of the
7 12
reducing the formation of air bubbles. 2
superposition of waves having different phases. .
wheel transducer: A device that couples ultrason'e
wave train: A series of waves or groups of waves passing
energy to a test o.b~ect th~ou?h the rolling contact arJ
along the same course at regular intervals."
of a wheel contammg a liquid and one or more trarrswavefront: In a wave disturbance, the locus of points havducers. 7•12
.ing the same phase.7.l2
.white light: Light combining all frequencies in the
wavelength: The distance needed in the propagation direcspectrum.f
tion for a wave to go through a complete cycle. 7.l O
Wien's Displacement Law: For practical infrared imagweak sand: Refers to sand that will not hold together when
ing, Wien's Displacement Law gives the wavelength f
used to make a mold.'
maximum emittance. 9
1
wear: See erosion; rats tooth principle; wear, adhesive; and
wobble: In electromagnetic testing, an effect that produc~~
wear,fretting.
variations in an output Signal ofa test system andarisp.f
wear face: A protective material on the face of a transducer
from variations in coil spacing due to lateral motion.,
to prevent wear of the piezoelectric element.i-P
the test object in passing through an encircling coi1. 4 , J
wear oxidation: See wear, fretting,
wear, adhesive: Degradation of a surface because of
work hardening: Increase in hardness accompanyip~
microwelding and consequent fracture due to the slidplastic deformation of a metal, Usually caused inll
metal by repeated bending or flexing. Compare ere! ii,
ing of one surface against another. Types include fretand recovery. S
ting, galling and scuffing.S
l'
tobi
I'
t
t .:
f
~----------------------------"1":~
564 I NONDESTRUCTIVE TESTING OVERVIEW
working standard: Work piece or energy source calibrated
and used in place of expensive reference standards. In
the calibrating of photometers, the standard would be a
light source.f
worm holes: Elongated or tubular cavities due to
entrapped gas. Also called pipes.2
wrap around: The display of misleading ultrasonic reflections from a previously transmitted pulse due to the use
of excessive pulse repetition frequency.21 See ghost. 7
y
yoke: A U shaped magnet that induces a field in the area of
the test object that lies between its poles (magnetic particle or flux leakage testing). Yokes may be permanent
magnets, alternating current electromagnets or direct
current electromagnets. 4•6 .l 3
x
z
X-ray: Penetrating electromagnetic radiation emitted when
the inner orbital electrons of an atom are excited and
release energy. Radiation is nonisotopie in origin and is
generated by bombarding a metallic target with high
speed electrons.'!
zircon sand: A highly absorptive material used as a blocking or masking medium for drilled holes, slots and
highly irregular geometries to reduce scattering during
radiography.3
NONDESTRUCTIVE TESTING GLOSSARY I
REFERENCES
1. Nondestructive Testing Handbook, second edition: .,
VoL 1, Leak Testing. Columbus, OR: American Soci- ..'1f",
ety for Nondestructive Testing (1982).
.
2. Nondestructive Testing Handbook, second edition:
Vol. 2, Liquid Penetrant Tests. Columbus, OR: American Society for Nondestructive Testing (1982).
3. Nondestructive Testing Handbook, second edition:
Vol. 3, Radiography and Radiation Testing. Columbus, OR: American Society for Nondestructive Testing (1985).
-'
. ,.
4. Nondestructive Testing Handbook, second edition;
Vol. 4, Electromagnetic Testing. Columbus, OR:
American Society for Nondestructive Testing (1986).
5. Nondestructive Testing Handbook, second edition:
Vol. 5, Acoustic Emission Testing. Columbus, OR:
American Society for Nondestructive Testing (l987).
6. Nondestructive Testing Handbook, second edition:
Vol. 6, Magnetic Particle Testing. Columbus, OR:
American Society [or Nondestructive Testing (1989).
7. Nondestructive Testing Handbook, second' edition:
Vol. 7, Ultrasonic Testing. Columbus, OR: American
Society for Nondestructive Testing (l991).
8. Nondestructive Testing Handbook, second edition:
Vol. 8, Visual and Optical Testing. Columbus, OR:
American Society for Nondestructive Testing (1993).
9. Nondestructive Testing Handbook, second edition:
VoL 9, Special Nondestructive Testing Methods.
Columbus, OH: American Society for Nondestructive Testing (l995).
-'
10. Weismantel, E. "Glossary of Terms Frequently Used
in Nondestructive Testing." Materials Evaluation.
VoL 33, No.4. Columbus, OR: American Society for
Nondestructive Testing (1975).
11. NDT Terminology. Wilmington, DE: E.!. du Pont de
Nemours & Company, Photo Products Department
(n.d.),
12. Nondestructive Testing Methods.
T033B-1-1
(NAVAIR 01-1A-16) TM43·0103. Washington, DC:
Department of Defense United States Air Force
(June 1984): p 1.25.
13. E 268-81, DefinitiOns Approved for Use by Agencies
of the Department of Defense as Part of Federal Test
Method Standard No. 151b and for Listing in the
DoD Index of Specifications and Standards. Philadelphia, PA: American Society for Testing and Materials
(1981).
14. IEEE Standard Dictionary ofElectricaland Electronic
. • Terms. New York, NY: Institute of Electrical and Llt:\.,-.;~~
,-. tronics Engineers (distributed by Wiley-Interscience,
Qj\.iSion of John Wiley and Sons) (1984).
15. Glossary of Terms Used in Nondestructive Testing,
Part. 2. London, United Kingdom: British Standardsl
.• •.i
Institute (November 1 9 8 4 ) . . :
16, E 269-89, Standard Definitions of Terms Relating to .
Ma..gn.~tl.·C Par:icle Exam.~na.tion .. Phila~.elphia, ~A]
. . •. •.
American SOCiety for Testmg and Matenals (1989" .)
Ii. API RP5A5, Recommended Practicefor Field Inspec- .
tio.n ofN
.. e~ Casir!g,i:I1.ubin g and Pl~i~~nd Drill PiPe)
. .•. . . .
third edition. Washmgton, DC: American Petroleurr.
Institute (1987).
"1
18. "Ultrasonic Flaw Detection." The Glossary of Terms
.·.
used. in Nondestructiv.·e Testing. British StandarcI .·•.1
3683, Part 4. London, England: British Standard~'il
Institute (1985).
.
19. E. PRI. Le
.• , aming M.odu.les. Charlo.tte, NC.;. Electric.. ,.,~•,.
Power Research Institute (various y e a r s ) ' j
20. IES Lighting Handbook: Reference Volume. New';
York, NY: Illuminating Engineering Society of North
"
America (1984).
21. MIL-STD-371, Glossary of Terms and Definitionsfol"j
Ultrasonic Testing Procedures. Washington, DC
(Department of Defense): United States Army~
(October 1987).
'~
22. 1992 Annual Book of ASTM Standards. Section 3';"
Metals Test Methods and Analytical Procedures:
VoL 03.03, Nondestructive Testing. Philadelphia, PA
American Society for Testing andMaterials (1992).
23. E 1316, Standard Terminology for Nondestructive
Examinations. Philadelphia, PA; The American
ety [or Testing and Materials (1993).
24. E 500-85, Standard Definitions of Terms Relating
Ultrasonic !es.tin g.. Philadelphi.a, ~A: .American SOCi.-•. •. '.',.'1
ety for Testing and Materials (1980).
..'j
25. Mish, Frederick C., ed, Webster's Ninth New Colle~A
giate Dictionary. Springfield, MA: Merriam-Webster
(1984).
26. "Nondestructive Inspection and Quality ControLJ
Metals Handbook, Vol. 11. Metals Park, OR: American Society for Metals (1976).
27. ANSIIANS-58.6. New York, NY: American Nafirms.
Standards Institute (1981).
INDEX I 567
INDEX
A
Aboveground storage tanks, leak testing .. , " ,
',.... 65-69
Absolute eddy current transducers , , , , , . , ' . , . ,
,
,. 203-204
Absolute pressure "
' .,,,,
' , . , ., . . .
.,
, . .. 20
Absorption, of radiation .. , . , . ,
, .. , , , .. ' 95-98. 144-146
Accessibility limitations, on methods '
' , ... ,
13
Accident prevention ." ..... ' .. ' , . ,
... , , ... ' , , . .. 5
Accumulation method, of helium leak testing .',.""....
60
Accuracy specification
, . ' ... , . ' , , .. , . . .
. ..... ' 12-14
ACGIH. See American Conference of Gcvcmmentnl Industrial Hygienists
Acid pickling cracks "."..
. . , , ..... ' , . , , .
264-26.'5
Acoustically active/passive leaks ..... , .. , ,
. , ... ' . . .. 61
Acoustic emission ..... ' . , . , , , .. , .
. .. , . . . . . .. 298
304, 316-317
felicity effect .. , , . , . . . .
Kaiser cffed
,,...
302-303. 304
sensors ."
"" .. ,.
. , , . ' , , , , .. , .
62-64, 301
Acoustic emission testing ., , . , ..... , . , . . .
297-344
advantages " " " " " " "
.... , , ". 299-300
applications . ' . , , . . . . .
, , ... , . . .
, ' , . ' .' 300
bucket truck/lilt inspection , . ' , , , '. ..
302. 305·309
fiber-reinforced plastic inspection ... , .... ' """"
310-317
gas trailer tubing
, . , . , ..... ' , . , . , , .
. , . , , ... 318-321
resistance spot welds " " " " ' "
..... , , , . .. 323-330
undersea electronic repeaters
331-336
computer application " .... , , , , .. , ,
.,,.,
' , , . . .. 302
data interpretation """"
... ,
,,.
303-304
equipment for. . . .
, , , , . , , , , . . . . . . , , , , , ...301-302
frequency selection for
,,...
.
,
,.,,.
301-302
sensitivity , . , , . . . . . . .
.,,,.,,
, . , . , . , .. '"
303
standards .. , " " " " " " " " " ' " .... "", .... ".... 299
Acoustic leak testing. , . . .
61-64.300
multiple acoustic emission sensors "',.".
..,
, . ' ,. 62-64
ultrasonic detection
,.".,....
,
, , , , . .. 61-62
Acoustic nondestructive testing methods ... , .
. 16. 505-506
See also Acoustic emission testing; Sonic-ultrasonic; Ultrasonic testing
Acoustoultrasonic testing . . . . . .
, . , . , , .... , . , . , . , . .. 476. 506
Acquired color vision deficiencies ' ... , . . . . .
. .. , ... , , 433
Action spectra .. . .. .. . .. . .. .. .. '"
" " " ' " ' ' ' ' ' ' ' ' ' ' . 437
Active infrared thermography
" .. , .... , , ... ,. .", 482. 484
Additional leakage technique " " " , . , .
. , , , . , .. ' ., 51-52
Aerial surveys '
,... " .,,,.,..........
. 492
Air coupled ultrasonic transducers, . , .. ' , , , . , . . . .
371-372
Aircraft
bolt hole eddy current testing ...
. .. , ... , . ' . ' , , , , . . .
231
propeller blades, borescope inspection
... , , , .. ,. 452
rotor wheels. immersion ultrasonic testing of
... , . , , ,. 414418
tires, shearographic testing
",.,
' .. ,,'..... ". 500
Alloyidentification
,.",
,
,...
474.475.503,504
Aloha Airlines, fatigue crack incident involving "
, 3
Alpha particles
,. .. .
"",'.,
,........ ..,. , 93
Alternating current ... ",................ ., . , , , . , , . . .. 281
Alternating current demagnetization .,.,', .. ,
' ,. 286
'.',1;.
Aluminum
aircraft rotor wheels. immersion ultrasonic testing. , .. , ... , .. 414-41S
Bllols, eddy current testing
",
,
,......... :2 L4
alloYs;pltr.asonic testing; .. ,. ,
,
"
"
,. 411
bolt holeS, eddy current testing
, .. ,
,
".. 229. 231
radiogr1ipqy ,.'. , ,
~. ,
145. 146. 150, 153, 169
thermogniphy
, . , .. , .. ,
, , . . . . . . . . . .. 495-496
tube walls, remote field eddy current testing of . . . . .. ,
211
ultrasonic beam attenuation by .',
,
"
,
,. 392
ultrasonic testing .. ,.,.,
,
,.,.'"
'
,. 362. 411
American Confe;ence of Governmental Industrial Hygienists
(ACGIH) ,....
' ... ' . , ..... '. .
"
,........ 437
visual safety recommendations. ..,.,.,."
