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Stainless Steel Cleaning & Passivation Standard Practice
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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. Designation: A380/A380M − 17 Standard Practice for Cleaning, Descaling, and Passivation of Stainless Steel Parts, Equipment, and Systems1 This standard is issued under the fixed designation A380/A380M; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revis revision. ion. A number in parentheses parentheses indicates the year of last reapproval. reapproval. A superscript epsilon (´) indicates an editorial change since the last revision or reapproval. This standard has been approved for use by agencies of the U.S. Department of Defense. 1.1.1.2 1.1.1. 2 Pas Passiv sivatio ation n is rem remova ovall of exo exogen genous ous iro iron n or iro iron n compounds from the surface of a stainless steel by means of a chemica che micall dis dissol soluti ution, on, mos mostt typ typica ically lly by a trea treatme tment nt wit with h an acid solution that will remove the surface contamination but willl not sig wil signifi nifican cantly tly af affec fectt the sta stainle inless ss stee steell itse itself. lf. Thi Thiss process is described in a general way in 6.2.11 and defined precisely in 6.4 with further reference to the requirements of Annex A2 and Part II of the table on acid cleaning of steel. Unless otherwise specified, it is this definition of passivation thatt is tak tha taken en as the meaning meaning of a spe specifie cified d req requir uireme ement nt for passivation. passiv ation. (See also Specific Specification ation A967/A967M A967/A967M.) .) 1.1.1.3 1.1.1 .3 Passiv Passivation ation is the chemical treatment of a stainless steel with a mild oxidant, such as a nitric acid solution, for the purpose of enhancing the spontaneous formation of the protectivee pa tiv pass ssiv ivee met metal al ox oxid idee fil film. m. Su Such ch ch chem emica icall tr treat eatme ment nt is generally not necessary for the formation of the passive metal oxide film. 1.1.1.4 1.1.1 .4 Passiv Passivation ation does not indicate the separate process process of descaling as described in Section 5 5,, although descaling may be necessary before passivation can be effective. Depending on the application, chemical descaling (acid pickling) as described in 5.2.1 may pro provid videe suf suffficie icient nt pas passiv sivatio ation n as defi defined ned in 1.1.1.2.. 1.1.1.2 1. Sco Scope* pe* 1.1 This practice covers recommendations recommendations and precau precautions tions for cleaning, descaling, and passivating of new stainless steel parts, par ts, asse assembl mblies ies,, equ equipm ipment ent,, and ins install talled ed sys systems tems.. The These se recommendati recomm endations ons are presen presented ted as proce procedures dures for guida guidance nce when it is recognized that for a particular service it is desired to remove surface contaminants that may impair the normal corrosion resistance, or result in the later contamination of the particular stainless steel grade, or cause product contamination. The selection of procedures from this practice to be applied to the pa the part rtss ma may y be sp spec ecifie ified d up upon on ag agre reem emen entt be betw twee een n th thee supp su ppli lier er an and d th thee pu purc rcha hase serr. Fo Forr ce cert rtai ain n ex exce cept ptio iona nall applications, additional requirements which are not covered by this practice practice may be spe specifi cified ed upo upon n agr agreeme eement nt bet betwee ween n the supplier and the purchaser. Although they apply primarily to materials in the composition ranges of the austenitic, ferritic, martensitic, martens itic, and duple duplex x stainles stainlesss steels, the practic practices es descri described bed may also be useful for cleaning other metals if due consideration is given to corrosion and possible metallurgical effects. 1.1.1 The term passivation passivation is commo commonly nly applied to several distinctly different operations or processes relating to stainless stee st eels ls.. In or orde derr to av avoi oid d am ambi bigu guit ity y in th thee se sett ttin ing g of requirements, it may be necessary for the purchaser to define precise pre cisely ly the int intend ended ed mea meanin ning g of pas passiv sivatio ation. n. Som Somee of the various meanings associated with the term passivation that are 1.2 This practice does not cover decontaminatio decontamination n or cleaning of equipment or systems that have been in service, nor does in common usage include the following: 1.1.1.1 1.1.1 .1 Passiv Passivation ation is the process by which a stainles stainlesss steel will spontaneously form a chemically resistant surface when exposed to air or other oxygen-containing environments. It was at one time considered that an oxidizing treatment was necessary to establish this passive metal oxide film, but it is now accepted that this film will form spontaneously in an oxygencontaining contain ing environment environment provi providing ding that the surfa surface ce has been thoroughly cleaned or descaled. it cover descaling and cleaning of may materials at the mill. the other hand, some of the practices be applicable forOn these purposes. purp oses. While the practic practicee provi provides des recomm recommendati endations ons and information concerning the use of acids and other cleaning and descaling agents, it cannot encompass detailed cleaning procedure du ress fo forr sp speci ecific fic ty type pess of eq equi uipm pmen entt or in inst stall allati ation ons. s. It therefore in no way precludes the necessity for careful planning and judgment judgment in the sele selectio ction n and implement implementatio ation n of suc such h procedures. 1.3 The These se pra practic ctices es may be app applied lied when free iro iron, n, oxi oxide de scale, rust, grease, oil, carbonaceous or other residual chemical films, film s, soi soil, l, par particl ticles, es, met metal al chip chips, s, dir dirt, t, or oth other er non nonvol volatil atilee deposits depos its might adversely affect affect the metallu metallurgic rgical al or sanitar sanitary y condition or stability of a surface, the mechanical operation of a part, component, or system, or contaminate a process fluid. 1 This practice is under the jurisd jurisdiction iction of ASTM Committee A01 on Steel Steel,, Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee A01.14 on Methods of Corrosion Testing. Current edition approved Sept. 1, 2017. Published September 2017. Originally approved in 1954. Last previous edition approved in 2013 as A380/A380M – 13. DOI: 10.1520/A0380_A0380M-17. The degree of cleanness required on a surface depends on the *A Summary of Changes section appears at the end of this standard Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States 1 A380/A380M − 17 application. In some cases, no more than degreasing or removal of gro gross ss con contam taminat ination ion is nec necess essary ary.. Oth Others ers,, suc such h as foo fooddhandli han dling ng,, pha pharma rmaceu ceutic tical, al, aer aerosp ospace ace,, and cer certai tain n nu nucle clear ar applications, may require extremely high levels of cleanness, including includ ing removal of all detectable residual chemical films and contaminants that are invisible to ordinary inspection methods. F22 Test Meth Method od for Hyd Hydrop rophob hobic ic Sur Surfac facee Fil Films ms by the Water-Break Test 2.2 ISO Standards:3 ISO 14644-1 Cleanrooms and associated controlled environments -- Part 1: Classification of air cleanliness by particle concentration ISO 14644-2 Cleanrooms and associated controlled environments men ts -- Pa Part rt 2: Mo Moni nito tori ring ng to pr prov ovid idee ev evid iden ence ce of cleanroom performance related to air cleanliness by particle concentration NOTE 1—The term “iron,” when hereinafter referred to as a surface contaminant, shall denote free iron. contaminant, 1.4 Att Attain ainmen mentt of sur surfac faces es that are fre freee of iro iron, n, meta metallic llic deposits, and other contamination depends on a combination of properr design prope design,, fabri fabrication cation methods, cleaning and descali descaling, ng, and protection to preve prevent nt recon recontaminati tamination on of cleaned surfaces. surfaces. Meanin Mea ningfu gfull test testss to est establi ablish sh the degree of clea cleanne nness ss of a surface are few, and those are often difficult to administer and to eva evalua luate te obj objecti ectivel vely y. Visu isual al ins inspec pection tion is sui suitab table le for the detection of gross contamination, scale, rust, and particulates, but may not reveal the presence of thin films of oil or residual chem ch emica icall film films. s. In ad addi ditio tion, n, vi visu sual al in insp spect ectio ion n of in inter terna nall surfaces is often impossible because of the configuration of the item. Methods are described for the detection of free iron and transparent chemical and oily deposits. 3. Desig Design n 3.1 Con Consid sidera eratio tion n sho should uld be giv given en in the design of par parts, ts, equipment, and systems that will require cleaning to minimize the pre presen sence ce of cre crevic vices, es, poc pockets kets,, blin blind d hol holes, es, und undrain rainable able cavities, and other areas in which dirt, cleaning solutions, or sludge slu dge might lod lodge ge or bec become ome tra trappe pped, d, and to pro provid videe for effec ef fectiv tivee cir circula culatio tion n and rem remova ovall of clea cleanin ning g sol solutio utions. ns. In equipment and systems that will be cleaned in place or that cannot be immersed in the cleaning solution, it is advisable to slope lines for drainage: to provide vents at high points and drain dr ainss at lo low w po poin ints ts of th thee ite item m or sy syst stem em;; to ar arra rang ngee fo forr removal or isolation of parts that might be damaged by the cleanin clea ning g sol soluti ution on or fum fumes es fro from m the clea cleanin ning g sol soluti utions ons;; to provid pro videe mea means ns for atta attachi ching ng temp tempora orary ry fill and cir circula culatio tion n lines; and to provide for inspection of cleaned surfaces. 1.5 This practice provides definitions definitions and descr describes ibes practices for cleaning, descaling, and passivation of stainless steel parts. par ts. Test estss with acc accepta eptance nce cri criter teria ia to dem demons onstrat tratee tha thatt the passivation passiv ation procedures procedures have been successful successful are listed in 7.2.5 and 7.3.4 7.3.4,, an and d can al also so be fo foun und d in Sp Speci ecific ficati ation on A967/ A967M.. A967M 3.2 In a co 3.2 comp mple lex x pi pipi ping ng sy syst stem em it ma may y be di diffficu icult lt to determine how effective a cleaning operation has been. One method of designing inspectability into the system is to provide a sh shor ortt fla flang nged ed len lengt gth h of pipe (that (that is is,, a sp spoo ooll pi piece ece)) at a location where the cleaning is likely to be least effective; the spool piece can then be removed for inspection upon completion of cleaning. 1.6 The values stated in either SI units or inch-pound inch-pound units are to be regarded separately as standard. The values stated in each system may not be exa exact ct equ equiva ivalen lents; ts; the theref refore ore,, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. 