ASTM_A_380-A380M-17.pdf

This international standard was developed in accordance with internationallygnized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.Designation:A380/A380M-17NTERNATIONALStandard Practice forCleaning,Descaling,and Passivation of Stainless SteelParts,Equipment,and Systems1This standard is issued under the fixed designation A380/A380M:the number immediately following the designation indicates the yearof original adoption or.in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.A superscript epsilon(e)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.Scope1.1.1.2 Passivation is removal of exogenous iron or iron1.I This practice covers recommendations and precautionscompounds from the surface of a stainless steel by means of afor cleaning,descaling,and passivating of new stainless steelchemical dissolution,most typically by a treatment with anparts,assemblies,equipment,and installed systems.Theseacid solution that will remove the surface contamination butrecommendations are presented as procedures for guidancewill not significantly affect the stainless steel itself.Thiswhen it is recognized that for a particular service it is desiredprocess is described in a general way in 6.2.1I and definedto remove surface contaminants that may impair the normalprecisely in 6.4 with further reference to the requirements ofcorrosion resistance,or result in the later contamination of theAnnex A2 and Part II of the table on acid cleaning of steel.particular stainless steel grade,or cause product contamination.Unless otherwise specified,it is this definition of passivationThe selection of procedures from this practice to be applied tothat is taken as the meaning of a specified requirement forthe parts may be specified upon agreement between thepassivation.(See also Specification A967/A967M.)supplier and the purchaser.For certain exceptional1.1.1.3 Passivation is the chemical treatment of a stainlessapplications,additional requirements which are not covered bysteel with a mild oxidant,such as a nitric acid solution,for thethis practice may be specified upon agreement between thepurpose of enhancing the spontaneous formation of the protec-supplier and the purchaser.Although they apply primarily totive passive metal oxide film.Such chemical treatment ismaterials in the composition ranges of the austenitic,ferritic,generally not necessary for the formation of the passive metalmartensitic,and duplex stainless steels,the practices describedoxide film.may also be useful for cleaning other metals if due consider-1.1.1.4 Passivation does not indicate the separate process ofation is given to corrosion and possible metallurgical effects.descaling as described in Section 5,although descaling may be1.1.1 The term passivation is commonly applied to severalnecessary before passivation can be effective.Depending ondistinctly different operations or processes relating to stainlessthe application,chemical descaling(acid pickling)as describedsteels.In order to avoid ambiguity in the setting ofin 5.2.1 may provide sufficient passivation as defined inrequirements,it may be necessary for the purchaser to define1.1.1.2.precisely the intended meaning of passivation.Some of the1.2 This practice does not cover decontamination or clean-various meanings associated with the term passivation that areing of equipment or systems that have been in service,nor doesin common usage include the following:it cover descaling and cleaning of materials at the mill.On the1.1.1.I Passivation is the process by which a stainless steelother hand,some of the practices may be applicable for thesewill spontaneously form a chemically resistant surface whenpurposes.While the practice provides recommendations andexposed to air or other oxygen-containing environments.It wasinformation concerning the use of acids and other cleaning andat one time considered that an oxidizing treatment was neces-descaling agents,it cannot encompass detailed cleaning proce-sary to establish this passive metal oxide film,but it is nowdures for specific types of equipment or installations.Itaccepted that this film will form spontaneously in an oxygen-therefore in no way precludes the necessity for careful planningcontaining environment providing that the surface has beenand judgment in the selection and implementation of suchthoroughly cleaned or descaled.procedures.1.3 These practices may be applied when free iron,oxidescale,rust,grease,oil,carbonaceous or other residual chemicalThis practice is under the jurisdiction of ASTM Committee A0l on Steel,films,soil,particles,metal chips,dirt,or other nonvolatileStainless Steel and Related Alloys and is the direct responsibility of Subcommittcedeposits might adversely affect the metallurgical or sanitaryA01.14 on Methods of Corrosion Testing.Current edition approved Sept.1.2017.Published September 2017.Originallycondition or stability of a surface,the mechanical operation ofapproved in 1954.Last previous edition approved in 2013 as A380/A380M-13.a part,component,or system,or contaminate a process fluid.D01:10.1520/A0380A0380M-17.The degree of cleanness required on a surface depends on the*A Summary of Changes section appears at the end of