,
, .. ,..... 439
American National Standards Institute (A.""'SI)
, . 2fJfJ
ANSIIASNT CP-189-1991 ,'
'., . , .. ,
,
80
ANSI Types 1 and 2 radiographic e"'P0sure devices
. ..
ANSI Z136,l-1993 .. , , ,. ".,......
,,
, , . , .. , . ,..
American Petroleum Institute (API)
.,,
,
299
API 575
' . . . . . .. . .. "
,'."
'
.
API 620 . , , .
' ,
' . , , .. , .
' . . . . . . . . .. .
,."
API 650 . .
,,.,
,.
. . . . . . .. .
,
.
API 6.51 ' . , .
, , ., '.'",.... ..,' .. ,."
.
API 652 . . .
..'.,.....
',,.,,
,
,
,
'
API 653 ' ,
,,,
, .. ' , . ,
,,
,.,,.,, .
American Society for Testing and Materials (ASTM), ,
.
,", , , . ,
acoustic emission testing standards .. ".".,.,
"",.'"
"
",
.
ASTM D 4788
ASTM E 380 ., .. ,.,.,
" .. ".,.,.,
,
, .
ASTM E 427 .. , , . . . .. .' .. ,., .. ,.,.,.,. .
"." .. " ..
ASTM E 1476. ..,
, .. , .. ,
" .. "
'
,. .. 503
ASTM E 799 blower doors
,." .. ,.,
,
' .. , ,
,
,
,
ASTM E 747 penetrameter
ASTM F 914 ' , , , , . ,
,
,,,.,
,,
307
ASTM plaque penetrameter " .. ,
, .. ,'...... " 166·167. 169
Amertean Society of Mechanical Engineers (ASME). ,
299
ASME Boiler and Pressure Vessel Code ' . , , .. ,
, .. , 4411
American Society for Nondestructive Testing (ASl\i'T) , , .. 2, 80, 299 ,,~
ANSIIASNT CP·189·1991 ., .. , ... ,. ... . , .. , . , . , , ... SO. 299
ASNT Recommended Practice No, SNT-TC-1A . , , ..... 40-41,80,
Ammonia sensitive paint leak testing
.,,.,,.,
.
Amplitude gating '"
,...
. .. , . , .. , . ,
,,,
Angle beam contact ultrasonic testing " .. ,.... 353, 354. 355. 357
for weld testing
,
,
"".,.. 397-399.
Angulated boreseopes "
", , . " ' . , .. , , , . .. ..",
.
Anisotropic materials, ultrasonic wave propagation in , .
Annular eddy current transducers
,
" .. ,..... ,.
Anode, X-ray tubes
, .. . .. ",
"
,
.
Anode grounded circuit, X-ray generators
,,,.,,
, ...
Anomaly location
thermography ,
,.",
',."
, . " " " . 478
Xvray computed tomography .. ;............. ,.' ..... , 195,
See also Discontinuity detection
ANSI. See American National Standards Institute (ANSI)
Aperture
.. .. .. .. 446
568 I INDEX
Appearance specifications
, . . .. . .. 30
Archival stor~ge, of radiographs
1il
Array eddy current transducers . . . . . . . . . . . . . . . . . . . . . . . . . .. 203
A-scan presentation, ultrasonic testing .. 356-358,380,381,392.395
ASNT. See American Society for Nondestructive Testing (ASNT)
429
Astigmatism
ASTM. See American Society for Testing and Materials (ASTM)
Atmospheric pressure
54, 55
Atmospheric pressure vessels, acoustic emission testing. .. 311, 313
Atomic number, dependence of photon absorption on
97-98
Attenuation coefficients, radiation absorption- . . . . . . . . . . . .. 95, 98
Automated bolt hole inspection . . . . . . . . . . . . . . . . . . . . . . . . . .. 231
Automatic bar inspection systems
, 218-222
Automobiles and components
6
borescope application
.
"
452
eddy current testing
200, 232-238
thermography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..
492-493
Autonomous submarines . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
46.5
Autoscan techniques, for bolt hole inspection
228
Aviation industry, boreseope applica.ti~n
452
See also Aircraft
232-234
AUe shafts (automotive), eddy current testing '"
B
Back lighting
469
Backscatter/absorption gas imaging (BAGI) leak testing . . . .. 39-40
Backscattcred radiation
,
. .. 146, 147
Back surface reflections
368,38.5.410
BaIl bearings, magnetic flux leakage testing .. ..' . . . . . . .. 245
Bandpass optical filters . . . . . . . . . . . . . . . . . . . . . . . . . .. .... 470
Bar inspection systems
. . . . . . . . . . . . . . . .. .. .
218-222
Barium day. . . . . . . . . . . . . . . . . ..
.
148
Barium platinocyanide
.
174
Barkhausen effect
,................. 298, 504-505
Barkhausen noise analysis
.. .. .. .. . ..
505
Bar magnets
267.271
Beam focusing, X-ray tubes . . . . . . . . . . . . . . . . . . . . . . . . . .. 100-101
Bell jar method, of helium leak testing. . . . . . . .
. . . . . . .. 60
Berry resistance strain gage
,
506
Beta particles . . . . . . . . . . . . . . . . . . . . . . .
.
93
Beta ray thickness gages . . ..
13
Betatrons
106,107-108
Billet inspection system
222-223
Billets
222-227
eddy current testing of steel. . . . . . . . . .. ..
magnetic particle testing of steel. . . . . . . . . . . . . . . . . . . . . . . . . . .. 259
.
481-482
Blackbody radiation
Black light radiometers . . ..
. . . . . . . . . .. 437
Blind spot ...
.. .. . .. .. .. .. .. .. .. .. . .. . .. . .. .. ..
430
Blooms...........
.
259
Blowholes
260
Blue hazard
439
Boilers, failure
,.
. . . . . . . . . . . . . .. . .. ,............. 4
Boiler tubes, visual testing
, , . . . . . . . . . . . . . . . 453, 461
Bolt hole inspection (eddy current)
228·231
Bolt hole probes
, ,..............
.
230,231
Bonded materials/structures, thermography . . . . . . . . . . . . . 493495
See also Composites
Bonding
. . . . . . . . . . .. .
44-45
Bond testing ... ' .. ,............................... 364, 369
composites, using immersion ultrasonic testing
423
Boot attachment, for immersion ultrasonic testing
Borescopes
,
applications
, .................... .
, .. 410
, 449-452
, 452-453
construction
, .. ,................................ 454-455
,....... 441
diopter adjustment
optical systems for
,
,............... 453-454
photography with
455-456
video application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 459-461, 466
Bouwers/Schmidt lenses .,.
182
Bragg angle
93
various crystals
94
Brake cylinders (automotive), eddy current testing
234-235
Brazed Joints. See Joints
Bridge surfaces, thermography
492
Brightness
21, 441
Brittle coating method
,................... 507
Bssean presentation, ultrasonic testing .. 356,358-359,380,381,395
Bubble leak testing. .
40,57-58
bubble equivalents
,..... .. . .. ,
41
liquid HIm technique
.
,
57-58
liquids for
,'.................................... 57
sensitivity
. . . . . . . . . . . ..
31-32
vacuum box technique
58, 66-67
Bubblers, for immersion ultrasonic testing .. ,.......... 408-409
Bucket truck/lift inspection, using .acoustic emission " 302, 305-309
Buffer rods
,,
,
, . . . .. 401
Buildings, thermography
.. ,
'
490-491
Bunsen-Roscoe reciprocity law
140-141
c
Cadmium zinc sulfate
,..
.
, 174,176
Calcium tungstate
..........
174
Calibratedborescopes . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. 452
Calibrated physical leaks.
.
, . . . . . .. 49
CaIifornium-252.
.,. . . . . . . . . . . . . . . . .. 98
Cameras
..
'" 446
See also Television systems
Camshaft heat treat inspection
'.
.
237-238
Cannon tubes, magnetic flux leakage testing . . . . . . ..
244
Cars. See Automobiles and components
Case depth, of automotive parts, by eddy current
testing. . . . . . . . . . . . . . . . . .
.
, 232-234.236-237
Castings
263
discontinuities .,...........
improving prod uct design through nondestructive testing . . . . . . . . .. 5
191
internal evaluation by X-ray computed tomography
Cathode, X-ray tubes . . . . . . . . . . . . ..
.
, 99
Cathode grounded eireuit, X-ray generators
104
Cathode ray tubes
, . . . . .. . . . . . . . . . . . . . . . . . . .. 462-463
Ceiling fixtures .
..
440
Center grounded circuit, X-ray generators
104
Ceramic capacitor acoustic emission crack detector
332-334
Ceramic ultrasonic transducers
..
372
Cesium-137 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 115, 118-119, 145
Cesium iodide
,..... ,
174, 176-177
Channel electron multipliers
177
Characteristic curves, radiographic films
,
, 161-163
Charge coupled devices
179, 180
radioscopy application
visual testing application
, 459, 466, 471
Charge injected devices
471
INDEX I
Chemical composition/analysis
" 16, 17
Chemical industry, borescope application
453
Chief inspector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 12
Circular magnetic fields
270
Circumferential eddy current transducers "
204
Circumferential magnetization
, 273-274
Cleaning, for liquid penetrant process
86-87
Cleanliness, importance in visual testing
440
Cobalt·GO
114·116, 117, 145
Coercive force . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . .. 278. 288-289
Coherent photon scattering
95, 96, 97
Coils, for magnetic flux leakage testing . . . . . . . . . . . . . . . .. 246-247
Cold headed pinion gear eddy current testing . . . . . . . .. . 235-236
Cold shuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 263
Collimators, radiographic use . . . . . . . ..
122. 123
Color chip . . . . . . . . . . . . . . .. ... . . . . . . . . . . . . . . . . . . . . . .. 459
Color temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 434
Color vision
432-434
Color vision deficiencies (color blindness)
432-433
Comparators . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . .. 444
Complex structure evaluation, by X-ray computed
tomography. . . . . . . .
....................
188. 190-192
Composites
. . . . . . . . . . . . . . . . . .. ... 298, 300
acoustic emission testing
acoustoultrasonic testing
. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 506
anisotropy
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 349
discontinuities . . . . . . .
.
419, 420-423
immersion ultrasonic testing. . . . . . . . . .. .
419-423
tap testing . . . . . . . . . . . . . .. .
. . . . . . . . . . . . . .. .
505
thermography . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . .. 486-489
ultrasonic beam attenuation by . . ..
392-393
ultrasonic pulse echo testing. . . . . . . .. 383-384, 386·388. 393-394, 395
Composite vessels, acoustic emission testing,
310·311
Composition. See Material composition
Compressed gas cylinders. . . . . . . . . . . . . . . ..
47
Compressibility
.. 50
Compton scattering
,...................
95. 96-97
Computed tomog-raphy. See X-ray computed tomography
Computers
acoustic emission testing application
302
component reliability. . . . . . . . .
. . . . . ..
6
Concealed cut (composite discontinuity) .. . . . . . . . . . . . . . . . .. 421
Conduction heat transfer . . . . . . . .
. . . . . . . . . . . . . .. . 478·479
Conductivity units
. . . . . . . . . . . . . . . . . .. .
21
Cone beam computed tomography.
.
190
Cones (eye) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . '" 429
Contact pulse echo ultrasonic testing. See Ultrasonic pulse echo testing
Contact thickness gaging
369
Continuous image averaging
. . .. 185
Continuous test method, of magnetic particle testing . . . . . . . .. 292
Continuous X-radiation . . . . . . . ..
93
Contrast, radiographic images
142, 148-149, 164-165
Contrast sensitivity, in X-ray computed tomography . . . . .. 193, 195
Contrast stretching radioscopic image enhancement
187
Control, role of nondestructive testing in quality,
,......... 5
478
Convection heat transfer
Conventional holography
498
Cooling cracks. . . . . . .. . .. ,
,.. .
261-262
Cornea
429
Comer cracking
"
264
Corrosion
266
eddy current testing
200-201
Cosmic rays
92
Countered shoes
,.. 4Coupling media, for ultrasonic pulse echo testing
400-4\
Crack detection
"............................... 2
acoustic emission testing
, . .. 298, 332.- ..A
in automotive parts, by eddy current testing
232, 233, 234in bolt holes, by eddy current testing
, 228, 229·230..
leak testing
,........................ 23
liquid penetrant testing
78
magnetic flux leakage testing
242. 245-246, 25~"25311
point triangulation profilometry . .
,..... 501-.502[1'1
potential drop method .'