1.7 This standar standard d doe doess not purport purport to add addre ress ss all of the safet sa fetyy co conc ncer erns ns,, if an anyy, as asso socia ciate ted d wit with h its us use. e. It is th thee responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. (For more specific 4. Precle Precleaning aning safety precautions precautions see 7.2.5.3 7.2.5.3,, 7.3.4 7.3.4,, Section 8, A1.7 A1.7,, and A2.11..) A2.11 1.8 This int intern ernati ationa onall sta standa ndard rd was dev develo eloped ped in acc accor or-dance with internationally recognized principles on standardizatio iza tion n es esta tabl blis ishe hed d in th thee De Decis cisio ion n on Pr Prin incip ciple less fo forr th thee Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. Material Mater ialss are us usua ually lly pr precl eclean eaned ed be befo fore re ho hot-f t-for ormin ming, g, anneali ann ealing, ng, or oth other er hig high-t h-temp empera eratur turee ope operat ration ion,, bef before ore any descaling operation, and before any finish-cleaning operation wher wh eree th thee pa parts rts wi will ll be imm immer erse sed d or wh wher eree th thee cl clean eanin ing g solu so lutio tions ns wi will ll be re reus used ed.. It Item emss th that at ar aree su subj bjec ectt to se seve vera rall redraws or a series of hot-forming operations, with intermediate anneals, shall be cleaned after each forming operation, prior to ann anneali ealing. ng. Pre Precle cleanin aning g may be acco accompl mplish ished ed by vap vapor or degreasing; immersion in, spraying, or swabbing with alkaline or emulsi emulsion on cleane cleaners; rs; steam; or highhigh-press pressure ure water-jet (see 6.2). 6.2 ). 4.1 Preclea Precleaning ning is the removal of grease, grease, oil, paint, soil, grit, and oth other er gro gross ss con contami taminati nation on pre prepar parato atory ry to a fab fabrica ricatio tion n process or final cleaning. Precleaning is not as critical and is generally not as thorough as subsequent cleaning operations. 2. Referenc Referenced ed Documents Documents 2.1 ASTM Standards:2 A967/A967M Specification for Chemical Passivation Treatments for Stainless Steel Parts F21 Test Met Method hod for Hyd Hydrop rophob hobic ic Sur Surfac facee Film Filmss by the Atomizer Test 5. Desc Descaling aling 5.1 General—Des Descali caling ng is the rem remova ovall of hea heavy vy,, tig tightl htly y adhere adh erent nt ox oxide ide film filmss res result ulting ing fr from om hot hot-fo -form rming ing,, hea heatttreatment, treatme nt, weldin welding, g, and other high-temperatur high-temperaturee operat operations. ions. 2 For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [email protected]. For Annual Book of ASTM Standards volume information, refer to the standard’s Document Summary page on the ASTM website. 3 Availab vailable le from Intern Internationa ationall Orga Organizati nization on for Stan Standardiz dardization, ation, ISO Centr Central al Secretariat, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva, Switzerland. 2 A380/A380M − 17 Because use mil milll pro produc ducts ts are usu usually ally supplied supplied in the des descale caled d Beca condition, descaling (except removal of localized scale resulting from welding) is generally not necessary during fabrication of equipment or erection of systems (see 6.3 6.3). ). When necessary, scale may be removed by one of the chemical methods listed below, by mechanical methods (for example, abrasive blasting, sanding, sandin g, grinding, power brushing), brushing), or by a combi combination nation of these. tions (such as the presence of crevices). If used, neutralization is usually also followed by rinsing with clean water to remove all tra traces ces of the neu neutral tralizin izing g age agent nt and tho thorou rough gh dry drying ing.. To mini mi nimiz mizee sta stain inin ing, g, su surf rfac aces es sh shall all no nott be pe perm rmitt itted ed to dr dry y betwee bet ween n suc success cessive ive step stepss of the acid des descali caling ng and rin rinsin sing g procedure (see A1.5 A1.5). ). 5.2.6 Chemical descaling methods, factors in their selection, and an d pr prec ecau autio tions ns in th their eir us usee ar aree de desc scri ribe bed d in th thee Metals Handbook.4 When chemical descaling is necessary, it should 5.2 Chem Chemical ical Des Descali caling ng (Pic (Picklin kling)— g)—Chem Chemical ical desc descalin aling g agents include aqueous solutions of sulfuric acid, or nitric and hydrofl hyd rofluor uoric ic acid acids, s, as des describ cribed ed in Anne Annex x A1 A1,, Tab Table le A1.1 A1.1,, molten alkali or salt baths, and various proprietary formulations. The safety precautions of 8.6 shall be observed in the use of the these se meth methods ods.. Par Particu ticular lar car caree sha shall ll be exe exercis rcised ed whe when n pickling pick ling closed sys systems tems and item itemss wit with h cre crevic vices es or int intern ernal al voids to prevent retention of pickling solutions and residues. 5.2.1 Acid Pick Nitricric-hyd hydrofl rofluor uoric ic acid sol soluti ution on is Pickling ling— —Nit most widely used by fabricators of stainless steel equipment and rem remove ovess bot both h met metalli allicc con contam tamina ination tion,, and weld welding ing and heat-treating scales. Its use should be carefully controlled and is not recommended for descaling sensitized austenitic stainless steels or hardened martensitic stainless steels or where it can com comee into contact contact wit with h carb carbon on ste steel el par parts, ts, ass assemb emblies lies,, equipment, and systems. See also A1.3 A1.3.. Solutions of nitric acid be done while thefabrication part is in its possible geometry, before subsequent or simplest installation steps create internal cre crevic vices es or und undrai rainab nable le spa spaces ces tha thatt may trap descaling descaling agents age nts,, slu sludge dge,, par particl ticles, es, or con contam tamina inated ted rin rinse se wat water er that might either result in eventu eventual al corro corrosion sion or adver adversely sely affect affect operation of the item after it is placed in service. alone are usually not effective for removing heavy oxide scale. 5.2.2 Surfa Surfaces ces to be descale descaled d shall be precleaned to remove oils and greases prior to acid treatment (see A1.5 A1.5)), and are usually precleaned prior to other chemical treatments. 5.2.3 When size and shape of product permit, permit, total immersion in the pickling solution is preferred. Where immersion is impractical, impract ical, descaling may be accomp accomplished lished by ( 1) wetting the surfaces by swabbing or spraying, or ( 2) by partially filling the item with picklin pickling g solution and rotating or rocki rocking ng to slosh the solutio sol ution n so tha thatt all sur surfac faces es rec receiv eivee the req requir uired ed che chemica micall treatment. The surface should be kept in contact with agitated solution for about 15 to 30 min or until inspection shows that comp co mplet letee sca scale le rem remov oval al ha hass be been en acc accom ompl plish ished ed.. With ithou outt agitation, additional exposure time may be required. If rocking or rotation are impracticable, pickling solution may be circu- martensiti marten siticc sta stainle inless ss stee steels ls whe when n in the har harden dened ed con condit dition ion,, mechanical mechan ical descaling may be the only suitable method. Grinding is usually the most effective means of removing localized scale such as that which results from welding. Disadvantages of mec mechan hanical ical des descali caling ng are cos cost, t, as com compar pared ed to che chemica micall descaling, and the fact that surface defects (for example, laps, pits, slivers) may be obscured, making them difficult to detect. 5.3.1 5.3 .1 Sur Surfac faces es to be descaled descaled may have to be pre preclea cleaned ned.. Particular care must be taken to avoid damage by mechanical methods when descaling thin sections, polished surfaces, and closeclo se-tol toleran erance ce par parts. ts. Aft After er mec mechan hanical ical des descali caling, ng, sur surfac faces es shou sh ould ld be cl clean eaned ed by scr scrub ubbi bing ng wi with th ho hott wa water ter an and d fib fiber er brushes, followed by rinsing with clean, hot water. 5.3.2 5.3 .2 Gri Grindi nding ng whe wheels els and san sandin ding g mate materia rials ls sho should uld not contain iron, iron oxide, zinc, or other undesirable materials lated through the item or system until inspection shows that descaling has been accomplished. 5.2.4 Over Over-pick -pickling ling must be avoid avoided. ed. Uniform removal of scale sca le wi with th ac acid id pi pick cklin ling g de depe pend ndss on th thee aci acid d us used ed,, ac acid id concen con centra tratio tion, n, sol soluti ution on tem temper peratu ature, re, and con contact tact time (se (seee Annex Ann ex A1 A1). ). Con Contin tinuou uouss exp exposu osure re to pic picklin kling g sol soluti utions ons for more than 30 min is not recommended. The item should be drained and rinsed after 30 min and examined to check the effective ef fectiveness ness of the treatment. Additional Additional treatme treatment nt may be required. Most pickling solutions will loosen weld and heattreating scale but may not remove them completely. Intermittent scrubbing with a stainless steel brush or fiber-bristle brush, in conjunction with pickling or the initial rinse, may facilitate thee re th remo mova vall of sca scale le pa part rticl icles es an and d pr prod oduc ucts ts of ch chem emica icall reaction (that is, pickling smut). that may cause contamination of the metal surface. Grinding wheels, sanding materials, and wire brushes previously used on other metals should not be used on stainless steel. Wire brushes shou sh ould ld be of a st stain ainle less ss st steel eel wh which ich is eq equa uall in co corr rros osio ion n resistance to the material being worked on. 5.3.3 5.3 .3 Clean, pre previo viousl usly y unu unused sed abr abrasiv asives, es, suc such h as gla glass ss beads or iron-free silica or alumina sand, are recommended for abrasiv abr asivee bla blastin sting. g. Ste Steel el sho shott or gri gritt is gen genera erally lly not rec recomommended because of the possibility of embedding iron particles. The use of stainless steel shot or grit reduces the danger of rusting and iron contamination, but cannot completely eliminate the possi possibility bility of embed embedding ding residues of ironiron-oxide oxide scale. 5.3.4 If a totally iron and scale free surface surface is required, required, most abrasiv abr asivee bla blastin sting g may be fol follow lowed ed by a bri brief ef acid dip (se (seee Annex A2) A2) or passivation treatment (see 6.4 6.4)). 5.3 Mechanical Descaling—Mechanical descaling methods include abrasive blasting, power brushing, sanding, grinding, and chi chippi pping. ng. Pro Proced cedura urall req requir uiremen ements ts and pre precaut caution ionss for some of these methods are given in the Metals Handb Handbook ook.4 Mechanical descaling methods have the advantage that they do not pro produc ducee suc such h phy physica sicall or che chemic mical al con conditi ditions ons as inte interrgranular granu lar attack, pitting, hydr hydrogen ogen embrittlement, embrittlement, cracks cracks,, or smut deposits. For some materials, in particular the austenitic stain st ainle less ss st steel eelss wh when en in th thee sen sensit sitize ized d co cond nditi ition on an and d th thee 5.2.5 After chemical chemical descaling, surfaces surfaces shall be thoro thoroughly ughly rinsed rinse d wi with th cl clean ean wa water ter to re remo move ve al alll tr trace acess of re resid sidua uall chemicals and thoroughly dried after the final water rinse. A neutralization treatment may be necessary under some condi- 4 “Surface “Surf ace Clean Cleaning, ing, Finis Finishing, hing, and Coati Coating,” ng,” Metals Handb Handbook, ook, Am. Soc. Metals, 9th ed., Vol 5, 1982. 