this standardCopyright ASTM Intemational,100 Barr Harbor Drive,PO Box C700.West Conshohocken,PA 19428-2959.United StatesMeRe5ae.100920170的2858MDTA380/A380M-17application.In some cases,no more than degreasing or removalF22 Test Method for Hydrophobic Surface Films by theof gross contamination is necessary.Others,such as food-Water-Break Testhandling,pharmaceutical,aerospace,and certain nuclear2.2 ISO Standards:3applications,may require extremely high levels of cleanness,ISO 14644-1 Cleanrooms and associated controlled environ-including removal of all detectable residual chemical films andments-Part 1:Classification of air cleanliness by particlecontaminants that are invisible to ordinary inspection methods.concentrationNore 1-The term iron.when hereinafter referred to as a surfaceISO 14644-2 Cleanrooms and associated controlled environ-contaminant,shall denote free iron.ments-Part 2:Monitoring to provide evidence of1.4 Attainment of surfaces that are free of iron,metalliccleanroom performance related to air cleanliness by par-ticle concentrationdeposits,and other contamination depends on a combination ofproper design,fabrication methods,cleaning and descaling.3.Designand protection to prevent recontamination of cleaned surfaces.Meaningful tests to establish the degree of cleanness of a3.1 Consideration should be given in the design of parts.surface are few,and those are often difficult to administer andequipment,and systems that will require cleaning to minimizeto evaluate objectively.Visual inspection is suitable for thethe presence of crevices,pockets,blind holes,undrainabledetection of gross contamination,scale,rust,and particulates.cavities,and other areas in which dirt,cleaning solutions,orbut may not reveal the presence of thin films of oil or residualsludge might lodge or become trapped,and to provide forchemical films.In addition,visual inspection of internaleffective circulation and removal of cleaning solutions.Insurfaces is often impossible because of the configuration of theequipment and systems that will be cleaned in place or thatitem.Methods are described for the detection of free iron andcannot be immersed in the cleaning solution,it is advisable totransparent chemical and oily deposits.slope lines for drainage:to provide vents at high points anddrains at low points of the item or system;to arrange for1.5 This practice provides definitions and describes prac-removal or isolation of parts that might be damaged by thetices for cleaning.descaling.and passivation of stainless steelcleaning solution or fumes from the cleaning solutions;toparts.Tests with acceptance criteria to demonstrate that theprovide means for attaching temporary fill and circulationpassivation procedures have been successful are listed in 7.2.5lines;and to provide for inspection of cleaned surfaces.and 7.3.4,and can also be found in Specification A967/A967M.3.2 In a complex piping system it may be difficult todetermine how effective a cleaning operation has been.One1.6 The values stated in either SI units or inch-pound unitsmethod of designing inspectability into the system is to provideare to be regarded separately as standard.The values stated ina short flanged length of pipe(that is,a spool piece)at aeach system may not be exact equivalents;therefore,eachlocation where the cleaning is likely to be least effective;thesystem shall be used independently of the other.Combiningspool piece can then be removed for inspection upon complevalues from the two systems may result in non-conformancetion of cleaning.with the standard.1.7 This standard does not purport to address all of the4.Precleaningsafery concerns,if any,associated with its use.It is the4.1 Precleaning is the removal of grease,oil,paint,soil,grit,responsibility of the user of this standard to establish appro-and other gross contamination preparatory to a fabricationpriate safery and health practices and determine the applica-process or final cleaning.Precleaning is not as critical and isbility of regulatory limitations prior to use.(For more specificgenerally not as thorough as subsequent cleaning operations.safety precautions see 7.2.5.3,7.3.4,Section 8,Al.7,andMaterials are usually precleaned before hot-forming,A2.11.)annealing,or other high-temperature operation,before any1.8 This international standard was developed in accor-descaling operation,and before any finish-cleaning operationdance with internationally recognized principles on standard-where the parts will be immersed or where the cleaningization established in the Decision on Principles for thesolutions will be reused.Items that are subject to severalDevelopment of International Standards,Guides and Recom-redraws or a series of hot-forming operations,with intermedi-mendations issued by the World Trade Organization Technicalate anneals,shall be cleaned after each forming operation,priorBarriers to Trade(TBT)Committee.to annealing.Precleaning may be accomplished by vapor2.Referenced Documentsdegreasing:immersion in,spraying,or swabbing with alkalineor emulsion cleaners:steam;or high-pressure water-jet(see2.1 ASTM Standards:26.2)A967/A967M Specification for Chemical Passivation Treat-ments for Stainless Steel Parts5.DescalingF21 