,. 503 'A,
~::~~fit~sti~~· :::::::::::::::::::: ::::::::::.::::::::
various-methods . . . . . . . . . . . . . . . . . . . . . . . . ..
16.
visual-tespng
,
,
.
See also Leaks
Cracks
,.
Crater cracks
.
Cross section, for neutron absorption
.
Cruise missile engine, internal e~aluation by X-ray
computed tomography
, . . .. 19 L
Crystals, Bragg angle
,....... .
, .
C-scan presentation, in ultrasonic testing .... 356,359.380-381.
CT. See X-ray computed tomography
Cup core eddy current probes
,,
.
Cupping
,
.
Curie point .. . . . . . .. .
,
Curie point heating
, . . . 2b4.1S~.
1
. ]
Cyclotrons
.
106·107, 108
~;~:;:~cS~ti~f~cti~n,.~~~u~~~. ~r.~~~~ .n~~do~~~~~~~.t.e.s~.~ 28
D
Dead zone..............
.
Dees
Defects. See Discontinuities
Definition, radiographic images
Deformation measurement
:0.~l~t:~ ~e:o~~tion
-
.
.
.
497-498
D;;:
.. ..
.. . .. .. .. . .. .. .. . . .... 42]
Delaminations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 419. 420. 487
Delay lines . . . . .. .. . . . . . . . . . . . . .. . . . . . . . . . .. 354. 381. 40L
Demagnetization
258, 269.282, 284-281
~:;;:::7:::'~.:::::::::.. ::::::::::::::: ::::::::::::::: ~6)
Depth of penetration, eddy currents. . . . . . . . . . .. 202, 204-205,
Derived 51 units . . . . . . . . . . . . . . . . . .. .
.
Design engineer
.
Detector probe technique, leak testing
,.
Developers, for penetrant testing. . . . . .. .
77.
Diamagnetic materials
.
Diaphragms, radiographic
. . . . . . . . . . . . . . . . . . . . . . .. 148,
Die forgings
411
Diesel engine pistons, eddy current testing . . . . . . . . . . . . . .
~?
Differential eddy current transducers
203.201
Differential pressure
,
,............
Differentiation, in vision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 428
Digital image enhancement matrix
,.
Dimensions
" 16,
Direct coupled zone
..
.
Direct current. . . . . . . . . . . . .. .
281-283
2",1
570 I INDEX
iUii1lDi:re()t current demagnetization . . . . . . . . . . . . . . . . . . . . . . . . . .. 286
;~~Di:rej~t vision borescopes . . . . . . . . . . .
.................
45.5
Discontinuities
, 259-266, 475
acoustic emission signatures
. . . . . . . . . . . . . . . . . . . .. . .....316
composites '"
' 419.420423
grain size
.
413-414
subsurface
, 271
thermal diffusivity
,
479-480
• iscontinuity detection .. . .. .. .. .. . .. . . .. .. .. .. .
.... 2
• acoustic emission testing. . . . . . . . . . . . . . .
. 298, 314-315. 318-321
composites, by thermography . . . . . . . . . . . . . . . . . . . . . . .. 486-489
composite tubing
420·422
eddy current testing
200.202.218-219,220,222
failure and . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 4
infrared thermography. . . . . . . . . . . .
.
, .. " 48.5
liquid penetrant testing .
77-78
magnetic flux leakage testing ..
242. 245-246. 2.'50-253
magnetic particle testing . . . . . . . . . . . . . . . .
258-266
potential drop method . . . . .
503
shearography . . . . . . . . . . . . . . . . . .
. . . . . . . . . .. 500
ultrasonic testing . .
..........
347. 352, 354. 365, 369
immersion technique. . . . . . . . . . . . . . . .
410-414
straight beam pulse echo technique .
. . . . . 31)4-31)1), 394-395
various methods . . . . . . . .
16. 17
visual testing .. . . . . . . . .
. . . . . . . . .. 452. 463-464
See also Crack detection
Dosimeters .......
. .......
112. 127
., ......... 6.'5-68
oUble.. bott•.om stor~ge tan~s, leak .testing
ry powder magnetic particles
.
., 289. 290-291
82
'..~' ry powder penetrant developers .. ,
.
. .... 81
Dual mode penetrants
.
... 304
'~Junegan corollary, to the Kaiser effect
ynamic leak testing
.
.
36.37
ynamie method, of helium leak testing
.... 60
Dynamic response
.
16.17
.
r
T,
"J.•
'C
l)arth's magnetic field
267. 268-269
.
.. .. 21)7
1and demagnetization process
.
,.l.core eddy current probes . , . .
.
.
204
212,213
Eddy current impedance plane
.
.. .. .. ..
213-217
'ledge and liftoff effects on . .. .
.
.
200,204
iddy current probes
.
!ddy currents
..
..
.
.
200-201
penetration depth .,.
.
.
202. 204~205. 224
"\~dy current testing
lapplications . . . . . . . . . . .
.....
200.202-203
J automotive industry
.
200, 232·238
bolt hole inspection
..........
228-231
! steel industry . . . . . . . . . . . . . .
.........
218-227
detector arrays . . .
...........,.,.
. . . . . . . . . . . " 201
,Himitations
. . . . . . . . .. 13, 202
multifrequency testing
. . . . . . . . . . . . . . .. 239-241
')optimal frequencies
........
. . . . . . . . . . .201-202
.!remote field
.
,,
206-211
.Jsignal analysis
.
,
. . . . . . . . . . . . . . .. .,. 201
Eddy current transducers
200,203-204
jhigh temperature application
' 224-225
llge effect
jeddy current testing . . . . . . . ..
213-217
immersion ultrasonic testing
,. .
,.........
412
I
Edge radioscopic image enhancement
,
185-187
Elastic behavior
477
Elastic waves
, , , . . . . . . . . .. 350
laser-generated
,................... ..,.. 370
Electrically induced magnetism
.
, 273·275
Electrical power supply hazards
45
Electric power transmission systems, thermography of
491
Electric resistance strain gages
507
Electromagnetic acoustic transducers (EMATs)
373-374
Electromagnetic demagnetization .. . . . ..
285
Electromagnetic-electronic methods
, .. , . . . . . . . . . .. 16
Electromagnetic induction testing . . . . . . . . . . . . . . . . . . . .
.. 200
geometric limitations ,.
13
special methods
.
,
503-505
units for
,...
. . . . . . . . . . .. .
, .. '. .. 21
See also Eddy current testing; Magnetic flux leakage testing
Electromagnetic radiation
. . . . . . . . .. 92-94, 480
absorption
........,..'
95-98. 144-146
scattering
,.
.
95. 96-91), 146-150
Electromagnetic radiation shielding
" 112. 123
Electromagnetic sorting techniques
........
. . . . . .. 212-217
Electromagnetic spectrum . . . . . . ..
92. 434, 480
Electron beam distribution, from X-ray tubes
' 102
Electron capture detector probe leak testing
.. , , . . . . . . . . .. 68
Electronic holography . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . 498
Electrostatic ultrasonic transducers
,.
. . . . . . . . . . .. 371
Emissivity
'
. . . . . . . .. .. 481~482. 483485
selected materials
.....
.
, . 48,5
Emulsifiers, in liquid penetrant testing
. . . . . . .. 82
Emulsions, radiographic films
" 157
EN 473
..........
.
80
Encircling eddy current transducers
. ............
204
high temperature application . . . . . . . . . . .
. . . . . . . .. 224
English units, conversions to SI units
,
19
Enlargement, radiographic images .. ,
134.1.38
Envelopes, for X.ray tubes
. . . . . . . . . . . . . . . ..
99
Environmental contamination, leak testing to prevent . . . . . . . .. 30
Environmental Protection Agency . . . . . . . . . . . . . . . . . . . . . . . . . .. 7
Etching cracks . . . . . . . . . . .
.
" . 264-265
Evacuated systems. See Vacuum systems
Explosion hazards .,.
............
. . . . . . . 46
Exposure, radiographic images
133-134. 137. 141-142. 1,59-161
Expulsion, in spot welding
.........
324. 327
Eye
'
428-430.432-434
light-dark effects
435
Eyeglasses
...................
430
Eye protection filters .
.
,
,
439
F
Fabrication discontinuities
,.
. . . . .. 2.59, 263-265
Failure
, ..
.
,
4
analysis by X-ray computed tomography. . . . . . . .
. " 195-196
rising costs of
,.
. . . . . . . . . . . . .. /
Farsightedness
............
. . . . . . .. 429
Far vision
,.....
429
Far vision examinations. . . . . . . .
.
430
Fastener holes, eddy current testing
228-231
Fatigue cracking
,... 266
ultrasonic testing
347
See also Crack detection
Fatigue strength. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .
266
INDEX I 511
Feature extraetfon ,
,,,
, ,. 468
Federal Aviation Administration
.
7
Federal Regulations Code: Titles 10 and 49 (radioisotope
handling)
", .. , . . . . . . . . . . . . .. .
,.,. 116
Feed-through coil eddy current transducers .. , .. ,
204
Felicity effect
,.. 304
in fiber-reinforced plastics
".. 316-317
Ferrite cores
eddy current testing . . . . . . .
. . . . . . . . . . . . . . . ... . .. 21,5. 216
for magnetic flux leakage testing coils
,........ 247
Ferromagnetic materials
, . ..
268
Barkhausen noise analysis .
505
discontinuities of .
..................
. . . . . . . 259-266
eddy current testing .... . . . . . .. . . . . . . . . . . . . .
213.215. 217
high temperatures
. . . . . . ..
223-224
production of
..........
. . . . . . . . . .. 2.59
properties . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . .. 278-280
See also Magnetic particle testing; Steel
Fiberglass laminates, thermography
.............. 489
Fiber image guides
.............
449-450
Fiber light guides
........ 4,s0
Fiber optics
borescopes
.
449-4,s0
radioscopy application .
182-183
Fiber reinforced composites. See Composites
Fiber reinforced plastic vessels, acoustic emission
testing
.
. . . . . . . 310-317
Field of view
.
....... .
. 428-429
borescopes
451,454
Fill factor, eddy current testing
204
Film badges
.
112, 127
Film contrast, in radiography
164-165
Film radiography. See Radiographic films: Radiography
Film speed
.
.
447
Film thickness
diesel engine piston eddv current testing ..
235
eddy current testing
.
232
Filters
eye protection
......... 439
optical
.
470
radiographic ..
148-150
Fissures, See Crack detection
Fixed grid testing .
497
Flakes..... .. .
.
262
Flammable liquids/vapors
44
Flash
.
262
Flash lighting
.. 469-470
Flash line tears
.
262,263
Flaws. See Discontinuities
Flexible membranes, for coupling in contact ultrasonic
testing. . . . . . . . . . . . . .
................
. 400-401
Flexible resin (composite discontinuity)
421, 422
Fluorescence . . . . . . . . . . . . . . . . . . . .
.........
435
Fluorescence detection
. . . .. 427
Fluorescent magnetic particles. . . . . . .
289.291
Fluorescent materials
,
" 435
Fluorescent penetrants
... " 76.81
Fluorescent SCreens. . . . . . . . . . . . . . . . . . .
1.54-156, 165, 166
radioscopic use
..........
174
Fluoroscopy
.
,
. . . . . . .. 174
limitations . . ..
13
See also Radioscopy
Flux leakage. See Magnetic Ilux leakage
Flyingrigs
,
" .. ,
,
,
Focused ultrasonic transducers .. ,
,............ .
Focusing, video borescopes
,
',
,....
Focusing cups, X-ray tubes
,
Foil resistance strain gages
, , . . . . . . . . . . . . . . . . . .. 507.
Forging blank testing
,
,
, , . . . . . . . . . . . . . . . ..
Forging bursts
,
'.,....... '..........
tu~bine rotor wheels
.
,
,....
Forging discontinuities .. ,
,
Forging laps
" .. ,.,
,............
Forked coil eddy current transducers
, .. ,
, . , . ..
Forster microprobes
,
,., .. ,
,.'.. '" 248.
;o;.Forwir~ obllque borescopes
.
,
Fracturepoint
. .. ,
,
Free convection
Free machihingsteel
,,.,
Front lighting
Full skip (V) test . . .. .
Full-wave direct current
Future usefulness, of test objects
,
,
.
,
390
46@
100,
508
5-6
262
416
262'
262
204
249
455
,
,
477
, . . . . . . . .. 478
, . . . . . . . . . . . . . .. 260
, . . . . . . .. '" 468-469
",....... 398, 405
"
.. , ,
466
281-283
, , . . . . . . . . .. 2.
G
Gage pressure .....