3 A380/A380M − 17 6.2.2 Emulsio Emulsion n Cleanin Cleaning g is a pr proc oces esss fo forr re remo movi ving ng oi oily ly deposits and other common contaminants from metals by the use of com common mon or organ ganic ic sol solven vents ts dis disper persed sed in an aqu aqueou eouss solution with the aid of a soap or other emulsifying agent (an emulsif emu lsifyin ying g age agent nt is one which increases increases the stab stabilit ility y of a dispersion of one liquid in another). It is effective for removing a wi wide de va vari riety ety of co cont ntam amin inan ants ts in inclu cludi ding ng pi pigm gmen ente ted d an and d unpigme unp igmented nted draw drawing ing comp compoun ounds ds and lubr lubrican icants, ts, cutti cutting ng fluids,, and residues resul fluids resulting ting from liquid penetrant penetrant inspec inspection. tion. 6. Clea Cleaning ning 6.1 General—Cleaning includes all operations necessary for the removal of surface contaminants from metals to ensure (1) maximum corrosion resistance of the metal, (2) prevention of product contamination, and (3) achievement of desired appearance. Cleanness is a perishable condition. Careful planning is necessary to achieve and maintain clean surfaces, especially where whe re a hig high h deg degree ree of clea cleanne nness ss is req requir uired. ed. Selection Selection of cleaning processes is influenced mainly by the type of contaminant to be removed, the required degree of cleanness, and cost. If careful control of fabrication processes, sequencing of cleaning and fabrication operations, and measures to prevent recontamination of cleaned surfaces are exercised, very little spec sp ecia iall cl clea eani ning ng of th thee fin finis ishe hed d it item em or sy syst stem em ma may y be necessary to attain the desired level of cleanness. If there is a question questio n concer concerning ning the ef effective fectiveness ness of cleanin cleaning g agents or procedures, or the possible adverse effects of some cleaning agents or procedures on the materials to be cleaned, trial runs using test specimens and sensitive inspection techniques may be desira desirable. ble. Descriptions, Descriptions, processes, and precau precautions tions to be obse ob serv rved ed in cl clean eanin ing g ar aree gi give ven n in th thee Metals Hand Handbook book.4 Proprietary cleaners may contain harmful ingredients, such as chlorides or sulfur compounds, which could adversely affect the performance of a part, equipment, or system under service Emulsion cleaning is used when rapid, superficial cleaning is required and when a light residual film of oil is not objectionable. 6.2.3 Solvent Cleaning is a process for removing contaminants nan ts fro from m met metal al sur surfac faces es by imm immers ersion ion or by spr sprayi aying ng or swabbing with common organic solvents such as the aliphatic petroleums, chlorinated hydrocarbons, or blends of these two classes of solvents. Cleaning is usually performed at or slightly above abo ve roo room m temp temperat erature ure.. Exc Except ept for par parts ts with ext extrem remely ely heavy contamination or with hard-to-reach areas, or both, good agitation will usually eliminate the need for prolonged soaking. Virtually all metal can be cleaned with the commonly used solvents unless the solvent has become contaminated with acid, alkali, oil, or other foreign material. Chlorinated solvents are not recommended for degreasing of closed systems or items with crevices or internal voids. 6.2.4 V Vapor apor Degreasing is a ge gene neri ricc te term rm ap appl plie ied d to a cleaning process that employs hot vapors of a volatile chlorinated nat ed sol solven ventt to rem remove ove con contami taminan nants, ts, and is par particu ticular larly ly effective against oils, waxes, and greases. The cleanness and chemical stability of the degreasing solvent are critical factors in the efficiency of the vapor and possible chemical attack of the metal. Water in the degreasing tank or on the item being cleaned may react with the solvent to form hydrochloric acid, which is usually harmful to the metal. No water should be present in the degreasing tank or on the item being cleaned. Acids, oxidizing oxidizing agents agents,, and cyanides must be prevented from contaminating the solvent. Materials such as silicones cause foam fo amin ing g at th thee liq liqui uidd-va vapo porr in inter terfa face ce an and d may re resu sult lt in recontamination of the workpiece as it is removed from the degreaser. Vapor degreasing with chlorinated solvents is not recommended for closed systems or items with internal voids or crevic crevices. es. 6.2.5 Ultrasonic Cleaning is often used in conjunction with certain solvent and detergent cleaners to loosen and remove contaminants from deep recesses and other difficult to reach areas, are as, par particu ticularl larly y in smal smalll wor work-p k-piece ieces. s. Cavi Cavitati tation on in the liquid liq uid pro produc duced ed by the hig high h fre freque quency ncy sou sound nd cau causes ses micr micro o agitation of the cleaner in even tiny recesses of the workpiece, making the method especially desirable for cleaning parts or assemblies assemb lies havin having g an intric intricate ate config configuratio uration. n. For extremely high levels of surface cleanness, high-purity solvents (1 ppm total nonvolatile residue) are required. condition condit ions. s. It is reco recomme mmende nded d tha thatt the man manufa ufactu cturer rer of the cleaner be consulted if there is reason for concern. NOTE 2—Instances are known where stainless steel vessels have stress cracked crack ed be befo fore re st star artt-up up du duee to st stea eami ming ng ou outt or bo boil ilin ing g ou outt wi with th a chloride-containing detergent. 6.2 Cleanin Cleaning g Method Methods— s—Deg Degrea reasin sing g and gen genera erall clea cleanin ning g may be acc accomp omplis lished hed by imm immers ersion ion in, swa swabbi bbing ng wit with, h, or spraying with alkaline, emulsion, solvent, detergent, chelate, or acid cleaners or a combination of these; by vapor degreasing; by ultrasonics using various cleaners; by various mechanical methods meth ods;; by steam, with or with without out a clea cleaner ner;; or by hig highhpressure water-jetting. The cleaning method available at any given time during the fabrication or installation of a component or system is a function of the geometric complexity of the item, the type of contamination present, the degree of cleanliness requir req uired, ed, and cos cost. t. Met Method hodss com common monly ly use used d for rem removi oving ng deposi dep osited ted con contami taminan nants ts (as opp oppose osed d to sca scale) le) are des descri cribed bed briefly bri efly below and in gre greater ater detail (includin (including g fac factor torss to be considered consid ered in their selectio selection n and use) in the Metals Handbook4 and the SSPC Steel Structures Painting Handbook.5 The safety precautions precau tions of 8.6 sh shal alll be ob obse serv rved ed in th thee us usee of th thes esee methods meth ods.. Par Particu ticular lar care sha shall ll be exe exercis rcised ed whe when n clea cleanin ning g closed systems and items with crevices or internal voids to prevent retention of cleaning solutions and residues. 6.2.1 Alkaline Cleanin Cleaning g is us used ed fo forr th thee re remo mova vall of oi oily ly,, semisol semi solid, id, and sol solid id con contami taminan nants ts fro from m meta metals. ls. To a gre great at extent the solutions used depend on their detergent qualities for cleaning action and effectiveness. effectiveness. Agitation and temperature of the solution are important. 6.2.6 Synthetic Detergents are extensively used as surfaceactive agents because they are freer rinsing than soaps, aid in soils dispersion, and prevent recontamination. They are effective for softening hard water and in lowering the surface and interfacial interf acial tensions of the solutio solutions. ns. Synth Synthetic etic deter detergents, gents, in 5 Steell Struc Structures tures Painting Council, Vol Vol 1, 1982, Good Paint Painting ing Prac Practices tices,, Stee Chapters 2.0–2.9, 3.1–3.2. 4 A380/A380M − 17 particu ticular lar,, sho should uld be che checke cked d for the pre presen sence ce of har harmfu mfull par ingredients as noted in 6.1 6.1.. 6.2.7 Chelate Cleaning—Chelates are chemicals that form soluble, complex molecules with certain metal ions, inactivating the ions in solution so they cannot normally react with another element or ions to produce precipitates or scale. They enhance the solubility of scales and certain other contaminants, do not precipitate different scales when the cleaning solution becomes spent, and can be used on some scales and contami- shall not be permitted to dry between successive steps of the acid cleaning cleaning and rin rinsin sing g pro proced cedure ure.. Aci Acid d clea cleanin ning g is not recommended recomm ended where mechan mechanical ical cleanin cleaning g or other chemical methods will suffice on the basis of intended use and, as may be necessary, on inspection tests (see 7.2 and 7.3 7.3). ). Requirements for superfluous cleaning and inspection testing can result in excessive costs. Acid cleaning, if not carefully controlled, may damage the surface and may result in further contamination of the surface. 6.2.12 Rinsing—After cleaning with an aqueous chemical cleanin clea ning g sol soluti ution, on, sur surfac faces es sha shall ll be tho thorou roughl ghly y rin rinsed sed wit with h clean clea n wat water er to rem remove ove all tra traces ces of res residu idual al che chemica micals ls and thoroughly dried after the final water rinse. A neutralization treatment may be necessary under some conditions (such as the presen pre sence ce of cre crevice vices). s). If use used, d, neu neutra traliza lizatio tion n is usu usually ally als also o followed by rinsing with clean water to remove all traces of the neutralizing agent and thorough drying. (See A2.10 A2.10.) .) nants thatelating even acids willcon not attack. properly used use d (ch (chelat ing mineral agents age nts mus must t be contin tinuou uously sly When circul cir culated ated and must be maintain maintained ed within carefully controlled controlled temper temperature ature limits), intergranular attack, pitting, and other harmful effects aree min ar minima imal. l. Ch Chela elatin ting g ag agen ents ts ar aree pa part rticu icular larly ly us usef eful ul fo forr cleaning installed equipment and systems. 6.2.8 M Mechanica echanicall Cleanin Cleaning g (al (also so see 5.3 5.3)) — Abrasive blastin blas ting, g, vap vapor or bla blastin sting g usi using ng a fine abr abrasi asive ve sus suspen pended ded in water wa ter,, gr grin indi ding ng,, or wi wire re br brus ushi hing ng ar aree of often ten de desi sira rabl blee fo forr removing surface contaminants and rust. Cleanliness of abrasives and cleaning equipment is extremely important to prevent recontamination of the surfaces being cleaned. Although surfaces may appear visually clean follo following wing such proce procedures dures,, residual films which could prevent the formation of an optimum mu m pa pass ssiv ivee co cond nditi ition on ma may y st still ill be pr pres esen ent. t. Su Subs bseq eque uent nt 6.3 Cleaning of Welds and Weld-Joint Areas— Areas—The joint area and surrounding metal for several inches back from the joint prepar pre paratio ation, n, on bot both h fac faces es of the weld, sho should uld be clea cleaned ned immediately before starting to weld. Cleaning may be accomplis pl ishe hed d by br brus ushi hing ng wi with th a cle clean an sta stain inle less ss st steel eel br brus ush h or scrubbing with a clean, lint-free cloth moistened with solvent, or both. When the joint has cooled after welding, remove all treatment treatm ent suc such h as add additio itional nal iro iron-f n-free ree abr abrasi asive ve cle cleani aning ng methods, acid cleaning, passivation, or combinations of these is, therefore, required for stainless steel parts, equipment, and systems to be used where corrosion corrosion resistance resistance is a prime factor to sat satisf isfy y per perfor forman mance ce and ser servic vicee req requir uireme ements nts,, or whe where re product contamination must be avoided. 