Test Method for Hydrophobic Surface Films by the5.1 General-Descaling is the removal of heavy,tightlyAtomizer Testadherent oxide films resulting from hot-forming,heat-treatment,welding.and other high-temperature operations2 For referenced ASTM standards,visit the ASTM website,www.astm.org.orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information.refer to the standards Document Summary page on3 Available from International Organization for Standardization.ISO Centralthe ASTM website.Secretariat.Chemin de Blandonnet 8.CP 401.1214 Vernier.Geneva,Switzerland.2with ASTMcense from HS4 ot for Ressle.100925170285gDA380/A380M-17Because mill products are usually supplied in the descaledtions(such as the presence of crevices).If used,neutralizationcondition,descaling(except removal of localized scale result-is usually also followed by rinsing with clean water to removeing from welding)is generally not necessary during fabricationall traces of the neutralizing agent and thorough drying.Toof equipment or erection of systems(see 6.3).When necessary,minimize staining.surfaces shall not be permitted to dryscale may be removed by one of the chemical methods listedbetween successive steps of the acid descaling and rinsingbelow,by mechanical methods(for example,abrasive blasting.procedure(see Al.5).sanding,grinding,power brushing).or by a combination of5.2.6 Chemical descaling methods,factors in their selection,these.and precautions in their use are described in the Metals5.2 Chemical Descaling(Pickling)-Chemical descalingHandbook.When chemical descaling is necessary,it shouldagents include aqueous solutions of sulfuric acid,or nitric andbe done while the part is in its simplest possible geometry,hydrofuoric acids,as described in Annex Al.Table Al.I.before subsequent fabrication or installation steps create inter-molten alkali or salt baths,and various proprietary formula-nal crevices or undrainable spaces that may trap descalingtions.The safety precautions of 8.6 shall be observed in the useagents,sludge,particles,or contaminated rinse water thatof these methods.Particular care shall be exercised whenmight either result in eventual corrosion or adversely affectpickling closed systems and items with crevices or internaloperation of the item after it is placed in service.voids to prevent retention of pickling solutions and residues.5.3 Mechanical Descaling-Mechanical descaling methods5.2.I Acid Pickling-Nitric-hydrofluoric acid solution isinclude abrasive blasting,power brushing,sanding,grinding,most widely used by fabricators of stainless steel equipmentand chipping.Procedural requirements and precautions forand removes both metallic contamination,and welding andsome of these methods are given in the Metals Handbook.heat-treating scales.Its use should be carefully controlled andMechanical descaling methods have the advantage that they dois not recommended for descaling sensitized austenitic stain-not produce such physical or chemical conditions as inter-less steels or hardened martensitic stainless steels or where itgranular attack,pitting.hydrogen embrittlement,cracks,orcan come into contact with carbon steel parts,assemblies,smut deposits.For some materials,in particular the austeniticequipment,and systems.See also A1.3.Solutions of nitric acidstainless steels when in the sensitized condition and thealone are usually not effective for removing heavy oxide scale.martensitic stainless steels when in the hardened condition,5.2.2 Surfaces to be descaled shall be precleaned to removemechanical descaling may be the only suitable method.Grind-oils and greases prior to acid treatment(see Al.5),and areing is usually the most effective means of removing localizedusually precleaned prior to other chemical treatments.scale such as that which results from welding.Disadvantages5.2.3 When size and shape of product permit,total immer-of mechanical descaling are cost,as compared to chemicalsion in the pickling solution is preferred.Where immersion isdescaling,and the fact that surface defects(for example,laps,impractical,descaling may be accomplished by(/wetting thepits,slivers)may be obscured,making them difficult to detect.surfaces by swabbing or spraying,or(2)by partially filling the5.3.1 Surfaces to be descaled may have to be precleaned.item with pickling solution and rotating or rocking to slosh theParticular care must be taken to avoid damage by mechanicalsolution so that all surfaces receive the required chemicalmethods when descaling thin sections,polished surfaces,andtreatment.The surface should be kept in contact with agitatedclose-tolerance parts.After mechanical descaling,surfacessolution for about 15 to 30 min or until inspection shows thatshould be cleaned by scrubbing with hot water and fibercomplete scale removal has been accomplished.Withoutbrushes,followed by rinsing with clean,hot water.agitation,additional exposure time may be required.If rocking5.3.2 Grinding wheels and sanding materials should notor rotation are impracticable,pickling solution may be circu-contain iron,iron oxide,zinc,or other undesirable materialslated through the item or system until inspection shows thatthat may cause contamination of the metal