...........
. . . . . . . . . . . . . . . . .20
Galvanized steel, spot weld acoustic emission monitoring . . 328·329
Gamma radiography
. . . . . . . . . . . . . .. 132
See also Radiographic isotope sources, Radiography
e:-''P0sllre
exposure charts. . . . .
. .. , . . . . . . . . . . . .. 161
exposure factor . . . . .
. . . . . . . . . . . . . . .. 142
gam~11a ray equivalency
, , . . . . . . . .. 145-146
isotopes. . . . . . . . . . . . . . . . . .
.
" 114-119
source handling equipment. . . .
.
120·127
Gamma rays . . . . .
........
. . . . . . . . . . . . .. 92-93
. .. " 95-98,
absorption
.
scattering
~,
. .. .
.
.
146
sources. See Radiographic isotope sources
Gas cooled borescopes
.
.
.......... 452
..... " 318-321
Gas trailer tubing, acoustic emission testing
Gated system display, in ultrasonic testing
356.359
Gears
automotive pinion gear eddy current testing
............. 235-236
eddy current testing.
..,
.
232
.
.
................ 265
fatigue cracking . . .
Geiger.Muller meter
.
Gelatin ultrasonic testing couplants
.
.
General manager . . .
.
.
Geometrical optics
..
Geometric limitations, on methods
.
.
Geometric unsharpness, of radiographic images
134. 136-138
Geometry acquisition, by X-ray computed tomography
195
German DIN penetrameter
.
Glare.. . . . .. ..
.
.
" 516-564
Glossary of nondestructive testing terms . . .
Clycerine, as ultrasonic testing couplant
402
Graetz circuit, X.ray generators .
. . . . . . . .. '" 104. 105 ,I
Graininess, radiographic films . . . . . . . . .
.
166t,1
Grain size discontinuities
" 413-414'
Graphite-epoxy composites, thermography . . . . . . . . . . . . . . 488-489~
Grass
,............
392,.
Gray level
468,;
Grease, as ultrasonic testing couplant .
402
572 I INDEX
einacker circuit, X·ray generators
diaphragms
,
Grid spacing, in ultrasonic testing
ilt~~a~~<.>
. · ::.·.·. ·, , .·.
Culton whistle ,
~E~~~~(~~:::~~~Lt .' .'
".,. .
,' ,
, .. ,
, , , . .. 104, 105
" 150.151
, 404
~~:;
, .. ,.......
,
,. .
'
279
, 285
, 212
,
I
, . .. 61
', ,.. ~~~:-~i~
Halitation
,
,
"",
"" 463
effect devices
~ddy current testing .. ,
,,,
,,,
' 201
lnagnetic flux leakage testing . ' ,. ..",."
,... 248
Halogen diode detector probe leak testing,
,,,,
, .. 67-68
u:¥ogen diode leak testing
, , , .. ,
,
, .. '
, ,. 40
~ogen tracer gas techniques
,.', ,,,,,.,.,
, 34. 48
knd D curves, radlographicfllms ,.,., .. , .. ",.""" 161-163
Hand probes, for magnetic particle testing "., ..... "" .. ' 277
Y'~rdness testing "
",
,
,.,
,,,,,'
,. 2
bf automotive parts, by eddy current testing. ,
, 232,234. 236-237
lat affected zone cracks
, . " ' '",.',
,,'. 263
Heat transfer . . . . .
, .. , , , ,
, , , .. , . , . , . .. 478-482
:::::~racks .,
,'., .. ' " " ,
,
' .. " 264
H~
Ul::
Jamshaft inspection .. ,.".,'
,.,,.,
, .. , , .
237-238
eddy current monitoring
,,'.'
" . . . . . . . . .. 200, 202
errnanent magnet creation by "., ... ,' ..... , .. ,
"".,. 268
o rhine rotor wheels
"".....
, .. '
, , .. " 418
Lnd ultrasonic beam attenuation ... "' .. ",,..... ..,...... 392
Helium detector probe leak testing method
,
' 59
J;1'''pum mass spectrometer leak testing '.
34,37, ,59-60, 68
pr vacuum systems .. , . '. , ", .. , ..... ,
,
'
56
LlIium tracer probe leak testing method ,
,
, 59
Helmholtz resonator ' , . . .. ,.,., ... ,'
",'....
. . , ,. 61
P;~h frequency ultrasonic transducers ",
,
", 372,373
I 'o~ luminance visible light sources, hazards of " . """ 436-437
I"gh tension connections, X.ray generators,
, . , '. 105-106
High voltage electric transmission systems, thermography .... 491
P:$h voltage megavolt l"adiography ,'.' ..... ",' ... "., .. ' 151
I}togram equalization radioscopic image enhancement, , , , " 187
t,le penetrameters .. , , , , , , ' ... , , .. , .. , , , .. ' . , , , , , ,. 166, 169
Jiolography
,
, .. ,... .",.,.,,'
' 498-500
P'''Plomorphic filtering
,.'.,.
,.,,
, 187
lrd method, of helium leak testing
.. .. ~. 60
l'oDd, X-ray tubes ., .. ,
,
",
,'
1O~, 103
Horseshoe magnets ,., .. ,.,
,'...
270. 271
Ih~tears .. ,
,
,
"
,
,.
263
I i~-Nielson source
,.... .
,
"", 302
L.bs (automotive), eddy current testing
,,..
236-237
Huggenberger resistance strain gage ."
', .... ,...
506
p'"",maneye. See Eye
I firogen embrittlement
, ' .. , . ,
265
I lh-ophilic emulsifiers
,......
,.,'
, .. , . , . . .. 82
Hyperopia
,
, , ..
429
H',?erthennia ,
, . . . . . . . . . . . . . . . . .. . 437
1 ~eresis
;.agnetic
,
,,..
278-280
in strain gaging
,'
,...... 508
·
t
Hysteresis loops . ,
for demagnetization
for sorting .,
Illuminance,
" 21
Illuminated magnifiers . , . . . . .
. .. , . . . . . . . . . . . . . . .. 444-445
Illumination
,
,
,
440-441,442
Image converters
, . . . . ..
177
Image enhancement
in radioscopy
. . . . . . . .. 184-187
in visual testing . . . . . . . . . . . . .. ................,. 447-448, 468
Image formation
426
Image generation methods ,
,,
,..
. . . . . . .. 16
Image intensifiers
,
'
175·178
Image Isoeon tubes
,
180, 181
Image orthicon tubes
. .. ,
,,,
' 462
Image quality indicators
,,
,,
, 143, 166,169
Image segmentation
,
,.....
. ., 468
Image sensors
, .. "
,
,.,'... 47·471
Image tubes '"
".............. 180, 181, 182, 470-471
Immersion tanks
. ........ " " ........ , 408
Immersion ultrasonic testing ... , , . . . . . .. ."., 353,354,357,381
advantages , ' . , , . .
.
' .. ,
,'
, .. ", .. , 407
composites ,'
, .. ,...
"
"
",.. . 419·423
coupling ,'.
devices for
,
,'
,.....
407-410
,.,....... .,
,
".,.
408-410
"., .. ,.. ,., .. ,
410-414
discontinuitv location .. '
of rotor wh~els (aircraft)
"., ... '
,......
414-418
test parameters
' . . . . . . . .. .
:
,
410·411
Impact damage (composite discontinuity)
,
421, 422
Impedance method, eddy current testing
, .. , ,
, 203
Impedance plane analysis, eddy current testing. ,
212-217
Implosion hazards
46
Industrial gas trailer tubing, acoustic emission testing .,., 318·321
Infinite liftoff impedance
.. , , , , , . . . . . . . . . . .
, ... , 204
Infrared method~
,..
.
,,
, , . , . .. .. 16
Infrared radiation
,,
',,
,....
. ., 92,480-481
hazards. ,
' .,. ,,...... .
,,
437.438
Infrared thermography
,
,
'
16.474,478-482
applications .... , . , . . . .
. , , , , .. '
,.,...
486-496
instrumentation/techniques . , .. , , . . . . . . .. ,.,
,... 482-485
Ingot cracks ,'... .
, .... ,.".........
. .. ,
, 260
Ingots
"..
..
"
, 259
Inherent detector leak testing
,. ' . . . . . . . .. .,.......... 35
Inherent discontinuities .. .
, . . . . . . . . 259-260
Inhomogeneous materials, ultrasonic wave propagation in .... 350
Initial pulse, thickness gages
.
'....... 368
Inspection . .
,
,
,
,
9
departments and . , . '
,
, .. , . . . . . . . . .. 11
management '..... .
"................ ",.,.,. .." 12
receiving
'.,
'
,
,
, . . . . . .. 11
responsibilities in .. ' .. , ,
,
, . . .. 7-8
Inspectors
responsibilities
,
'
,'
,'
,. 7·8, 12
skillsand judgment of
'
,
, 14
Intensified silicon intensifier target (SIT) tube
,........ 180
Interface triggering
, 367
Interferometry
holographic
moire
' . . . . . . . . . . .. .
,
, .. "
,
, .. ,.. 498·500
,
498
INDEX I 573
shearography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 500
speckle
498
Interlacing. . . . . . . . . . . . . . . . . . . . . ..
183.462
Internal conductor magnetization .. . . . . . . . . . . . . . . . . . . . . . .. 273
Internal evaluation of parts, by X-ray computed
tomography
188,190·192
International Institute of Welding reference block . . . . . . . . .
397
International Organization for Standardization (ISO)
film speeds
447
178
ISO 1000 . . . . . . . . . . ..
ISO 9712. ..... . .... ..
. . ..
. . .. .
..
80
International Radiation Protection Association . . . . . . . . . . . . .. 437
Interpretation of results, limitations on
13
IntrlI1sic moire method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 497
Inverse square law, and radiography
139
Ionization chamber meter
.. 113
lridjum-192
115, 116-118, 145
Iris....................
..
429
ISO. See International Organization for Standardization (ISO)
Isocon tubes .
.
, 180, 181
Isotopes. See Radiographic isotope sources
J
Jaeger eye chart
. 430,431
Jet engine burner, video boresoope inspection
460
J fasteners, X-ray computed tomographic evaluation ......... 191
Joints
leak testing
28-29, 50, 54-.55
See also Welded joints
Journals, fatigue cracking
.
... 266
K
K absorption edge
. . . . . . . . . . . . . .. 96
Kaiser ~ffect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 302-303. 304
Klien-Nishlna formula . . . .
. . . . . . . . . . . . . . . . . . . . . .. 96
Knot (composite discontinuity) . . . . . . . . . . . . . . ..
..
421
L
Labor.................
.
7
Lack of fusion/penetration weld discontinuities . . . . . . . . . . . . .. 263
Lack of rovings (composite discontinuity) . . . . . . . .. ..... 421. 422
Lamb waves
..
. . . . . . . . . . .. 396
Laminate composites
,
,
419,423
See also Composites
Laminations
261
Lampblack .
.
,
, . . 482, 484
Laps. . . . . . . . . . . . . . . . . . . . . . . .
.
261, 262
Laser applications
holography
.,
498-500
leak testing . . . . . . . . . . . . . . . . . . .
. . . . . . .. .. 3940
point triangulation profilornetry
500-502
shearography
. . . . . . ..
500
ultrasonic testing
' 370·371
Laser eye protection
439
Laser hazards
, ..
436
Lead foil screens. . . . . . . . . . . . . . . . . . . . . . . .. 147-148, 151, 152·154
and graininess ..
166
Lead zireonate titanate transducers . . . . . . . . . . . . . . . . . . .. 352·353
Leakage rate
26-28
acoustic signal dependence on
63-64
bubble equivalents
41
conversion factors for
27
gas tracer measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 36
minimum detectable
, . . . . . . . . . . . . . . . . . . . . .. 26
.50-53
pressure change tests for
. . . . ..
and pressure differential
, , .. "... 27
quantitative description
, .. ,.......................... 27-28
.and serviceability , . , ... , , , ' . . . . .. . ... ,.. . .. ,........... 26
.;:~~u~;,;~~~· :::::::::.. :::::::::::::::::::::: :::::.20'.' ~
Leak conductance ...... ., ... ., ..... ., ... ., . .,.,...... .. 27
Leak locati~;; . '. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 32, 34-35
. . . . . . . . . . 38·39
coordinating v.1th leakage rate measurement
electronic detectors for
, 38
individual leaks
,
"..................... 38
method sensitivities compared
'.