6.2.9 Steam Cleanin used d mos mostly tly for cleaning cleaning bul bulky ky Cleaning g is use objects obj ects that are too lar large ge for soak tan tanks ks or spr sprayay-was washin hing g equi eq uipm pmen ent. t. It ma may y be us used ed wi with th cle clean anin ing g ag agen ents ts su such ch as emulsions, solvents, alkalis, and detergents. Steam lances are frequently frequ ently used for cleaning piping assemblies. Steam pressures from 345 to 515 kPa [50 to 75 psi] are usually adequate (see 6.1 6.1). ). 6.2.10 Water-Jetting at water pressures of up to 70 MPa [10 000 psi] is effective for removing grease, oils, chemical accessible weld spatter accessible spatter,, weldin welding g flux, scale, arc strikes strikes,, etc., by grindi gri nding. ng. Accordi According ng to the app applica lication tion,, som somee scal scalee or hea heatt temper may be permissible on the nonprocess side of a weld, but should be removed from the process side if possible. If chemical cleaning of the process side of the weld is deemed necessary, the precautions of this standard shall be observed. Austenitic Austen itic stainle stainless ss steels in the sensitized condition should generally not be descaled with nitric-hydrofluoric acid solutions. Welds may also be cleaned as described in Table A2.1, A2.1, Part III, Treatment Treatment P and Q (also see 5.2.4 and 5.2.5 5.2.5). ). deposits (except adsorbed chemicals), dirt, loose and moderately ate ly ad adhe here rent nt sc scale ale,, an and d ot othe herr co cont ntam amin inan ants ts th that at ar aree no nott actua act ually lly bo bond nded ed to th thee me metal tal.. Th Thee me meth thod od is pa part rtic icul ular arly ly applicable for cleaning piping assemblies which can withstand the high pressures involved; involved; self-p self-propell ropelled ed nozzles or “moles “moles”” are generally used for this purpose. 6.2.11 Acid Cleaning is a process in which a solution of a mineral or organic acid in water, sometimes in combination with wit h a we wetti tting ng ag agen entt or de dete terg rgen entt or bo both th,, is em empl ploy oyed ed to remove rem ove iro iron n and oth other er met metalli allicc con contam taminat ination ion,, ligh lightt oxi oxide de films, shop soil, and similar contaminants. Suggested solutions, contact times, and soluti solution on temperatures temperatures for various alloys are given in Annex A2. A2. Acid cleaning is not generally effective for removal of oils, greases, and waxes. Surfaces shall be precleaned to remove oils and greases before acid cleaning. (See by a ho hott-wa water ter ri rins nsee to re remo move ve re resid sidua uall ch chem emica icals. ls. Sp Spot ot cleaning cleanin g to remov removee localiz localized ed contamination contamination may be accomplished by wiping with a clean, solvent-moistened cloth. If the purchaser specifies passivation, the final cleaning shall be in accordance with the requirements of T Table able A2.1 A2.1,, Part II, or one of the treatments listed in Specification A967/A967M A967/A967M.. Unless specified by the purchaser, the chemical treatment applied to the parts shall be selected by the supplier from among the listed passivation treatments. When the stainless steel parts are to be used use d for app applica lication tionss whe where re cor corros rosion ion res resist istanc ancee is a pri prime me factor fac tor to ach achiev ievee sat satisf isfact actor ory y per perfo forma rmance nce and ser servic vicee requ re quir ireme ement nts, s, or wh where ere pr prod oduct uct co cont ntami aminat nation ion mu must st be avoide avo ided, d, pas passiv sivatio ation n fol follow lowed ed by tho thorou rough gh rin rinsin sing g sev severa erall times with hot water and drying thoroughly after the final water rinse is recommended, whenever practical. A2.10.) Common techniques for acid cleaning are immersion, A2.10. swabbi swa bbing, ng, and spr sprayi aying. ng. Max Maximu imum m sur surfac facee qua quality lity is bes bestt achieved by using a minimum cleaning time at a given acid concentration and temperature. To minimize staining, surfaces 6.5 Precision Cleaning—Certain nuclear, space, and other especially especia lly cri critica ticall app applica licatio tions ns may req requir uiree that onl only y ver very y high-p hig h-puri urity ty alco alcohol hols, s, acet acetone one,, ket ketone ones, s, or oth other er precision used d for final clea cleanin ning g or recl reclean eaning ing of cleaning cleani ng agents be use 6.4 Final Cleaning or Passivation, or Both—If proper care hass be ha been en tak taken en in ear earlie lierr fa fabr brica icatio tion n an and d cle clean anin ing, g, fin final al cleaning may consist of little more than scrubbing with hot water or hot water and detergent (such as trisodium phosphate, TSP), using fiber brushes. Detergent washing shall be followed 5 A380/A380M − 17 critical ical sur surfac faces es aft after er fab fabric ricatio ation n adv advanc ances es to the poi point nt tha thatt crit internal crevices, undrainable spaces, blind holes, or surfaces that are not acce accessi ssible ble for tho thorou rough gh scr scrubb ubbing ing,, rin rinsin sing, g, and inspection are formed. Such items are often assembled under clean-room conditions (see 8.5.5 8.5.5)) and require approval, by the purchaser, of carefully prepared cleaning procedures before the start of fabrication. 6.6.4 When cleaning critical critical installed systems, do not permit the process surfaces to dry between successive cleaning and rinsing steps, or between the final rinse and filling with the layup solution. 7. Inspe Inspectio ction n After Cleaning Cleaning 7.1 General— Ins Inspecti pection on tech techniqu niques es shou should ld repr represen esentt careful, considered review of end use requirements of parts, equi eq uipm pmen ent, t, an and d sy syst stems ems.. Th Ther eree is no su subs bstit titut utee fo forr go good od,, unifor uni form, m, clea cleanin ning g pra practic ctices es whi which ch yie yield ld a meta metallur llurgic gically ally sound and smooth surface, followed by adequ adequate ate prote protection ction to preserve that condition. Establishment of the most reliable tests and test sta standa ndards rds for clea cleanne nness ss are hel helpfu pfull in atta attaini ining ng the desired performance of parts, equipment, and systems. Testing should be sufficiently extensive to ensure the cleanness of all surf su rfac aces es ex expo posed sed to pr proc oces esss flu fluid idss wh when en in se serv rvice ice.. Th Thee follow fol lowing ing rep repres resent ent som somee test testss tha thatt hav havee bee been n suc succes cessfu sfully lly applied to stainless steels. The purchaser shall have the option of spe specif cifyin ying g in his purchase purchase doc docume uments nts that any of thes thesee quality assurance tests be used as the basis for acceptability of the cleanness of the stainless steel item, the absence of iron on the surface, or both. 6.6 Clea Cleaning ning of Ins Install talled ed Sys Systems tems— —Th Ther eree ar aree tw two o ap ap-proaches to cleaning installed systems. In the first, which is probably adequate for most applications, cleaning solutions are circulated through the completed system after erection, taking care to remove or protect items that could be damaged during the cleaning operation. In the second approach, which may be required for gaseous or liquid oxygen, liquid metal, or other reactive-process solutions, piping and components are installed in a manner to avoid or minimize contamination of processsolu so lutio tion n su surf rfac aces es du duri ring ng er erect ectio ion n so th that at lit little tle ad addi ditio tiona nall cleaning is necessary after erection; post-erection flushing, if necessary, is done with the process fluid. If process surfaces are coated with an appreciable amount of iron oxide, a chelating treatmentt or hightreatmen high-pressu pressure re water water-jettin -jetting g treatme treatment nt shou should ld be considered in place of acid treatment (see 6.2.7 aand nd 6.2.10 6.2.10). ). 6.6.1 Post-Erection Cleaning—Circula Circulate te hot water to which a detergent has been added, for at least 4 to 8 h. A water temperature of at least 60 to 70°C [140 to 160°F] is recommended (see 6.1 6.1). ). Rinse by circulating clean hot water until the effluent is clear. If excessive particulate matter is present, the cleaning cycle may be preceded with a high-pressure steam blow, repeating as necessary until a polished-aluminum target on the outlet of the system is no longer dulled and scratched by particulates loosened by the high-velocity steam. Valves and similar items must be protected from damage during a steam blow. 6.6. 6. 6.2 2 If me metal tallic lic ir iron on is de detec tected ted by on onee of th thee me meth thod odss suggested in Section 7 7,, it can be removed by circulating one of the acid passivation solutions solutions sugg suggested ested in 6.4 until laboratory determination for iron, made on samples of the solution taken hourly, indicates no further increase in iron content, after which 7.2.1 Visual—Items cleaned in accordance with this practice should shou ld be fr free ee of pa pain int, t, oi oil, l, gr grea ease se,, we weld ldin ing g flu flux, x, sl slag ag,, heat-tr hea t-treati eating ng and hot hot-fo -formi rming ng sca scale le (ti (tight ghtly ly adh adhere erent nt sca scale le resulting result ing from weldin welding g may be permissible on some surfaces), surfaces), dirt, trash, metal and abrasive particles and chips, and other gross contamination. contamination. Some depo deposited sited atmospheric dust will normal nor mally ly be pre presen sentt on ext exterio eriorr sur surfac faces es but sho should uld not be present on interior surfaces. Visual inspection should be carried out under a lighting level, including both general and supplementary lighting, of at least 1080 lx [100 footcandles], and prefer pre ferabl ably y 270 2700 0 lx [25 [250 0 foo footcan tcandle dles] s] on the sur surfac faces es bei being ng inspec ins pected ted.. Visu isual al ins inspec pectio tion n sho should uld be sup supple plemen mented ted wit with h borescopes, mirrors, and other aids, as necessary, to properly examine inaccessible or difficult-to-see surfaces. Lights should be positioned to prevent glare on the surfaces being inspected. circulation may be stopped and the system drained. After this treatment, circulate clean hot water (that is, without detergent) through the system for 4 h to remove all traces of acid and corrosion product resulting from the acid treatment, or until the pH of the rinse water returns to neutral. 6.6.3 In critical systems where where post-erection post-erection cleaning is not desir de sirab able le (f (for or ex exam ampl ple, e, li liqu quid id ox oxyg ygen en or nu nucl clear ear re react actor or primary coolant systems), on-site erection may be conducted under clean-room conditions. Erection instructions may require that wrapping and seals of incoming materials and equipment be kept intact until the item is inside the clean area, and that careful surveillance be exercised to prevent foreign materials (for example, cleaning swabs or tools) from being dropped or leftt in th lef thee sy syst stem. em. Wh Wher eree co cont ntam amin inati ation on do does es oc occu curr, th thee cleaning procedure usually is developed through consultation 7.2.1.1 Gro Gross ss Indic Indication ationss of Iro Iron— n—When iron contam contaminaination is clearly visible, items should be cleaned in accordance with this practice. 