39
Leaks .. ,
,
26
.. ,
, ., 61. 63
acoustic characteristics
flow modes through
,
, . , , , , , ,. 49
reference leaks
,...................... 49
Leak testing, .. ,
,,
25·74
applications .... , . . . . . . . . . . . . . . . . . . . . . . . . . . .. 26, 28-29, 32, 33
categories of
. , . .. .,.".,.............. 32-34
leak detectors
,
"".,... 31
fluid media used for
,.....
. . . . . . . .. 32, 34
impractical specifications ,.
.
,.
29
individual leaks . . . . . . . . . . . . . . . . . . . . . . . .
.
26-27. 38
laser application ..
. . , .. , . . . .. 39-40
leak detectors
,.,
, 31
locating all leaks
'
, . . . . . . . . . . . . . . . . . . . .. 29-30
32, 33. 35·36
method selection decision tree ".,....
open test objects. accessible on both sides
36-37
personnel training,
,.......
.
40-41,43
safety aspects
,.,.". 4247
sensitivity-cost relationship
. . . . . . . . . . . .. 32
30·32
sensitivity for practical applications
,...
SNT-TC-1A and
40-41
standard conditions for
, . ,. 31
storage tanks . . . . . . . . . . . .. .
:................. 65·69
systems leaking to atmosphere
,
37-38
units for
, .. , ' . ,
,
",
20-21
vacuum systems. See Vacuum systems, leakage rate/testing
See also Acoustic leak testing; Bubble leak testing: Helium mass
spectrometer leak testing; Mass spectrometer leak testing
Leak tightness
..... , . . . . . . . . . .. 29-30
Lenses
for optical coupling in radioscopy
".................... 182
ultrasonic
,.................. 390-392
with ultrasonic transducers
,....
.
, . .. 354
Liftoffcurves
,............. ,
, .. ,. 204
Liftoff effect
,. .
,...
202
"
,.,
,
213·217
and impedance plane
Light amplifiers
.
".,
,.... .,..... 177
Light guides
.,
.. .. .. .. .. .. . .. .. .. .. ... 450
Lighting
, . . . . . . . . . . . . . . . . . . . . 440
machine vision systems
, .. ,
, .. ,... .. 468470
photography .. ,.,
,... 446
Light intensity
,
,
440441
Light sources
,.,
,
,
,.... 426
hazards
, .. "
,.,
,
436-438
574 / INDEX
Limited angle computed tomography,
, , . .. .
190
Linear accelerators
107, 108
Linear elastic waves
' . . . . . . . . . . . . . . . . . . . . . . .. 350
Line focusing
100
Lines of forces, magnetic fields
. . . . . . . . . . . . . . . . . . .. 267
Lipophilic emulsifiers
82
Liquid film bubble leak testing
57-58
Liquid penetrant developers.
77, 82-83
Liquid penetrants
76.81·82.83
Liquid penetrant testing
. . . . . . . . . . . . . . . . .. 76-88
advantages/disadvantages of . . . . . . . . . . . . . . . . . . . .. 13, 78-79. 85-86
applications
.
, 77-78
automated inspection systems
. . . . . . . . . . . . . . . . . . . . . . . . . .. 80
equipment for
79·80
history of . . . . . . . . . . . . . . . . . .
..
76
part protection after testing ..
87-88
personnel.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. .. 80
process description
. . . . . . . . . . . . . .. 76-77, 86-88
process selection
. . . . . . . .. 84·85
sensitivity. . . . . . . . . . . . . . . . . . . . . .
. . .. 83
Lithium niobate crystals
........... ....
. . . . . . .. 354
Lithium sulfate monohydrate crystals ..... . . . . . . .
352. 354
Load transducers . . . . . . . . . . . .
. . . . . . . . . . . . . . .. 508
Logarithmic processing radioscopic image enhancement ..... 187
Longitudinal magnetization. . . . . . . . . . . . . . . .
270~271. 274
Long pass optical filters
.
470
Lorentz forces
. 373
Low frequency ultrasonic transducers .
. .. " 371-372
Low modulus fibers (composite discontinuity)
421, 422
Low power microscopes . . . . . . . . . . . .
44.5-446
Luminance ....
. . . . . . . . . . . . . . . . . . . . . . . . . .. 21
Luminous energy tests
426
M
Machinery, increased demands on . . . . .
. . . . . . . . .. 6-7
Machine shops, borescope application . .
452-453
Machine vision technology
468-471
Machining tears .. . . . . . .
..........
263
Macroseopes, wide field
. . . . ..
446
Magnetic Barkhausen effect method . . . . . . . . . . . . . . . . . . . . .. 505
Magnetic domains
'. 267, 268
Magnetic fields
....... ..........
267-269
circular
270
right hand rule for . . . . . . . . . . .
.
274
Magnetic field strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271
Magnetic flux
267. 278
Magnetic flux density . . . . . .
..... ...
270. 278
Magnetic flux leakage
.
" 242. 258
Magnetic flux leakage fields . . . .
270
Magnetic flux leakage testing
242
applications
,......
250_253
pipeline
........
. . . . . . . . . .. 252-253
steel industry
. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 218
tubing
250~251
wire ropes
.
251-252
part types mspectable
142-246
sensors for
246·250
Magnetic hysteresis. See Hysteresis
Magnetic materials
268
Magnetic particles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249-250, 258
dry powder
289, 290-291
Iluorescent
289. 291
mobility
290-291
particle shape effects
289·290
particle size effects
289
properties . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 288-289
visibility/contrast
290
wet method
289,290,291
Magnetic particle testing
76. 257-295
capabilities/limitations .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 258
demagnetization. . . . . . . . . . . . . . . . . . . . . . . .. 258, 269, 282, 284-287
discontinuity t:'pes and
. . . . . . . . . . . . . . . . . . . . . . . . . . .. 259-266
orientation effect
272
subsurface ..
271
equipment for..
276-277
limitations .. . . .
. . . . . . . . . . . . . . . . . . . . . . .. 13
magnetizing current
281-283
media selection
. . . . . . . . .. ..,..... 291
mobile/portability test systems '"
. . . . . . . . . . . . . . . . .. 276-277
processes
. . . . . . . . . . . . .. 291·292sensitivitv . . . . . . . . . . . . . . .
. . . . . . . . . . ..
10
units for . . .
. . . . . . . . . . . . . . .. 21. 278
Magnetic permeability. . . . . . . . . . . . .
. . . . . .. .. 280, 288
Magnetic poles. . . . . . . .
.
267-268.270
Magnetic recording tape . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 248
Magnetic resonance imaging (MRI)
. . . . . . . . . . . . . . . . . . . 504
Magnetic saturation.
. . . . . . . . . . . . . . . .. 278
Magnetism
. . . . . . .. 268-269. 270
electrically-induced. . .
. . . . . . . . . . . . . . . .. 273-275
mechanically-induced
. . . ..
269
residual
. . . . . . . . . . . . . . . .. 278. 280
units for .
. . . . . . . . .. 21. 178
Magnetization . . . . . . . . . . .
. . . . . . . .. 269
circumferential ...
. . . . . . . . . . . . . .. 273-274
internal conductor
, .... " 273
longitudinal. . . . .
. ... 270-271,274
multidirectional .
............
. . . . . . . . . .. 275
Mag-nctizing current. . . . . .
. ... 281-283
Magnetocuodes
248.249
Magnification
.. ..... 454
borescopes
.
464
'videocameras
.
.
Magnifiers
.
.......... 443-445
Manufacturing
cost reduction with nondestructive testing ..
. . . . . . . .. 5-6
discontinuities of . . . . . . .
. . . . . . . . .. 259. 263-265
Masks, radlographic . . .
...................
148
Mass flow rate (in leak testing). See Leakage rate
Mass spectrometer leak testing
. . . . . . . . . . . . . . . . . .. 40
for vacuum systems
55-56
See also Helium mass spectrometer leak testing
Match band effect
. .. ....
. . . . . . . . . . . . . . . . 447
Material composition. . . . . .. . . . . . . . . . .
.. 16. 17
of automotive parts. eddy current testing. .
.
Material flaws
internal evaluation by X-ray computed tomography
188. 190·192
leak testing evaluation
. . . . . . . . . . . . . . . . . . .. 28-29
radioscopic detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 186
See also Crack detection; Discontinuity detection; Leaks
Material properties
eddy current testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 200, 202
and material behavior
. . . . . . . . . . . . .. 475, 477
INDEX I 575
testing methods
.
13. 16, 17
Materials
anisotropy
. . . . . . . . . . . . ..
349. 350
demand for sounder materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7
inserviee inspection
, ..
. . . . . . .. 15
limitations on methods
13
See also Composites; Ferromagnetic materials
Materials engineer . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12
Matrix structure determination
.
16. 17
McClurg formula
, . . ..
. . .. 250
Measure, units of. See 81 units
Measuring magnifiers
444. 445
Mechanical joints. See Joints
Mechanically induced magnetism .. . . . . . . . . . . . . . . . . . . . .. 269
Mechanical-optical methods . . . . . . . . . . . . . . .
. . . . . . . . . .. 16
Mechanical properties. . . . . . .
.............
16. 17
Medical nondestructive testing .....
. . . . . . . . . . . . . . . . .. 2
Medical tomography
..................
. ... 188
Membranes, for coupling in contact ultrasonic testing.
400~401
Metals
allovidentlftcation . . . . . . .. .
474.475.503.504
eddv current testine;. See Eddv current testing
Kai~er effect
~. .
:
~ .
302-303, 304
radiation absorption . . . .
.
.
. .. 94
radiographic equivalence factors
lAS
as radiographic filters .. . ..
149
ultrasonic beam attenuation by
392
See also Aluminum; Steel
Metric system. See 81 units
Metrology ...
.... 16.17
Microchannel arrays .,.
177
Microfocus X-ray sources
l7.'5
Microscopes ...
443. 445-446
television application
.
459
Microseismie activity. See Acoustic emission
Microstructure determination
........
16. 17
Microwave testing
..........
.
476.505
MIL·I·25135 . . . .
. . . . . .. 83
Miniboreseopes . . . . . . . . . . .
...........
451~452
Minimum detectable leakage
. . . . . . . . 26
Mirrors, for optical coupling in radioscopy ....
182
Modulation transfer functions
186
Moire. .. . . . ..... ..
497
Moire interferometry
........
498
Moire testing . . . .. .
497 ~498
Moisture detection (buildings)
............
. .. 490
Monochromatic X-radiation . . .
..............
93~94
Monochromators
.
"
426
Multidirectional magnetization
.... ..........
.
275
Multifrequency eddy current testing
239·241
Multiple acoustic emission sensors . . . . . . . . . . . . . .
. .. 62-64
Multiplier phototubes
. . . . . . . . . . . . . . . . . . . . . . . .. 458
Mushroom eddy current probes
. . . . . . .. 204
Myopia.................. .
.
429
N
National Materials Advisory Board Ad Hoc Committee on
Nondestructive Evaluation, methods classification
scheme ,.......................................... 15-16
National Safety Council
7
Naval Submarine Medical Research Laboratory, color vision
classification scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 433-434
NDT. See Nondestructive testing
Nearsightedness
, . . .. . . . . . . . . . . . . . . . . .. 429
Near vision
429
Near vision examinations
430
Neighborhood processing radioscopic image enhancement. . .. 184
Neutral density optical filters
, 470
Neutron absorption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 98
Neutron generators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 133
.' Neutron irradiation
,
,. 98
Newvieon Cameras
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 180
'. ~oriaqu~ous_ penetrant developers
83
Noncontaet-ultrasorne testing . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3iO
Nondestructive characterization
.
474
Nondestructive evaluation. See Nondestructive testing
Nondestructive examination. See Nondestructive testing
Nondestructive inspection. See Nondestructive testing
Nondestructive characterization. . . . . . . . . . . . . . .
2.474.476
Nondestructive testing
applications
. . . . . . . . . . . . . . .. . . . ..
2-6. 15
defined
"
"
2
developments leading to rapid growth and acceptance of . . . . . . . .. 6-8
engineer
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 12
future usefulness of parts and
. . . . . . . . . . . . . . .. 2
glossary of terms
.................
. .... 515-564
information sources
........
........
. . . . . . . .. 12
limitations on ...
.........
. ..... '. .. 13-14
method classific,ltion
..........
. . . . . . .. 1.'5-16. 476
objectives
11
i;S. attributes measured. . . . . . . . . . . . . . . . . .
. . . .. 17
as panacea
.
...... 8
policies for
.
......... 11-12
properties measured: limitations on number
......... 13
reliability
.
. ... 14
scheduling
.
. . . . . . . . . .. 14-15
............ 12-14
sensitivity/accuracy specification
.
sensitivity range . . .. .
.
....... ,
10
81 units for
.
.
, .. 18-22
special methods
,
.
.
474-477
specification of tests
.
..... 11-li
visual aspects of methods
.
..
426
See also Inspection
Nonfluorescent colored penetrants . . . . . . . . . . . . . . . . . . . . . . . . . 76
Noninvasive medical diagnostics
, . . . . . . . . . . . . .. 2
Nonlinear elastic waves
, . . . . . .. 350
Nonmetallic inclusions
,........
260
North poles
, . . . . . . . . .. 267
Nuclear magnetic resonance imaging (NMRI)
, . . . . . 504
Nuclear power plants, borescope application
453. 461
Nugget formation, in spot welding
324, 327. 329-330
o
Occupational Research Center, vision acuity examination slides 431
Oil-and-whiting penetrant method
is
Oils, as ultrasonic testing eouplant
402
Oil well casings. See Well casings
Optical coupling
182-183
Optical fdtering
470
576 I INDEX
Optical testing
. . . . . . . .. . . . .. . . . . . . . .. . . . . . .. 426, 497·502
safety aspects
435-439
51 units
21
See also Visual testing
Optical units
21
Optics
. 426427
Overstress cracking . . .. . .. . .. . . .. .. . . .. . . .. .. .. .. .. .. ... 266
Oxtails
~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 103
p
Pair production, high energy photons
97
Panoramic boreseopes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 452
.~~ Paramagnetic materials
, . . . . . ..
268
1Partial volume effects
195
. Particle accelerators
. . . ..
98
Passive infrared thermography. . . . . . . . . . . . . . . . . . . . . . . . 482, 484
'~'lPavement, thermography. . . . . . . . . . . . . . . . ..
491-492
i Pencil eddy current probes .. '...
204
'Penetrameters
, .. 14.3.166-169
Penetrants. See Liquid penetrant testing
Penetrating radiation methods. See Radiography
'1
:::::::t:::~;e~~ ::::::::::.::::::::::::::::::::...... ~~~
I
Permeability (magnetic)
280, 288
] Personnel monitortng, in radiography ..
. . . . . .. 112
I Personnel training. See Training
J Petroleum industry
borescope application
453
See also Pigs; Pipelines; Well casings
Phase vectors . ..
. . . . . . . . . . . . . . . .. 212-213
Phasor diagrams
,
. 212-213
462
Photoconduction
)Photoconductivecells
. 457
458
\Photoconducti~elag
.
Photocurrent SIgnal
. 178
Photodiodes
.
arrays
178-179
visual testing application
457
Photodisintegration .
95, 97
Photoelastic coatings. . . . . . . . . . . .. .
475
I Photoelastie stress analysis ..
507
. Photoelectrl.c devices
,
457,458-459
, Photoelectric effect
9.5-96
Photoemission
. . . . . . . . . . . . . . .. 462
1Photoemissive devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 457
Photograp~c density, radiographic IIlmS .... . . . . . . .. 158., 15:
. Photographic films . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 44 i
Photography
446447
with bores copes
........
. . . . .. 455-456
Photons
92, 435
absorption
. 95-96
scattering
95, 96-98
f Photosensitizers .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 438
i Phototubes .....
. .. 458
J Photovoltaie cells
,
, . 457458
Physical properties
16, 17
1Piclding cracks . . . . . . . . . . . . . ..
264-265
i Pickup coils
,
,.,.......... 246-247
I Piezoelectric transducers
. . . . . ..
352, 365
Pigs
252
I
J
i
Pinehwelds, on undersea repeaters, acoustic emission
testing. . . . . . . . . . . . . . . . . . . . .. .
334-336
Pinion gears (automotive), eddy current testing . . . . . . . . .. 235-236
Pipe (discontinuity type) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 259-260
Pipelines
acoustic leak testing
., . . . . . . . . . . . . . . . .. 62
magnetic flux leakage testing
243-244,252-253
Pipes
fiber-reinforced plastic, acoustic emission testing
312-314
remote field eddy current testing of walls
206, 207-211
rotating pipe eddy currenttesting system
220-222
threads, magnetic flux leakage testing
245, 246
visual testing
465. 466
See also Tubes
Piston rods, forging laps ..
263
Pitch and catch ultrasonic transducer
configuration
. . . . . . ..
354, 356, 380, 396
Pitting
266
Planck's Distribution Law. . . . . . . . . . . .
.
481
Plastic deformation
477
acoustic emission and
298
Plating cracks .....
. . . . . . . . . . . . . . . . . . . .. 264-265
Plumbicon cameras
180
Ply gap (composite discontinuity)
. . . . . . . . . . . . . 421
Point processing radioscopic image enhancement
184
Point triangulation profilometry . . . . . . . . . . . . . . .
500-502
Polycrystalline ceramics
. . . . . . . . . . . . . . . . . .. 352, 354
Portable testing apparatus
13
Positioning and transport systems
. . . . . . . . . . . . . . . . . 465
Postemulsifiable penetrants
81-82,84,85
Pot core eddy current probes
.. .. .. .. .. 204
Potential drop testing, See Resistivity testing
Potter-Bucky diaphragm
.. 150, 151
Potting compound.
. . .. .
105-106
Power packs, for magnetic particle testing . . . . . .. . . . . . . . . . . .. 276
Power plants, boreseope application .. .
. . . . . . . . . . 453, 461
Preamplifiers, for acoustic emission testing
301-302
Preattentive processing . . . . . . . . . . . . . . . . . .
. .. ... 428
Pressure change leak testing ..
40, 50-53
Pressureeoupling ... ,.................................. 402
Pressure units . . . . .
. . . . . . . . ..
20, 51
Pressure vessels
acoustic emission testing
299, 300, 310-317
leak testing. .. . . . . . .
. . . . . . . . . . . . . . . . . . . . .. .. 46, 52
visual testing
453
Primary processing discontinuities
. ..
.259,260-262
Principal plane of focus
446
Probes
for eddy current testing ..
200, 204
for magnetic particle testing
277
Probe transducers
. . . . . . . . ..
224
Process engineer
. . . . . . . . . . . . . . . . . . . . . ..
12
Prods
277
Product design, role of nondestructive testing in
. . .. 5
Product failure analysis, by X-ray computed tomography .. 195-196
Product reliability. See Reliability (product)
Projected moire method . . ..
497
Proof' testing
.. .
2,51-52
Proportional elastic behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 477
Prototype evaluation, by X-ray computed tomography
195-196
Pseudoeolor
187
Pseudo sources, of acoustic emission
298
Pulse echo ultrasonic testing. See Ultrasonic pulse echo testing
INDEX I 577
Pumping speed, vacuum systems """,................... 55
P-yrometry
,
, , .. , .. ..
482
a
QPL·25135
,.,.""",
" .. , .. ",
,,' .. , 83
Quality assurance . ."
""""
,.",
9-10
role of nondestructive testing in .. , .. ,.,
".. " . " " " " . 6
Quality control
,.,., .. ,.",
9, 10
Quality levels .,.,
"..
. . . . . . . ..
6, 10
Quality specifications
,.,,
, . , ' , , . , .. , . , , . , .. 10, 11
Quartz crystal transducers
352
Quasilongitudinal elastic waves ,...
. . . . . . . .. 350
Quasishear elastic waves
" 350
Quench cracking .... , . .
.. .. .. .. .. . .. .. .. .. .. ..
264
R
R-12
48
R·22 . . .
.
48
R-134a . . . .
. . . . . .. . . . .. . .. .. .
.
48
Radar...............................
.
505
See also Microwave testing
Radiation. See also Electromagnetic radiation
heat transfer
. . . . . . . . . . .. 478. 480-482
methods of nondestructive testing . . . . . . . . . . . . . ..
.. 16
shielding. .
.
: . . . . . . . . . . . . . . . . . .. 112, 122. 123
Radioactive Materials, Regulations for Safe Transport of . . . .
116
Radioactivity
114
Radiographic exposure devices
classification
......
.
.
120-122
.... 120
manual source manipulation
.
120-127
remote handling eqUipment ..
See also X-raye;,:posure
Radiographic contrast
142, 164-165
Radiographic diaphragms/masks
........
.
148. 1.50
Radiographic equivalence factors
144, 14.5
Radiographic e":posure factors
133-134, 137, 141-142, 159-160
Radiographic films
132. 157-163
characteristic curves '"
161-163
grammess
. . . . . . . . . . . ..
166
handling
. . .. ,..................................... 170
photographic density
.. 158, 1.59
selection
142-143, 158
storage
"........................... 170-171
Radiographic filters
. . , , , " 148-150
Radiographic isotope sources
114-119, 133-134
characteristics of widely used , . .
...............
. . . .. 115
handling equipment
120-127
handling regulations/requirements . . . . . . . . . . . . . . . . . . . . . . . . .. 116
Radiographic screens
..,
147-148, 151, 152-156
and contrast
,
, . . . . . . . . . . . . . . . . . . . . .. 165
functions of
,
,,.,
,.,
, . , . . .. 152
and graininess
' , . , .' "
,."." .. "...... 166
screen mottle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 155, 166
Radiographic sensitivity
,
,
' . 10, 143, 164
factors controlling
,
, , , , , " 165
Radiographic shadows
134-139
Radiographic testing. See Radiography
Radiographs. , .. , . ,
,
132,170-171
Radiography
"
132-133
applications
, , , .. , .. , . ,
,
, .. " 132-133
computed tomography
188-196
us, HIm radiography
, , . , . , , .. , ,
, . . . . .. 188-189
diffraction mottling "
, , , , , . . . . . . . .. 151
e};posure chart
159-160
image interpretation
"
,
,
,. 169
image quality
164-169
limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 13
. :. milliapiperage-distance relationship .,." .. ,.", .. , .. 139-140, 141
• ;t;..millihrnp¢rag,e-time relationship . . . . . . . . . . . . . . . . . .. . . . . .. 140, 141
penetrating-radiation methods
, , ". 16
radiation' iibS9rption
,."
,................. 144-146
radiation scattering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 146-150
real time. See Radioscopy
,
174
reciprocity law
140-141
safety
,,,
112
serup diagram
132
shadow formation: geometric principles of . . . . . . . . .. .
134-139
distortion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 135-136
enlargement
134, 138
geometric unsharpness
, . . . . . . . . . . . . . . . . . . . . . . .. 136-138
inverse square law
.
,. 139
rules for successful
135, 136
. . . . . . . . . . . . . . . . . . .. .., 18-20
51 units for . . . . . . . . . . . . .
time-distance relationship
140
X-raycomputed tomography
, . .. 188-196
us, film radiography
188-189
See also Radioscopy;X-ray computed tomography;X-ray Generators
Radiometry
482-485
Radioscopy
174-187
image enhancement techniques .,.....
. , . . ..
184-187
image intensifiers for
175-178
optical coupling . .
,
"
",..
182-183
remote viewing system
176. 183
spectral matching of phosphors and photocathodes
177-178
system setup
,.... .
. . . . . . . . . . . . . . . . . . . . . .. 175
television c~mcras for . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 178-182
viewing/recording systems
,.......
.
" 176. 183
Radio waves
,............ 92
Radium-226
. .. , , , , . . . .. 114
Rare earth phosphors
. . . . . . . . . . . . . . . . . . . . . . . .. 177
Raster. . . . . . . . . . . . . . . . . . . .. .
461·462
Raw material inspection
15
Rayleigh waves
349-350
Reade~s
,... 443-444
Real time radiography. See Radioscopy
Real time radiometry
483
Receiving inspections
,. .".,
, .. ,
,... 11
Reciprocity law, radiography
140-141
Reference leaks .. ,
,
,.,............... 49
Reflected moire method, ,
,.',."
,.. 497
Reflection ultrasonic testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 351
Reflector plates, use in immersion ultrasonic testing
420
Refrigeration equipment, leak testing "."