7.2.2 Wipe Tests—Rubbing of a surface with a clean, lintfree, white cotton cloth, commercial paper product, or filter paper moistened (but not saturated) with high-purity solvent (see 6.5 6.5), ), may be used for evaluating the cleanness of surfaces not accessible for direct visual inspection. Wipe tests of small diameter tubing are made by blowing a clean white felt plug, slightly larger in diameter than the inside diameter of the tube, throug thr ough h the tub tubee with clea clean, n, dry dry,, filte filtered red com compre presse ssed d air air.. Cleanness in wipe tests is evaluated by the type of contamination rubbed off on the swab or plug. The presence of a smudge on the cloth is evidence of contamination. In cases of dispute concerning the harmful nature of the contamination, a sample between the erector and the purchaser (or his site representative). Frequently, Frequently, postpost-erectio erection n flushin flushing g is accomp accomplished lished by circulating the process fluid through the system until contamination is reduced to tolerable levels. of the smudg smudgee may be transferred transferred to a clean quart quartzz microscope slide for infrared analysis. The wipe test is sometimes supplemented men ted by rep repeati eating ng the test with a blac black k clot cloth h to dis disclos closee contaminants that would be invisible on a white cloth. 7.2 Gross Inspection: 6 A380/A380M − 17 Residua iduall Patter Pattern— n—Dr Dry y th thee cl clea eane ned d su surf rfac acee af afte terr 7.2.3 Res finish-cleaning at 50°C [120°F] for 20 min. The presence of stain sta inss or wa water ter sp spot otss on th thee dr dried ied su surf rface acess in indi dicat cates es th thee presence of residual soil and incomplete cleaning. The test is rapid but not very sensitive. 7.2.4 W Water-Break ater-Break Test— This is a test for the presence of hydrophobic contaminants on a cleaned surface. It is applicable only for items that can be dipped in water and should be made with high-purity water. The test procedure and interpretation of copper copp er su sulfa lfate te in th thee fo follo llowi wing ng pr prop opor ortio tions ns (Warning— Always add acid to cold water.): Distilled water 95–100 % Sulfuric acid (H2SO4) Copper sulfate pentahydrate (CuSO4·5H2O) 7.3 Precision Inspection: 7.3.1 Solvent-Ring Test is a test to reveal the presence of tightly adherent transparent films that may not be revealed by visual vis ual ins inspec pection tion or wip wipee test tests. s. A com compar pariso ison n stan standar dard d is prepared by placing on a clean quartz microscope slide a single drop of high-purity solvent and allowing it to evaporate. Next place another drop on the surface to be evaluated, stir briefly, and transfer, using a clean capillary or glass rod, to a clean quartz microscope slide and allow the drop to evaporate. Make as many test slides as necessary to give a reasonable sample of thee su th surf rface ace be bein ing g ex exam amin ined ed.. If fo fore reig ign n ma mate teria riall ha hass be been en dissolved by the solvent, a distinct ring will be formed on the outer ou ter edge of th thee dr drop op as it ev evap apor orat ates. es. The na natu ture re of th thee contaminant can be determined by infrared analysis, comparing the infrared analysis with that of the standard. 7.3.2 Bl Black ack Lig Light ht Ins Inspec pectio tion n is a te test st su suit itab able le for th thee detection of certain oil films and other transparent films that are not detectable under white light. In an area that is blacked out to white light, inspect all visible accessible surfaces with the aid of a new new,, floo flood-t d-type ype,, ult ultrav raviol iolet et lamp lamp.. For inac inacces cessib sible le areas, use a wipe test as described in 7.2.2 and subject the used cloth or plug to ultraviolet lamp inspection in a blacked-out area. Fluorescence of the surface, cloth, or plug indicates the presence of contaminants. The nature of the contamination can be determined by subjecting a sample of the contaminant, that has been tra transf nsferr erred ed to a clea clean n qua quartz rtz micr microsc oscope ope slide, to infrared infrar ed analys analysis. is. The test will not detect straig straight-ch ht-chain ain hydrocarbons such as mineral oils. 7.3.3 Atomizer Test is a test for the presence of hydrophobic films. It is applicable to both small and large surfaces that are accessi acce ssible ble for dir direct ect vis visual ual exa examin minatio ation, n, and is abo about ut 100 100× × more sensitive than the water-break test. The test procedure and interpretation of results are described in Test Method F21 F21.. High-purity water should be used for the test. 7.3.4 Ferroxyl Test for Free Iron is a hypersensitive hypersensitive test and should be used only when even traces of free iron or iron oxide might be objectionable. The test can be used on stainless steel to detect iron contamination from sources including, but not limited to, ironiron-tool tool marks, residu residual-iro al-iron n salts from picklin pickling g soluti sol utions ons,, iro iron n dus dust, t, atmo atmosph spheric eric exp exposu osure, re, iro iron n dep deposi osits ts in welds, wel ds, embedded embedded iro iron n and iron oxi oxide. de. The tes testt sol soluti ution on is prepared by first adding nitric acid to distilled water and then adding potassium ferricyanide, in the following proportions: results are described in Test Method F22 F22.. The test is moderately sensiti sensitive. ve. 7.2.5 Tests for Free Iron: 7.2.5.1 Water-Wetting and Drying— Formation of rust stains may be accelerated by periodically wetting the surface with preferably distilled or deionized water or clean, fresh, potable tap water. Application via a hand held sprayer or atomizer that produces small droplets that do not coalesce is optimal. The sampl sam plee sh shou ould ld be re rewe wett as ne need eded ed bu butt all allow owed ed to ai airr dr dry y comp co mple letel tely y at lea least st 8 tim times es,, re remai maini ning ng dr dry y fo forr at lea least st 45 minutes each, and totaling 7 to 9 h in a 24-h test period. After completion comple tion of this test, the surface should show no eviden evidence ce of rust stains or other corrosion products. 7.2.5.2 High-Humidity Test—Su Subj bjec ectt th thee su surf rfac acee to 95 to 100 % humidity at 40 to 45°C [100 to 115°F] in a suitable humidity cabinet for 24 to 26 h. After completion of this test, the surface should show no evidence of rust stains or other corrosion products. 7.2.5.3 Copper Sulfate Test—This highly sensitive method is recommended for the detection of metallic iron or iron oxide on the surface of austenitic 200 and 300 Series, duplex, the precip pre cipitat itation ion har harden dening ing allo alloys, ys, and the fer ferriti riticc 400 Ser Series ies stainless steels containing 16 % chromium or more. It is not recommended for the martensitic and lower chromium ferritic stainless steels of the 400 Series since the test may show a positive reaction on these materials irrespective of the presence or absence of anodi anodicc surfa surface ce contam contaminants inants.. The test solution is prepared by first adding sulfuric acid to distilled water and then dissol dis solvin ving g cop copper per sul sulfat fatee in the fol follow lowing ing pro propor portio tions ns (Warning— Warning—Always Always add acid to cold water.): Distilled water 95–100 % Sulfuric acid (H2SO4) Copper sulfate pentahydrate (CuSO4·5H2O) 90 mL 5.4 mL 4g 250 mL 1 mL 4g Appl Ap ply y th thee tes testt so solu lutio tion n to th thee su surf rfac acee to be in insp spect ected ed,, applying additional solution if needed to keep the surface wet for a period of 6 min. The specimen shall be rinsed and dried in a manner not to remove any deposited copper. A copper deposit indicates the presence of free iron. 7.2.5.4 Martensitic Grade Adherent Copper Sulfate Test— The copper sulfate test as set forth in 7.2.5.3 is not applicable to surgical and dental instruments made of hardened martensitic stainless steels. Instead, Instead, a specia specialized lized copper sulfate test is extensi exte nsivel vely y use used d for the pur purpos posee of det detecti ecting ng fre freee iro iron n and determining overall good manufacturing practice. Copper deposi po sits ts on th thee su surf rfac acee of su such ch in inst stru rume ment ntss ar aree wi wipe ped d wi with th Distilled water Nitric acid (60–67 %) Potassium ferricyanide 94 weight % 3 weight % 3 weight % 1000 mL 20 mL 30 g [1 gal] [0.2 pt] [4 oz] The test solution shall be mixed fresh the day the tests are made since it changes color on standing. Apply solution with an aluminum, plastic, glass, or rubber atomizer having no iron or steel parts, or a swab (atomizer spray is preferred). modera mode rate te vi vigo gorr to de dete term rmin inee if th thee co copp pper er is ad adhe here rent nt or nonadherent. Instruments with nonadherent copper are considered acceptable. The specialized test solution is prepared by first adding sulfuric acid to distilled water and then dissolving 7.3. 7. 3.4. 4.1 1 Th Thee ap appe pear aran ance ce of a bl blue ue st stai ain n wi with thin in 15 s of application is evidence of surface iron contamination. Several minute min utess may be req requir uired ed for detection detection of oxi oxide de scal scale. e. The soluti sol ution on sho should uld be rem remove oved d fro from m the sur surfac facee as qui quickly ckly as 7 A380/A380M − 17 possible after testing using water or, if necessary, white vinegar or a solution of 5 to 20 weight % acetic acid and scrubbing with a fiber brush. Flush the surface with water several times after use of vinegar or acetic acid. sludge in the bottom of cleaning tanks; the formation of oil, scums, scu ms, and und undiss issolv olved ed mat matter ter on liq liquid uid sur surfac faces; es; and hig high h concentrations of emulsified oil, metal or chemical ions, and suspended solids in the liquids. Periodic cleaning of vats and degreasing degre asing tanks tanks,, decanti decanting, ng, period periodic ic bottom bottom-drain -drain,, agitatio agitation n of solutions, and similar provisions are essential to maintain the effectiveness of solutions. Care must be taken to prevent water contamination contamination of trichlo trichloroethy roethylene lene and other halogenated solvents, both while in storage and in use. Redistillation NOTE 3—Potassium ferricyanide is not a dangerous poison as are the simple cyanides. However, when heated to decomposition or in contact with concentrated acid, it emits highly toxic cyanide fumes. NOTE 4—Ru 4—Rubber bber gloves, clothing, clothing, and face shield shieldss shoul should d be worn when applying the test solut solution, ion, and inhala inhalation tion of the atomized spray should shoul d be avoid avoided. ed. NOTE 5—The test is not recommended for process-surfaces of equipment that will be used for processing food, beverages, pharmaceuticals, or other products for human consumption unless all traces of the test solution can be thoro thoroughly ughly removed. and filterin filte ring g of reuse. solven sol vents ts and vap vapor or-de -degre greasin asing g to agents age nts are necessary before Makeup is often required maintain concentrations and pH of cleaning solutions at effective levels. Do not ove overus rusee che chemica micall clea cleaner ners, s, par particu ticular larly ly acid acidss and vapor-degreasing solvents; if light films or oily residues remain on th thee me metal tal su surf rfac aces es af after ter us usee of su such ch ag agen ents, ts, ad addi ditio tiona nall scrubbing with hot water and detergent, followed by repeated rinsing with large quantities of hot water, may be necessary. 8. Pre Precaut cautions ions 8.1 Minimizing Iron Contamination— Iron contamination on stainless steel parts, components, and systems is almost always confi co nfine ned d to th thee su surf rfac ace. e. If re reas ason onab able le ca care re is ta take ken n in fabrication, simple inexpensive cleaning procedures may suffice for its removal, and very little special cleaning should be required. requir ed. Fabrication Fabrication should be confin confined ed to an area where only the one grade of mate material rial is bei being ng wor worked ked.. Pow Powder der cutting cutting should be minimized or prohibited. Handling equipment such as slings, hooks, and lift-truck forks should be protected with 8.3 Rinse Water—Ordinary industrial or potable waters are usually suitable for most metal-cleaning applications. Biologically tested potable water should be used for final rinsing of food-handling, pharmaceutical, dairy, potable-water, and other sanitar san itary y equ equipm ipment ent and sys systems tems.. Rin Rinsin sing g and flus flushin hing g of critica cri ticall com compon ponent entss and sys systems tems aft after er fini finishsh-clea cleanin ning g oft often en requires requi res highhigh-purity purity deionized water, having strict controls on clean wood, cloth, or plastic buffers to reduce contact with the iron surfa surfaces. ces. Walking on corro corrosion-r sion-resistan esistantt alloy surfa surfaces ces should be avoided; where unavoidable, personnel should wear clean shoe covers each time they enter. Kraft paper, blotting paper pap er,, pap paperb erboar oard, d, flan flannel nel,, vin vinylyl-bac backed ked adh adhesi esive ve tape or paper, or other protective material should be laid over areas where personnel are required to walk. Shearing tables, press breaks bre aks,, lay layout out stan stands, ds, and oth other er car carbon bon-st -steel eel wor work k sur surfac faces es should be covered with clean kraft paper, cardboard, or blotting paper to reduce the amount of contact with the carbon steel. Hand Ha nd to tool ols, s, br brus ushe hes, s, mo mold ldin ing g to tool ols, s, an and d ot othe herr to tool olss an and d supplies suppl ies requir required ed for fabrication should be segreg segregated ated from similar items used in the fabrication of carbon steel equipment, and should be restricted to use on the one material; tools and supplies used with other materials should not be brought into halide content, pH, resistivity, turbidity, and nonvolatile residues. Analytical Analytical methods that may be used for establishing establishing the puri pu rity ty of ri rins nsee wa wate terr sh shou ould ld be de demo mons nstr trate ated d to ha have ve th thee sensitivity sensiti vity necessary to detect specified impurity impurity levels; the analy an alytic tical al met metho hods ds gi give ven n in th thee An Annu nual al Bo Book ok of AS ASTM TM Standards, Vol 03.05, are recommended for referee purposes in casee of dis cas disput pute. e. To min minimi imize ze the use of cos costly tly hig high-p h-puri urity ty water, preliminary rinses can often be made with somewhat lesser quality water, followed by final rinsing with the highpurity water. It is also possible in many cases to use effluent or overflow overfl ow from the final rinse operation operation for preliminary preliminary rinsin rinsing g of other items. the fab fabric ricatio ation n area area.. Tool oolss and fixtures fixtures sho should uld be mad madee of hardened tool steel or chrome-plated steel. Wire brushes should be stainless steel, or of an alloy composition similar to the steel being cleaned, and should not have been previously used on other materials. Only new, washed sand that is free of iron particles should be used for casting. high-velocity high-veloci ty,, turbu turbulent lent flow of cleanin cleaning g soluti solutions ons and rinse water may be necessary to provide the scrubbing action needed for effective cleaning and rinsing. The velocity required is a function of the degree of cleanness required and the size of particles that are permissible in the system after the start of operation. For example, if particles between 500 and 1000 µm [0.002 and 0.004 in.] are acceptable to remain, a mean flushing velocity of 0.3 to 0.6 m/s [1 to 2 ft/s] may be sufficient for pipe diameters of DN 50 [NPS 2] and smaller; to remove 100 to 200 µm [0.004 to 0.008 in.] particles, a mean flushing velocity of 0.9 to 1.2 m/s [3 to 4 ft/s] may be required. 8.4 Circulation of Cleaning Solutions and Rinse Water—For restricted internal surfaces (for example, small diameter piping syst sy stem emss or th thee sh shel elll or tu tube be si side de of a he heat at ex exch chan ange ger) r),, 8.2 Reu Reuse se of Clea Cleanin ning g and Pick Pickling ling Sol Soluti utions ons— —Cleaning and pickling agents are weakened and contaminated by materials and soil being removed removed from surfaces as they are cleaned. Solutions Solutio ns may become spent or deplet depleted ed in concen concentratio tration n after extended use, and it is necessary to check concentrations and to replace or replenish solutions when cleaning or pickling action slows. A1.2 and A2.6 give limits for iron content in descaling and passivation solutions respectively. It may be impractical or uneconomical to discard solutions after a single use, even in 8.5 Pr Protectio otection n of Cleaned Surfaces—Measu Measures res to prote protect ct cleaned surfaces should be taken as soon as final cleaning is completed, comple ted, and shoul should d be maintained during all subseq subsequent uent fabrication, fabric ation, shipp shipping, ing, inspec inspection, tion, storag storage, e, and install installation. ation. 8.5.1 8.5 .1 Do not remove remove wra wrappi ppings ngs and seal sealss fro from m inc incomi oming ng materials and components until they are at the use site, ready to be used or installed. If wrappings and seals must be disturbed for receiving inspection, do not damage them, remove no more precision cleanin precision cleaning g operat operations ions (that is, finish finish-cleani -cleaning ng using very high-purity solvents and carried out under clean-room and rigidly controlled environmental conditions). When solutions are re-used, care shall be taken to prevent the accumulation of 8 A380/A380M − 17 than necessar y to car carry ry out the ins inspec pection tion,, and rewrap rewrap and necessary reseal as soon as the inspection is complete. For critical items that were cleaned by the supplier, and that will not be given furt fu rthe herr cle clean anin ing g at th thee us usee sit sitee or af afte terr in inst stall allat atio ion, n, th thee condition of seals and wrappings should be inspected regularly and at fairly short intervals while the item is in storage. 8.5.2 Finish Finish-cleane -cleaned d materia materials ls and components components shou should ld not be stored directly on the ground or floor, and should not be permitt per mitted, ed, ins insofa ofarr as pra practic cticabl able, e, to com comee in con contact tact with 8.5.7 Instal Installed led piping systems systems are often laid up wet, that is, they ar they aree fill filled ed wi with th wa water ter (o (orr pr proc oces esss flu fluid id)) af after ter in in-p -pla lace ce cleanin clea ning g unt until il rea ready dy to be plac placed ed in ser servic vice. e. Sto Storag ragee wat water er should be of the same quality as the makeup water for the system, and should be introduced in a manner that it directly replaces the final flush water without permitting the internal surfaces of the system to dry. 8.5.8 8.5 .8 Equ Equipm ipment ent and asse assembl mblies ies for cri critica ticall app applica licatio tions ns may be sto stored red and shi shippe pped d wit with h pre pressu ssuriz rized, ed, dry dry,, filte filtered red,, asphalt, galvanized or carbon mercury, zinc, lead, low-me low -meltin lting g poi point nt meta metals, ls, orsteel, alloys allo ys or com compou pounds nds ofbrass, such suc h materials. Acid cleaning of surfaces that have been in contact with such materials may be necessary to prevent failure of the item when subsequently heated. The use of carbon or galvanized steel wire for bundling and galvanized steel identification tags should be avoided. 8.5.3 Store materials materials and equip equipment, ment, when in process, on wood wo od sk skid idss or pa palle llets ts or on met metal al su surf rface acess th that at ha have ve be been en protected to prevent direct contact with stainless steel surfaces. Keep openings of hollow items (pipe, tubing, valves, tanks, pumps, pressure vessels, and so forth) capped or sealed at all times except when they must be open to do work on the item, using polyethylene, polyethylene, nylon nylon,, TFE-fl TFE-fluoro uorocarbon carbon plastic, or stainless steel cap caps, s, plu plugs, gs, or seal seals. s. Whe Where re clea cleanne nness ss of ext exteri erior or oil-fr oil-free ee nitrogen prevent preve corrosion they are ready to be installed. Means to shall bent provided foruntil maintaining and monitoring the gas press pressure ure during shipping shipping and storag storage. e. If the item is to be shipped to or through mountains or other areas where the altitude varies greatly from that where it was pressurized, consideration must be given to the effect of that change in altitudee on the pressure inside altitud inside the item, and possible rupture or loss of seals. 8.5.9 8.5 .9 Pre Pressu ssurere-sen sensit sitive ive tap tapee is oft often en use used d for seal sealing ing or protec pro tectiv tivee cov covers ers,, sea seals, ls, cap caps, s, plu plugs, gs, and wra wrapp pping ings. s. If possible, the gummed surface of the tape should not come in contact with stainless steel surfaces. If tape has come in contact with the metal, clean it with solvent or hot water, and vigorous scrubbing. 8.5.10 8.5.1 0 Protec Protective tive adhesive papers papers or plastic plasticss are often used to protect the finish of sheet stock and parts. These materials may ma y ha hard rden en or de deter terio iora rate te wh when en su subj bject ected ed to pr pres essu sure re or sunlight, and damage the surface. These materials may also decompose in time to form substances as described in 8.5.3 8.5.3.. Protect Pro tective ive mat materia eriall sho should uld be rem remove oved d whe when n its fun functio ction n is comple com plete te or its con condit dition ion mon monitor itored ed for dec decomp omposi ositio tion n or deterioration until it is removed. surface surf acess is im impo port rtan ant, t, ke keep ep th thee ite item m wr wrap appe ped d wi with th cl clear ear polyet pol yethyl hylene ene or TFETFE-fluo fluoroc rocarb arbon on pla plastic stic she sheet et at all time timess except exc ept whe when n it is actu actually ally being wor worked ked on. Avoi Avoid d asp asphal halttcontaining materials. Canvas, adhesive paper or plastics such as po poly ly(v (vin inyl yl ch chlo lori ride de)) may de deco comp mpos osee in tim timee to fo form rm corrosive substances, for example, when exposed to sunlight or ultra ul travi viol olet et lig light ht.. Th Thee re reus usee of ca caps ps,, pl plug ugs, s, or pa pack ckag agin ing g material mate rialss sho should uld be avo avoide ided d unl unless ess the they y hav havee bee been n clea cleaned ned prior to reuse. 8.5. 8. 5.4 4 Cle Clean an st stain ainles lesss ste steel el wi wire re br brus ushe hess an and d ha hand nd to tool olss before reuse on corrosion-resistant materials; if they have not been cleaned and if they could have been used on electrolytically different different materials, the surf surfaces aces contacted by the tools should be acid-cleaned. The use of soft-face hammers or terne (lead)-coated, galvanized, or unprotected carbon steel tables, 8.6 Safety—Clea Cleanin ning g ope operat ration ionss oft often en pre presen sentt num numero erous us hazards to both personnel and facilities. [Material] Safety Data Sheets She ets (MS (MSDS/ DS/SDS SDS)) sho should uld be con consul sulted ted to dete determi rmine ne the hazards of handling specific chemicals. 8.6.1 8.6 .1 Precau Precautio tions ns sha shall ll be tak taken en to pro protec tectt per person sonnel nel,, equipment, equip ment, and faciliti facilities. es. This includ includes es prov provisions isions for ventin venting g of explosive or toxic reaction-product gases, safe disposal of used solutions, solutions, prov provision ision of barrie barriers rs and warnin warning g signs signs,, prov provii- jigs, racks, slings, or fixtures should be avoided (see 8.5.2 8.5.2). ). 