",....... 3.5
Regulations for Safe Transport of Radioactive Materla18 ..... " 116
Reliability, of nondestructive testing methods . . . . . . . . . . . . . . .. 14
Reliability (product) " . , . ,
, . . . . . . . . . . . . . . . . . . . . .. 3-5, 9
assurance through nondestructive testing . ,
, , . . . .. ,. 3-5
Seealso Quality assurance
Reliability (system), leakage testing
26,28
578 I INDEX
, ' . . .. 278
Remote field eddy current testing ... , ... , , .. ,
,... 206-211
Remote positioning and transport systems "".,
465-467
Repeaters, undersea, acoustic emission testing
,
331-336
Residual gas analyzers
,
',
,., .. ' 55-56
Residual magnetism
, .. ' . ' . ,
. , , .. , . . . .. 278. 280
Residual stress cracking
.,.,.,
,",.'.. 264
Residual test method, of magnetic particle testing,
291-292
' 402
Resins, as ultrasonic testing couplant '.", .. ,
Resin starved layer (composite discontinuity) . ' . . . .. .. . 421. 422
Resistance spot welding, acoustic emission monitoring , . .. 323-330
Resistance strain gaging , , .. ' ,
,.,
' . " , .. 506~508
RE~sis:tivity (potential drop) testing
,..
212.476.503-504
" .. ,
,'
, .. ,
' 21
measurement units
Resonance transformers, for X.ray generators .".
106
Responsibility" in inspection ... " " " , ""
, , . , ' .... , .. 7-8
Retentivity ... , , ' , . ' , , , , . .. . " . " " " " " ' "
268, 278
Retina .
.
".
429, 432
damage to
,
' .. , , . . .. 436. 438
Retrospective boreseopes
'
, , , .. , , .. ".,.,.,.,
455
Return trace " .. ,.,.,
' .. ' , ,
' , , . , . " 461, 462
Reverse engineering, by X-ray computed tomography .. , ' , . " 19.'5
Right angle boreseopes ,' .. ,
,
,
455
Right hand rule, for magnetism, . .
. . , , . , , .. 274
Rigid borescopes
'
,
,,...
' ,. 450~452
Ringing technique, for contact ultrasonic testing " " " . . 402-403
Robotic camera transport systems
, , , , .... , , . , ..... ,. 465, 466
~l Rocket motors, internal evaluation by X-ray computed
j tomography
195
.. Rock noise, See Acoustic emission
Rod anode, X·ray tubes , , ..... ' , , ' , .. , .
103
Hemananee . " " " " " " " " " " " " ' "
l:::~;e~a~~ ~~~~d' bill~t~~ ~dd; ~~~~~t' ~~sti~g .
.1
:;~
Rotating pipe inspection system " " " " " " " "
220-222
Rotational soldering, of undersea repeaters. . .
331, 332
Rotor wheels (aircraft), immersion ultrasonic testing of
414-418
Round bar inspection system "
,
,. ..
220
Rounding off " " " " " ' . . . .,......'., , , ' .. , " ... , , ., 21
s
1
ISafety
.
\
leak testing . , . ,
' , , . , .. , .
42-47
optical/visual testing .,..
' ,.,.,.,,.,.
435-439
' . , .. " ,
public demands for'increased
.. , .. ,
,..
122·127
radiographic source equipment, '
X-ray generators '. ' . , , , ' . . . . . .
.
,,,,'
112-113
Sampling , ,
,
,,,,.,,,'
, , .. , , ,
,. ,
, 2
Saturation point
' .... , ... , . . . . . .
. .. , " . 278
Scabs .......... ,...........
. .. .. .. .. .. .. .. .. .. ... 263
Scanning, in television systems
,,
461·462
Scanning limitations, on methods ..
,
, ,. 13
Scanning radiometry ,. . . .
' , .. , . , . , 483
Scattering, of radiation ,'
,
,
, .. 95.96-98. 146·150
Scheduling tests .,
,
"
"" .. ,,"',. 14-15
Screen effect, X-ray tubes "' .. , . , . " " " " . , . " " " , , 100-101
Screen mottle ., .. ,
"""
".,., .. , .. ',.", 155. 166
Seams ,
"".,
""".'"
" " , " " " ' , . 260-261
Secondary processing discontinuities " " ' . " ,
259, 263·265
Secondary sources, of acoustic emission
' , , ' , . , . , , " 298
Second generation image converters .. ,...... " ..... , ... 177
Sensitivity specification ,.,.... .
" " , .. ,............ 12-14
Separations
,,,,.,.,
,
'
,,........
16, 17
See also Discontinuities
Serviceability, leakage rate and . , , . , , ,
' , . , . ,.
26
Service damage, limitations on testing for
, , , , , ' , . , . . . . . .. 14
Service discontinuities , .. ' . , . . .
,,,,.,
, . . . . . . .. 259. 266
Shades (eye protection) , , ' , , , , . , .. , ..... , , . ' .. , , ... , . " 439
Shadow formation, in radiography, . .
' , " " ' " , . " . 134-139
Shadow moire method .
.. " , .... " .. .. . .. .. .... 497
Shafts, automotive axle shaft eddy current testing
232-234
Shake and bake
'
,. . . , , . , . . . . . . . . . . . . . 505-506
Shape limitations, onrnethods , ,
,.,
, , .. , "
, 13
Sharpness, of radiographic images .,...
, , . , ' , , ,. 134, 136-138
Shearography
,,,,,,.
.,,,,,'
' . , , . . .. 500
Shear wave angle
.. ' , , , , ,
, , ' ,. 397
Shielding (radiation)
',."
. , . , . , , , , , . , , .. 112. 123
Shrinkage cracks '
' ,,. ,
' .. , , . ,
,. 263
Sig.ht .. , , ' , , , , , . , , . , . , , ..... ' , . ' , ,
., 428-429. 432-434
Signal image analysis methods
' , , . , . , .. 16
Signal value
' , .. ,. 317
Signature analysis "." ... '",,'.
16. 17
Silicon diode tubes. , , .
' , , , ' , , , .... ,
180
'.,
' , . , , , , , . . .. 180
Silicon intensifier target tube
Single-phase full-wave direct current "'" , , . , .. ' ..... ' " , 282
Sistering
, .... , . , , ,
467
' , ... , , . .. 18-22
SI units ' , , . , , , , , , , ... ,
, , , , , , , . , , . , ... ' , ,
19
conversions for obtaining
' , , , . . .. 18
derived " " " " " , ,. , . .
for nondestructive testing methods
, , , , . , .. , 21
electrical and magneti; testing
leak testing
,
20-21. 26-28
21
optical
, , , , , . , , .. , .. ,. 18-20
radiograph}
us. decibel
21-22
22
prefixes for
' , , . , , , ....
table of ., ... , , ... ' , , ,
.... ' . , , ... 18
.. . ..... 13
Size limitations, on methods , , , , .
, , . , .. , , , , . . . .. 205. 208
Skin depth , , , , .. , , , ... ,
Skin effect
' ,,,.,.,,.,. ,
204-205.281
,."'.,,,
2.'59
Slabs '"
,,.,.',,,.,,.
SNT-TC-IA, ASNT Recommended Practice No.
, , , , , , ., 40-41
and leak testing " " " " " " " " " ' "
.... ,,,.80
and liquid penetrant testing, ,
' , .. , , , . ,
Society of the Plastics Industry (SPI), vessel acoustic
emission testing procedure """"
, ' , , , , , , , " 310.311,317
Societies that issue acoustic emission standards
299
Solid state cameras ' , , . , . , , ..... , .' . .. " " ' " " , . . 178-180
Solid state image amplifiers
, ' , . , . , , ... , ... ' .. ' . . . 458
Solid state imaging devices ' , , , , ,
' ,,,,,,,,.
' , , , " 471
Solvent removable penetrants . .
' , ' , . , , , , , , . .. 82. 85-86
Solvent removers, use in liquid penetrant testing ... ' . ,
82
Sonic-ultrasonic methods
' , , , . , " 16
See also Acoustic nondestructive testing methods
.. , 212-217
Sorting, eddy current techniques for', .. ,
21-22
Sound units " " " " " " " " " " " "
Sources. See Radiographic isotope sources
South poles .. ..
..
' " , .. . .. ..
.. .. .. ... 267
Spallation ."""
",.,
", .. " " , " " , . " ' . , . , , . 98
Special methods of nondestructive testing .... , . , , ,
,. 473-513
Speckle techniques .,
".""
'" .. ".,
,.,. 498
Spectrum, electromagnetic . , , , . , , , . , , , . ' , '" , , , , " 92, 434, 480
Spindles (automotive), eddy current testing """.".,., 236-237
INDEX I 579'
Spot welding, acoustic emission monitoring
323-330
Springs, pickling cracks in
265
Standard physical leaks . . . . . ..
49
Standards, cost of inadequate
14
Standoffs. . . . . . . . . . . . . . . . . . . . . . .. .
401
Static electricity, hazards with flammable materials
. . . . .. 44
Static leak testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 36, 37
Steady state heat conduction
478,479
Steam powet' plants, borescope application
4.53,461
Steel
ball bearings. magnetic flux leakage testing . . . . . . . . . . . . . . . . . .. 245
bar inspection systems
218-222
bolt hole eddy current testing
. . . . . . . . . . . . . .. 231
discontinuities of . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 259-266
eddy current testing. . . . . . . . . . . . . . . . . . . . .
214, 215, 218-227
high temperature . . . .
. . . . . . . . . . . . . . . . . . . . . .. 223-227
free machining
260
grain size discontinuities . . . . . . . . . . . ..
..
413-414
pipe walls, remote field eddy current testing of
209-210
radiography .. . . . . . . . . . ..
145. 146. 1.50. 1.53. 1,54, 1.56
contrast.
..
165
films for
.........
. . . . . . . . . . . . . .. 1058, 159, 160, 161
radioscopy . . . . . . . . . . . . . . . . . . . . . . .
. .. 185
spot weld acoustic emission monitoring
. . . .. .... 327-329
thermography . .
.......................
495-496
ultrasonic beam attenuation bv
392
See alyo Ferromagnetic materials
Stefan-Boltzmann Law
.
480-481. 483
Stepping pipe crawlers
"
465
.. .. .. ..
6.5-69
Stot'age tanks, leak testing ....
Straight beam pulse echo ultrasonic testing
.. 382-396
Straightening cracks
.
.. ....... 264
Strain
.
475,477
. ........ 508
Strain gage transducers.
Strain measurement ..
474.497-500
resistance strain gaging
..... 506-508
................................. 475
Stress
246, 266
Stress corrosion cracking
............... 63
acoustic leak characteristics
ultrasonic imaging of
.
406
See also Crack detection
Stress cracking
.
266
Stress engineer
.
12
Stress measurement
474, 505
Stress response
.
16. 17
Stress wave emission. See Acoustic emission
Stress wave factor technique
506
Stringers
...................
. . . . .. 260
Strobe lighting
. . . . . . . . . . .. 426-427, 469-470
Structural flaws
16, 17
Structure determination
........
.
16, 17
Structured lighting
.
, . . . . . . . . . . . . . . . .. 469
Subject contrast, in radiography
164, 165
Submarines, autonomous
465
Subsurface discontinuities ..
. . . . . . . . . . . .. 271
Subterranean surveys
492
Subtraction operations, in radioscopic image enhancement ... 185
Summation operations, in radioscopic image enhancement 184-18.5
Supersonic reflectoscope
~
'
349
Surface coil eddy current transducers
204
Surface comparators
444
Synchrotrons . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. .. 106, 107
System Internationale (SI) units. See Sl units
T
Tap testing
,..................................... 50',
Targets, X-ray tubes
101-10;"2
'Iear diseontinuities
262,2(':)
Television camera tubes
4b;Z
Tele~ion holography
, . . . . .. 4~~
Television systems
radioscopy application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 178-1 s:
, remote positioning and transport systems .. . . . . . . . . . . . . . .. 465·467
. 1I.resolutton
: . .. .
,.,.... 463-46-;,
scanning prill.~pJes ,
, . . . . . . . . . . . . . .. .
461-462
underwaterlamps for
464
visual testing application
. . . . . . . . . . . . . . . . . . . . . . .. 458-459
Testing
,
" 9. It
See also Nondestructive testing
Thermal testing
16, 478
thermal vs. infrared
.... ....
.
47&
See also Infrared thermography
Thermal diffusivity . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . .. 479
Thermal transfer imaging system
49:3
Thermoelectric techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 212
Thermography. See Infrared thermography
Thermoluminescent dosimeters
. . . . . . . . . . . . . . .... 112. 12";'
Thickness gages
13.364.365,368-36'
Thickness measurement, by ultrasonic testing
347,352
Three-phase full-wave alternating current
282
Three-phase full-wave direct current . .
.. .. 282-28:3
Throughput, vacuum systems . . . . . . . . . .
. . . . . . . . . . . 55
Through-transmission ultrasonic testing 351. 352, 354-356. 3.57, 396
Thulium-HO
.