8.5. 8. 5.5 5 If clo close se co cont ntro roll of pa part rticu iculat latee co conta ntamin minati ation on is required, particularly of internal surfaces, the latter stages of assembly and fabrication may have to be carried out in a clean room. For most large items, an air cleanliness class (see ISO 14644-1 and ISO 14644-2) at the work surface of Class 8 (that is, a maximum of 3 520 000 per m 3 [100 000 per ft 3] particl particles es 0.5 µm [20 µin.] or larger suspended in the air) is probably sufficient. sions for saf sions safee tran transfe sferr of dan danger gerous ous che chemic micals, als, and main maintetenance of constant vigilance for hazards and leaks during the cleaning operation. 8.6.2 8.6 .2 The physica physicall cap capabi ability lity of the item or sys system tem to be cleaned, together with its foundations, to withstand the loads produced by the additional weight of fluids used in the cleaning operati ope ration, on, sha shall ll be est establ ablish ished ed bef before ore the star startt of clea cleanin ning g operations. 8.6.3 Insof Insofar ar as possib possible, le, chemicals having explosive, explosive, toxic, or obnoxious fumes should be handled out of doors. 8.6.4 8.6 .4 The area in whi which ch the cleaning cleaning ope operati ration on is bein being g conducted should be kept clean and free of debris at all times, and should be cleaned upon completion of the operation. NOTE 6—C 6—Clean lean room is a specia specially lly constructed constructed enclos enclosure ure in which intake air is filtered so that the air at a work station contains no more than a specified number of particles of a specified size; special personnel and housekeeping procedures are required to maintain cleanness levels in a clean room (see ISO 14644-1 and ISO 14644-2). 8.7 Disposal of Used Solutions and Water—Federal, state, and local safety and water pollution control regulations should be con consul sulted ted,, par particu ticular larly ly whe when n lar large ge vol volume umess of che chemic mical al soluti sol utions ons mus mustt be dis dispos posed ed of. Con Contro trolled lled rel release ease of lar large ge volumes of rinse water may be necessary to avoid damaging sewers or stream beds. 8.5.6 Workme orkmen n handl handling ing finished cleaned surfaces of critical items should wear clean lint-free cotton, nylon or dacron cloth or polyethylene film gloves. Rubber or plastic gloves are suitabl sui tablee dur during ing pre preclea cleanin ning g ope operat ration ionss or clea cleanin ning g of non non-critical surfa surfaces. ces. 9 A380/A380M − 17 9. Keyw Keywords ords 9.1 austen austenitic itic stainless steels; cleaning; corrosion; corrosion; corrosive service applications; applications; descali descaling; ng; duple duplex x stainle stainless ss steels; ferritic stainless steels; martensitic stainless steels; pickling; stainless steels ANNEXES (Mandatory Information) A1. RECOMMEND RECOMMENDA ATIONS AND PRECAUTIONS FOR ACID DESCALING (PICKLING) OF ST STAINLESS AINLESS STEEL (See Table A1.1. A1.1.) A1.1 Whe A1.1 Where re size and shape shape per permit, mit, immersio immersion n in the acid solution is preferred; when immersion is not practicable, one of the following room-temperature methods may be used: heat treatment or by welding. Crevices resulting from intergranul gra nular ar atta attack ck can col collect lect and con concen centra trate te hal haloge ogens ns und under er service conditions or during cleaning or processing with certain chemicals; these halogens can cause stress-corrosion cracking. These alloys should generally not be acid-pickled while in the sensitized condition. Consideration should be given to stabilized or low-carbon grades if acid pickling after welding is unavoidable. A1.1.1 A1.1. 1 For interior interior surfaces, partially partially fill item with solution and rock, rotate, rotate, or cir circul culate ate so tha thatt all ins inside ide surfaces surfaces are thoroughly wetted. Keep surfaces in contact with acid solution unti un till in insp spec ectio tion n sh show owss th that at sc scale ale is co comp mple letel tely y re remo move ved. d. Additional exposure without agitation may be needed. Treat exterior surfaces in accordance with A1.1.2 A1.1.2.. A1.4 A1 .4 Some Some la lati titu tude de is pe perm rmis issi sibl blee in ad adju just stin ing g ac acid id concentrations, concentration s, tempera temperatures, tures, and contac contactt times. In gener general, al, lower values in this table apply to lower alloys, and higher values to higher alloys. Close control over these variables is nece ne cess ssar ary y on once ce pr prop oper er va valu lues es ar aree es estab tablis lishe hed d in or orde derr to preserve desired finishes or close dimensional tolerances, or both. A1.1.2 Sur A1.1.2 Surfac faces es tha thatt can cannot not be pic pickle kled d by filling the item may be descaled by swabbing or spraying with acid solution forr ab fo abou outt 30 min min,, or un until til in insp spect ectio ion n sh show owss th that at sc scale ale is completely removed. A1.2 Severe pitting pitting may result from prolonged prolonged exposure exposure to certain acid solutions solutions if the solution becomes depleted depleted or if the concentration of metallic salts becomes too high as a result of prolonged prolo nged use of the solutio solution; n; the concen concentration tration of iron shou should ld not exceed 5 weight %; take care to prevent over-pickling. A1.5 Materi Materials als shall be degre degreased ased before acid pickling, pickling, and shall be thoroughly rinsed after completion of pickling; pH of final fin al ri rin nse wa wate terr sh sho oul uld d be be betw twee een n 6 an and d 8 fo forr mo most st applica app licatio tions, ns, or 6.5 to 7.5 for crit critical ical app applica lication tions. s. Whe When n applicable, materials may be vigorously brushed with hot water A1.3 NitricNitric-hydr hydrofluor ofluoric ic acid solutions may inter intergranu granularly larly corrode certain alloys if they have been sensitized by improper TABLE A1.1 Acid Descaling (Pickling) of Stainless Steel AlloyA ConditionB Treatment 200, 300, and 400 Series, duplex, precipitation hardening, harden ing, and maragi maraging ng alloys (except freemachining alloys) fully annealed only A H2SO4, 8–11 %D , Follow by treatment D or F, Annex A2, A2, as appropriate 65–80 [150–180] Time, Minutes 5–45E 200 and 300 Series, 400 Series containing Cr 16 % or more, duplex, and precip precipitatio itation-hard n-hardening ening alloys (except free-machining alloys) fully annealed only B HNO3, 15–25 % plus HF, 1–8 %F,G 20–60 [70–140] 5–30E All free-machining alloys and 400 Series containing less than Cr 16 % fully annealed only C HNO3, 10–15 % plus HF, 0.5–1.5 %F,G 20 (up to 60 with caution) [70–140] 5–30E C Code Co de Solu So luti tion on,, Vol olum ume, e, % A Temperature °C [°F] This table is also applicable to the cast grades equivalent to the families of wrought materials listed. Other heat treatments may be acceptable if proven by experience: see 5.2.1 5.2.1,, A2.4 A2.4,, and A2.5 for further information. C Solution prepared from reagents of following weight %: H 2SO4, 98 %; HNO 3, 67 %; HF, 70 %. D Tight scale may be removed by a dip in this solution for a few minutes followed by water rinse and nitric-hydrofluoric acid treatment as noted. E Minimum contact times necessary to obtain the desired surface should be used in order to prevent over-pickling. Tests should be made to establish correct procedures for specific applications. F For reasons of conven convenience ience and handli handling ng safety, commercial commercial formulations formulations contai containing ning fluoride salts may be found useful in place of HF for preparing nitric-hydroflu nitric-hydrofluoric oric acid solutions. G After pickling and water rinsing, an aqueous caustic permanganate solution containing NaOH, 10 weight % and KMnO 4, 4 weight %, 70 to 80°C [160 to 180°F], 5 to 60 min, may be used as a final dip for removal of smut, followed by thorough water rinsing and drying. B 10 A380/A380M − 17 and a bristle brush or with high-pressure water jet on completion of pickling; an initial low pressure rinse to minimize acid splashing is permissible. To minimize staining, surfaces shall not be permitted to dry between successive steps of the acid descali des caling ng and rin rinsin sing g pro proced cedure ure.. Tho Thorou rough gh dry drying ing sho should uld follow the final water rinse. mended where possible. If acid pickling is unavoidable, parts should be heated at 120 to 150°C [250 to 300°F] for 24 h immediately following acid treatment to drive off the hydrogen and reduce the susceptibility to embrittlement. A1.7 Proper perso personnel nnel protection, protection, includ including ing face shields shields,, rubber rub ber glo gloves ves,, and rub rubber ber pro protec tective tive clo clothi thing, ng, mus mustt be pro pro-vided vid ed whe when n han handli dling ng acid acidss and oth other er cor corros rosive ive che chemica micals. ls. Adequate ventilation and strict personnel-access controls must A1.6 A1. 6 Har Harden denabl ablee 400 Ser Series ies allo alloys, ys, mar maragi aging ng allo alloys, ys, and precipitation-hard precipitation -hardening ening alloys in the harden hardened ed condit condition ion are subject to hydrogen embrittlement or intergranular attack by pickling pick ling acid acids. s. Des Descali caling ng by mech mechani anical cal meth methods ods is rec recomom- be maintained in areas where such chemicals are being used. A2.1.) A2. RECOMMEND RECOMMENDA ATIONS AND PRECAUTIONS FOR ACID CLEANING OF STAINLESS STAINLESS STEEL (See Table A2.1.) A2.1 Trea Treatments tments shown are generally generally adequate for removal of contamination without seriously changing surface appearance of parts. Passivated parts should exhibit a clean surface and should show no etching, pitting, or frosting. The purchaser shall sha ll spe specif cify y whe whethe therr a slig slight ht dis discol colora oration tion is acc accepta eptable ble.. Passivated parts should not exhibit staining attributable to the presence of free iron particles embedded in the surface when subjected to one of the tests described in 7.2.5 or 7.3.4 7.3.4.. For specific requirements for items to be used in corrosive service or wh wher eree su surf rfac acee ap appe pear aran ance ce is cr criti itical cal,, tr trial ialss sh shou ould ld be conducted condu cted to establ establish ish satisfa satisfactory ctory proce procedures dures.. A2.5 NitricNitric-hydro hydrofluori fluoricc acid soluti solutions ons may inter intergranu granularly larly corrode certain alloys if they have been sensitized by improper heat treatment or by welding. Crevices resulting from intergranul gra nular ar atta attack ck can col collect lect and con concen centrat tratee hal haloge ogens ns und under er service conditions or during cleaning or subsequent processing; these halogens can cause stress-corrosion cracking. Such alloys should not be cleaned with nitric-hydrofluoric acid solutions while whi le in the sen sensiti sitized zed con condit dition ion.. Con Consid sidera eration tion sho should uld be given to use of stabilized or low-carbon alloys if this kind of cleaning after welding is unavoidable. A2.6 Sever Severee pitting may resul resultt from prolonged exposure exposure to cert ce rtai ain n ac acid idss if th thee so solu luti tion on be beco come mess de depl plet eted ed or if th thee concentration of metallic salts becomes too high as a result of prolonged prolo nged use of the soluti solution; on; the concen concentration tration of iron shoul should d not exceed 2 weight %; take care to avoid overexposure. A2.2 The hig A2.2 high-c h-carb arbon on and fre free-m e-mach achini ining ng allo alloys ys may be subjectt to etching or discol subjec discoloratio oration n in nitric acid. This tendency can be minimized by the use of high acid concentrations with inhibitors such as Na2Cr2O7·2H2O or CuSO4·5H2O. Oxidizing action increases with increasing concentration of nitric acid; additional oxidizing action is provided by Na 2Cr2O7·2H2 O. Avoid acid cleaning when possible; use mechanical cleaning follow fol lowed ed by scr scrubb ubbing ing with hot wat water er and dete deterg rgent ent,, fina finall thorough water rinsing and drying. A2.7 Nitric acid solutions are effective effective for remov removing ing free iron iro n and oth other er met metalli allicc con contam taminat ination ion,, but are not ef effec fective tive agains aga instt sca scale, le, hea heavy vy dep deposi osits ts of cor corros rosion ion pro produc ducts, ts, tem temper per films, or greasy or oily contaminants. Refer to Annex A1 for recommended practices where scale, heavy deposits of corro- A2.3 Inh A2.3 Inhibi ibitor torss may not alw always ays be req requir uired ed to main maintain tain brig br ight ht fin finis ishe hess on 20 200 0 an and d 30 300 0 Se Seri ries es,, ma mara ragi ging ng,, an and d precipitation-hardening alloys. sion products, or heat-temper discoloration must be Use conventional degreasing methods for removal of removed. greasy or oil contaminants before any acid treatment. A2.4 Harden Hardenable able 400 Series Series,, maragi maraging, ng, and precip precipitation itation-harden har dening ing allo alloys ys in the har harden dened ed con condit dition ion are sub subject ject to hydrogen embrittlement or intergranular attack when exposed to acids that can cause the generation of hydrogen on the item being bein g clea cleaned ned.. Clea Cleanin ning g by mech mechanic anical al meth methods ods or oth other er chemic che mical al met metho hods ds is re reco comme mmend nded ed.. If aci acid d tre treatm atmen entt is unavoidable, parts should be heated at 120 to 150°C [250 to 300°F] for 24 h immediately following acid cleaning to drive off hydrogen and reduce susceptibility to embrittlement. The cleaning methods described in Parts II and III of Table A2.1 will not lead to the generation of hydrogen on hardenable 400 Series, Ser ies, mar maragi aging, ng, and pre precip cipitat itation ion-ha -harde rdenin ning g allo alloys ys in the A2.8 A2. 8 The citr citric ic acid acid-so -sodiu dium m nit nitrate rate treatment treatment is the lea least st hazardous for remov hazardous removal al of free iron and other metallic contaminatio na tion n and lig light ht su surf rface ace con contam tamina inatio tion. n. Sp Spray rayin ing g of the solution, as compared to immersion, tends to reduce cleaning time. hardened condition. Therefore, the post-cleaning thermal treatment is not required when these solutions are used for cleaning. accelerate or improve the overall cleaning action but it may also increase the risk of surface staining or damage. A2.9 A2 .9 Some Some la lati titu tude de is pe perm rmis issi sibl blee in ad adju just stin ing g ac acid id concentrations, temperatures, and contact times; close control over these variables is essential once proper values have been established. Care shall be taken to prevent acid depletion and buildup of metallic salt concentrations with prolonged use of solutions. In general, increasing the treatment temperature may 11 A380/A380M − 17 Cleaning g of Stainl Stainless ess Steel TABLE A2.1 Acid Cleanin Treatment Alloy Condition Code Co de A Solu So luti tion on,, Vol olum ume e% Time, MinutesB Temperature °C [°F] PART I—Cleaning with Nitric-Hydrofluoric Acid Purpose—For use after descaling by mechanical or other chemical methods as a further treatment to remove residual particles of scale or products of chemical action (that is, smut), and to produce a uniform “white pickled” finish. 200 and 300 Series, 400 Series containing Cr 16 % or more, duplex, and precip precipitatio itation-hard n-hardening ening alloys (except free-machining alloys). fully annealed only D HNO3, 6–25 % plus HF, 0.5–8 %C,D 20–60 [70–140] as necessary Free-machining alloys, maraging alloys, and 400 Series containing less than Cr 16 %. fully annealed only E HNO3, 10 % plus HF, 0.5–1.5 %C,D 20 (up to 60 with caution) [70–140] 1–2 PART II—Cleaning-Passivation with Nitric Acid Solution (see also Specification A967/A967M for additional passivation methods) Purpose—For removal of solubl soluble e salts, corrosion corrosion products, and free iron and other metall metallic ic contamination contamination resulting from handli handling, ng, fabrication, fabrication, or exposu exposure re to contam contamiinated atmospheres (see 6.2.11 6.2.11)). 200 and 300 Series, 400 Series, duplex, precipitation hardening and maraging alloys containing Cr 16 % or more (except free-machining alloys). E annealed, cold-rolled, thermally-hardened, or work-hardened, with dull or non-reflective surfaces F HNO3, 20–50 %D 50–70 [120–160] 20–40 [70–100] 10 30 SameE annealed, cold-rolled, thermally hardened, or work-hardened with bright-machined or polished surfaces G HNO3, 20–40 % plus Na2Cr2O7·2H2O, 2–6 weight %D 50–70 [120–160] 20–40 [70–100] 10 30 400 Series, maraging and precipitation-hardening alloys containing less than Cr 16 % high-carbonstraight Cr alloys (except free-machining alloys)E annealed or hardened with dull or non reflective surfaces H HNO3, 20–50 % 45–55 [110–130] 20–40 [70–100] 20 60 SameE annealed or hardened with bright bright machin machined ed or polished surfaces I HNO3, 20–25 % plus Na2Cr2O7·2H2O, 2–6 weight %F 50–55 [120–130] 20–40 [70–100] 15 30 200, 300, and 400 Series free-machining alloys. E annealed or hardened, with bright bright machin machined ed or polished surfaces J HNO3, 20–50 % plus Na2Cr2O7·2H2O, 2–6 weight %F,G 20–50 [70–120] 25 SameE same K HNO3, 1–2 % plus Na2Cr2O7·2H2O, 1–5 weight % 50–60 [120–140] 10H SameE same L HNO3, 12 % plus CuSO4·5H2O, 4 weight %F 50–60 [120–140] 10 Special free-m Special free-machini achining ng 400 Series alloys with more than Mn 1.25 % or more than S 0.40 %E annealed or hardened with bright bright machin machined ed or polished surfaces M HNO3, 40–60 % plus Na2Cr2O7·2H2O, 2–6 weight %F 50–70 [120–160] 20 PART III—Cleaning with Other Chemical Solutions Purpose—General cleaning. 200, 300, and 400 Series (except free-machining alloys), duplex, precipitation hardening and maraging alloys full fu lly y an anne neal aled ed on only ly N citric citr ic ac acid id,, 1 we weig ight ht % pl plus us NaNO3, 1 weight % 20 [70] 60 Same same O ammonium citrate, 5–10 weight % 50–70 [120–160] 10–60 P inhibited solution of hydroxyacetic acid, 2 weight % and formic acid, 1 weight % 95 [200] 6h Assemblies of stainless and carbon steel (for sensitized example, exampl e, heat exchanger with stainl stainless ess steel tubes and carbon steel shell) 12 A380/A380M − 17 TABLE TAB LE A2.1 Continued Same same Q inhibited ammonia neutralized solution of EDTA (ethylene-diamenetetraacetic acid) followed by hot water rinse and dip in solution of 10 ppm ammonium hydroxide plus 100 ppm hydrazine up to 120 [250] 6h A Solution prepared from reagen Solution reagents ts of follow following ing weight %: HNO3, 67 %; HF, 70 %. Minimum, Minimu m, unless range is indica indicated ted C For reasons of convenience and handling safety, commercial formulations containing fluoride salts may be found useful in place of HF for preparing nitrichydrofluoric acid solutions. D After acid cleaning and water rising, a caustic permanganate solution containing NaOH, 10 weight %, and KMnO4, 4 weight %, 70 to 80°C [160 to 180°F], 5 to 60 min, may be used as a final dip for removal of smut, followed by thorough water rinsing and drying. E The purchaser shall have the option of specifying in his purchase documents that all 400 Series ferritic or martensitic parts receive additional treatment as follows: Within 1 h after the water rinse following the specified passivation treatment, all parts shall be immersed in an aqueous solution containing 4 to 6 weight % Na 2Cr2O7 · 2H2O, at 60 to 70°C [140 to 160°F], 30 min. This immersion shall be followed by thorough rinsing with clean water. The parts then shall be thoroughly dried. F See A2.2 A2.2.. G If flash attack (clouding of stainless steel surface) occurs, a fresh (clean) passivating solution or a higher HNO 3 concentration will usually eliminate it. H Shorter times may be acceptable where established by test and agreed upon by the purchaser. B Materials als shall be degreased before before acid treatme treatment, nt, A2.10 Materi and an d sh shall all be th thor orou ough ghly ly ri rins nsed ed af after ter co comp mple letio tion n of ac acid id treatment; pH of final rinse water should be between 6 and 8 for most applications, or 6.5 to 7.5 for critical applications. When applicable, materials may be vigorously brushed with hot water and a bristle brush or with high-pressur high-pressuree water jet on completion of pickling; an initial low pressure rinse to minimize acid spl splash ashing ing is per permis missib sible. le. To min minimiz imizee stai stainin ning, g, surfaces shall not be permitted to dry between successive steps of the aci acid d clea cleanin ning g or pas passiv sivatio ation n and rin rinsin sing g pro proced cedure ure.. Thorough drying should follow the final water rinse. A2.11 Prope A2.11 Properr perso personnel nnel protection, protection, includ including ing face shields shields,, rubber rub ber glo gloves ves,, and rub rubber ber pro protec tective tive clo clothi thing, ng, mus mustt be pro pro-vided vid ed whe when n han handli dling ng acid acidss and oth other er cor corros rosive ive che chemica micals. ls. Adequate Adequ ate ventil ventilation ation and strict personnel personnel access controls must be maintained where such chemicals are being used. A2.12 Picklin Pickling g and cleanin cleaning g or passiv passivating ating solutions solutions containing taini ng ni nitr tric ic ac acid id wi will ll se seve vere rely ly att attack ack car carbo bon n st steel eel ite items ms including the carbon steel in stainless steel-clad assemblies. SUMMARY OF CHANGES Committ Comm ittee ee A0 A01 1 ha hass id iden entifi tified ed th thee lo loca catio tion n of se selec lected ted ch chan ange gess to th this is st stan anda dard rd sin since ce th thee la last st iss issue ue (A380/A380M – 13) that may impact the use of this standard. (Approved Sept. 1, 2017/) (1) Fed. Std 209E replaced by ISO 14644-1 and ISO 14644-2 (5) Removed contents of previous 7.2.5 and placed them in due to its cancellation. (2) 5.2.2 and 6.2.11 precleaning made a requirement in accordance with A1.5 and A2.10. (3) Re Revis vised ed 5.2 5.2.2 .2 and add added ed new 5.2 5.2.3. .3. Ren Renumb umbere ered d sub subsesequent sections accordingly. (4) Revised 6.2.11 and added new 6.2.12. new 7.2.1.1. (6) Revised 7.2.5.1 and 7.2.5.3. (7) Added duplex grades to Tables A1.1 and A2.1. (8) Added low press pressure ure initial rinse option and reduc reduced ed scrubbing requirement in A1.5 and A2.10. (9) Changed time spans to minimums in Table A2.1 Part II. ASTM International International takes no positi position on respecting the validi validity ty of any patent rights assert asserted ed in connec connection tion with any item mentio mentioned ned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the responsible respon sible technical technical committee, which you may attend. If you feel that your comments have not receiv received ed a fair hearing you should make your views known to the ASTM Committee on Standards, at the address shown below. This States. standard is copyrighted by ASTM 100 Barr Drive, PO West PA at 19428-2959, United Individual reprints (singleInternational, or multiple copies) of Harbor this standard mayBox be C700, obtained byConshohocken, contacting ASTM the above address addr ess or at 610610-832832-9585 9585 (pho (phone), ne), 610610-832832-9555 9555 (fax (fax), ), or serv service@ ice@astm astm.org .org (e-m (e-mail) ail);; or thro through ugh the ASTM webs website ite (www.astm. (www .astm.org). org). 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