, .. 115.118
Time-of-flight measurements
411,419-420
Timing section, ultrasonic testing equipment
365
Titanium bolt holes, eddy current testing . . . . . . . . . . . . . . . . . .. 231
Tolerance specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 13
Tomography, X-ray computed. See X-ray computed tomography
Toxic gases
. . . . . . . . . . . . . . . . . . . . . . . . . 43
Trace ....
........
461. 462
Tracer probe techniques
34-35, 36, 48-49
safety aspects . . . . . . . ..
. . . . . . .. 45
Training
acoustic emission testing
........
302
leak testing .. . . . . . .
40-41. 43
liquid penetrant testing.
. . . . . . . . . . . . . . . . . . . .. 80
ultrasonic testing . . . . . . . . . . . . . . .. ..
346
visual testing
. . . . . . . . . . . . . . . . . . . . . . . . . . 441
Transformers, for X-ray generators
106
Transient heat transfer
,,,
, . . . . . . . . . . . . . . . .. 478-479
Transmit-receive method, of eddy current testing
203
Transmit/receive switch, ultrasonic testing equipment
. . . . . 365
Transmittance . . . . . . . . . . .. .. . . . . . . . . . . . . . . . . . .
. .. , . 21
Transverse discontinuity inspection, by magnetic flux
leakage testing
.
250-251
Tube gamma
.
180, 181
Tubes
angle beam contact ultrasonic testing
..........
. .. 398
boiler. visual testing ..... , . . . . . . . . . . . . . . . . . . . . . . . . . .. 4053. 461
composite. immersion ultrasonic testing .. . . . . . . . . . . . . . . .. 420-422
magnetic flux leakage testing
.
, . . . . . .. . 250-251
remote field eddy current testing of walls
206. 207-211
See also Pipes
;80 / INDEX
luhulation pinehwelds, on undersea repeaters, acoustic
emission testing .... . . . . . . . . . . . . . . . . . . . . . . . . . .. ... 334·336
iuekerman resistance strain gage
,:........... 506
iurbines
blades, X.ray computed tomographic evaluation
190. 191, 195
rotor wheels, immersion ultrasonic testing of ,., .. , . ,
414-418
)'pe 1 radiographicexposure devices
120-122
iype2 radiographic exposure devices
120-122
Ultrasonic wave propagation
. 349
Ultraviolet borescopes . , .. , . , . . . . . .. .
,.......... 452
Ultraviolet light,
, . . .. . .. ,. .
,. 92. 434. 435
hazards
437-438
Ultraviolet lighting. , .. ,
, .. .
,." .. ,............. 470
Undercut
146. 148. 150
Underground storage tanks, leak testing
65
Undersea electronic repeaters, acoustic emission testing .. 331-336
J
Units. See 51 units
Uranium
absorption curves
gamma radiography shielding material
Underwriters Laboratories ..
i-core eddy current probes
,,.,
., . . .. 204
ltimate strength
, . , .. , . . . . . . . . . . . . . . . . .. ,266
'rasonie attenuation
, , . " 350
. scattering
,
,,
,
, .. , ,. 392-393
'~ .sOni,C leak deteCtiOn"
, .. , . , . " .. , . . . 61,-62
JI sonic lenses
,
, . . . . . . . . . . .. 390-392
JI .onic pulse echo testing
,
351. 352. 356-357, 360
(Iba:es/disadvantages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 380
, J'1pff~.I>c',. .dia for
.
, .. , , . . . .. 400-403
focused beam immersion testing
, . . . . . . . . . . . . . . 390-392
imaging procedures
,
. . . . . . . . . . . . . . . . .. 404-406
straight beam tests
,." 382-396
applications " .. ,.,.,............................. 384·388
test frequency selection .,......
. .... , . . . . . . . . . 393-394
See also Immersion ultrasonic testing
Jltrasonie reflection techniques
size limitations . . . . . . . . . . . . . . . . . . . . . . . . . .. .,......... .. 13
Jltrasonie testing .. ,................................. 345-424
advantages
,.,
, .. , , , ., 346-347. 352
applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 347
A-scan presentation
........
356-358, 380, 381. 392, 39.5
B-sean presentation
356.358-359,380.381.395
calibration,
,..
, . . . . . . . . . . . . . . . . . .. 359-361
criteria for successful . .
348
C-scan presentation "
, . . . . . . . . . .. 356, 3,59. 380-381. 395
equipment for . . . . . . . .
, . . . . . . .. 363-369
gated system display
,............
356, .359
immersion method. See Immersion ultrasonic testing
.
.
large testing systems ..
369
laser application
, , . . . . . . . . . . . . . . . . . . . . . . . . . 370-371
limitations . . . . . . . . . .
252. 347-348
portable systems . . . . . . . . . . . . . . . . . . . .
364-366
pulse echo. See Ultrasonic pulse echo testing
..
.
,.".
361-362
system parameters
through-transmission systems
3.51, 352. 354-3,56. 357, 396
transmission cs, reflection techniques
3451
See also Acoustic nondestructive testing methods; Sonic-ultrasonic
methods
402
Jltrasonic testing couplants .. . . . . . . . . . . . . . . . . . . . . . .
Jltrasonic transducers
,
,
. . . . . . . . . . .. 3,52-354. 365
air-coupled
,
,
371-372
electromagnetic acoustic transducers (EMATs)
373·374
focused .. .. .
,...
,
390,391-392
high frequency
, . . . . . . . . 372-373
low frequency
,,
,
3i!·372
in straight beam testing . . . . . . . . . . . . . . . . . . . . . . . . . .. 382. 388-389
near neld ,
,................................. 389
wheel transducers
"" .. ,............... 409
Jltrasonic transducer shoes . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 400
0
•••••••••••••••••••.
,
,,
~
•
•
.••
•
•
•
•
••
'(
96
" . . . . . .. 122
v
Vacuum
,
,
,
,
54
Vacuum box bubble leak testing . . . . . . . . . . . . . . . . . . . . .. 58, 66-67
Vacuum box liquid penetrant leak testing . "
66-67
Vacuum box penetrant developer leak testing. . . . . . .. ..,.... 67
Vacuum systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. ,52. 54
leakage rate/testing ..... ' . . . . . . . . . . . ..
28. 35. 52·53. ,55·56
pressure measurement in
52
Vacuum ultraviolet
,
, , .. , . . . . . . . . . . . .. 437
Vacuum vessels, acoustic emission testing
312
Validity, of tests
,.................................. 14
Van de Graaff generators .. ,.,...
, . , . . . . . . . . . . .. 106. 107
Vaporproof borescopes
.. . . . . . . . . . . . . . .. 452
Ventilation, in leak testing .. ,........
' , . . . . . . . . . . .. 43-44
Verification test
,
,............ .51-52
Vessels. See Pressure vessels; Vacuum vessels
............. 505
Vibration analysis
,
.
Video
. . . . . . 459·461, 466
.
.
borescopes
..
498
holography
.
........... 482·483
radiometry
.
,
,
457-464
svsterns ...... ,
466-467
remote positioning/transport .,
.
See also Television svstems
tape recorders
.
'........
183
radioscopy application
.
visual testing application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 466
Vidicon cameras/tubes
. . . . . ..
179. 180. 181
visual testing application
,
, , ,. 4.58-459. 462. 470-471
X-ray sensitive . . . . . . . . . . .. ,
,............... 182
182
Vignetting . . . . . . . . . . . . . . . . ..
Villard circuit, X-ray generators . . . . . . . . . . . . . . • . . . . . . .. 104. 105
Virgin curve ......................,.............,......, 278
Visible light . . . . . . . . . . . . .
.
, .,.......... 92
Visible penetrants
81
,.....
, , . . . . . . . ..
428-429
Vision
blind spot
,
,.............. 430
color ,. ..
. .. ,
, . . . . . . . .. 432-434
peripheral
.
, . , . . . . .. 432
texture/reflection and
440
,
..,.... 429-430
Vision acuity
vision acuity examinations
430-431,432,441
Visual aids ,......................................... 440-448
Visual angle
,
,
"
, .. ,
,.,
,.... 432
INDEX I S3T
Visual testing
, . .. .
environmental factors
, "" .. ,.
.,
425-472
440-441
447-448.468
image enhancement
lighting. See Lighting
machine vision technology
", 468-471
photographic techniques for
. 446-447
remote positioning/transport systems .".,.,.,
. 465·467
. 435-439
safety aspects . .
,.
. . 441-443
test object effects
, , , .. ,
.
video technology application
457·464
See also Optical testing
. . . . . . . .. 190
Volume computed tomography "
Volume units
" 20
V.path ... , ", .. ,
. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 398. 405
w
Water, as ultrasonic testing couplant . , , , , , .
See also Immersion ultrasonic testing
Water cooled borescopes
..
. 452
Water cooled eddy current probe transducer
224
'Vatel" jet devices, for immersion ultrasonic testing .......... 409
Waterproof borescopes .
452
.
Water soluble penetrant developers
.
..
82e83
Water suspendible penetrant developers
.......... 83
Water washable penetrants
81. 84. 86
.............
400
Wedge shaped shoes
Welder's flash .... , .".
437
Welds
4L5
aircraft rotor wheels. immersion ultrasonic testing. . . . . . . . . . . .
angle beam contact ultrasonic testing of .
398,399. 404·406
discontlnuities
'
. . . . . . . . . . . . . . . . . . . .. 263
leak testing of . . . . . . . . .
28-29. 50. 52-55
in pipes, remote field eddy current testing. . . . . . . . . . . . . . .. Z08. 210
322-330
resistance spot welds, acoustic emission monitoring of . . . .
thermography . . . . . . . . . . . . . . . . . . . . . . . . . . . .
, ,494~495
Well casings
242·243. 252-253
magnetic flux leakage testing
remote field eddy current testing
206, 211
.
174
Willemite . . . . . . . . .
Wet method magnetic particles. .
.
, 289. 290. 291
Wheel transducers
. . . . . . . . . ..
. . . . . . . . .. 409
Whittemore resistance strain gage
506
Wide field borescopes
.......... ..............
452
Wide field macroscopes .
......... .....
446
Wide field tubes .........
.
, .. .. 445,446
Wien's Displacement Law
.
481,482
Wire penetrameters
.
166-169
Wire rope, magneti~ flux leakage testing . ,
242. 243. 251~252
x
X-ray computed tomography
,. 188-191
advantages/disadvantages ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 190
applications
, , , , , , . , .. , . . . . . . . . .. 188, 195-196
sensitivity .. .
,
, 191-195
system components .".""......................... 191, 194
,.,,
,. .
, 15>1
X-ray diffraction mottling
X.ray equivalency
. . . . . . . . . . . . . . . . . . . . . . . . .. 144-1'45
X-ray e:l:posure
e :posure charts.. .
,
110,159-161
e"':posure factor ,
, , , , , , , . . . . . . . . . . ..
141·14-2
See also Radiographic e"posure devices
X-ray fluorescence specITometry . . . . . . . . . . . . . . . . . . . . . . . . .. 474;
X-ray generators
,
".,.....
. . . . . . . . . . . . . . . . .. 99'
',..... base{ille information
,
""".,. no.
cirdUltsJor", . , , .. , . , . , ,
104, 105
.
108-109
control
.....................
high energy,sources for
103-108
kilovoltage'adjustment """"
. . . . . . . . . . . .. 108-109
maintenance
",.,.,.,., .. " III
milliamperage adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 109
operation
".".
1I0·1l3
safety aspects
,. 112-113
sources for, See Radiographic isotope sources
1I0-Hl
unit selection
See also Radiography
X-ray image intensifiers, ., , " .
175-177,181
X-ray nondestructive testing. See Radiography
X.radiography. See Radiography
.
Xvrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .
absorption
generation . " " " .
scattering . . . . . . . . . . . . . . . . . . .
X-my safety
..
X-ray sensitive vidicon cameras .
X-ray surveys
survey equipment
",..
X-ray tubes
emission from
rnicrofocus. for radioscopy
.. 92-93
95-98. 144-14.3
...........
.. 93-94
..................
146
. . . . . . . . . . . . . . . . . . . . . . . . .. 113
. . .. "'" .
182
113
. , . .. 123-127
, ., 99-103
. . . . . . . . . . . . . . . . . . . .. 133. 134
, .. , ,
.. 175
y
Yield point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 477
Yoke demagnetization
286
Yokes
, 277
z
Z (atomic number), dependence of photon absorption on .,. 97-98
Zero liftoff impedance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 204
Zirconium, radiation absorption by
Zone lenses
..,
,
.., .. ".... 94
390-391