surface.Grindingdescaling has been accomplished.wheels,sanding materials,and wire brushes previously used on5.2.4 Over-pickling must be avoided.Uniform removal ofother metals should not be used on stainless steel.Wire brushesscale with acid pickling depends on the acid used,acidshould be of a stainless steel which is equal in corrosionconcentration,solution temperature,and contact time(seeresistance to the material being worked on.Annex Al).Continuous exposure to pickling solutions for5.3.3 Clean,previously unused abrasives,such as glassmore than 30 min is not recommended.The item should bebeads or iron-free silica or alumina sand,are recommended fordrained and rinsed after 30 min and examined to check theabrasive blasting.Steel shot or grit is generally not recom-effectiveness of the treatment.Additional treatment may bemended because of the possibility of embedding iron particles.required.Most pickling solutions will loosen weld and heat-The use of stainless steel shot or grit reduces the danger oftreating scale but may not remove them completely.Intermit-rusting and iron contamination,but cannot completely elimi-tent scrubbing with a stainless steel brush or fiber-bristle brush.nate the possibility of embedding residues of iron-oxide scale.in conjunction with pickling or the initial rinse,may facilitate5.3.4 If a totally iron and scale free surface is required,mostthe removal of scale particles and products of chemicalabrasive blasting may be followed by a brief acid dip(seereaction(that is,pickling smut).Annex A2)or passivation treatment(see 6.4).5.2.5 After chemical descaling,surfaces shall be thoroughlyrinsed with clean water to remove all traces of residualchemicals and thoroughly dried after the final water rinse.A4Surface Cleaning.Finishing.and Coating.Metals Handbook,Am.Soc.neutralization treatment may be necessary under some condi-Metals.9th ed.Vol 5.1982.with ASThcense from IHSNot for Resale.1009201700:28:58 MDTA380/A380M-176.Cleaning6.2.2 Emulsion Cleaning is a process for removing oily6.1 General-Cleaning includes all operations necessary fordeposits and other common contaminants from metals by thethe removal of surface contaminants from metals to ensure(/use of common organic solvents dispersed in an aqueousmaximum corrosion resistance of the metal,(2)prevention ofsolution with the aid of a soap or other emulsifying agent(anproduct contamination,and(3)achievement of desired appear-emulsifying agent is one which increases the stability of aance.Cleanness is a perishable condition.Careful planning isdispersion of one liquid in another).It is effective for removingnecessary to achieve and maintain clean surfaces,especiallya wide variety of contaminants including pigmented andwhere a high degree of cleanness is required.Selection ofunpigmented drawing compounds and lubricants,cuttingcleaning processes is influenced mainly by the type of con-fluids,and residues resulting from liquid penetrant inspection.taminant to be removed,the required degree of cleanness,andEmulsion cleaning is used when rapid,superficial cleaning iscost.If careful control of fabrication processes,sequencing ofrequired and when a light residual film of oil is not objection-cleaning and fabrication operations,and measures to preventable.recontamination of cleaned surfaces are exercised,very little6.2.3 Solvent Cleaning is a process for removing contami-special cleaning of the finished item or system may benants from metal surfaces by immersion or by spraying ornecessary to attain the desired level of cleanness.If there is aswabbing with common organic solvents such as the aliphaticquestion concerning the effectiveness of cleaning agents orpetroleums,chlorinated hydrocarbons,or blends of these twoprocedures,or the possible adverse effects of some cleaningclasses of solvents.Cleaning is usually performed at or slightlyagents or procedures on the materials to be cleaned,trial runsabove room temperature.Except for parts with extremelyusing test specimens and sensitive inspection techniques mayheavy contamination or with hard-to-reach areas,or both,goodbe desirable.Descriptions,processes,and precautions to beagitation will usually eliminate the need for prolonged soaking.observed in cleaning are given in the Metals Handbook.Virtually all metal can be cleaned with the commonly usedProprietary cleaners may contain harmful ingredients,such assolvents unless the solvent has become contaminated with acid.chlorides or sulfur compounds,which could adversely affectalkali,oil,or other foreign material.Chlorinated solvents arethe performance of a part,equipment,or system under servicenot recommended for degreasing of closed systems or itemsconditions.It is recommended that the manufacturer of thewith crevices or internal voids.cleaner be consulted if there is reason for concern.6.2.4 Vapor Degreasing is a generic term applied to aNorE 2-Instances are known where stainless steel vessels have stresscleaning process that employs hot vapors of a volatile chlori-cracked before start-up due to steaming out or boiling out with anated solvent to remove contaminants,and is particularlychloride-containing detergent.effective against oils,waxes,and greases.The cleanness and6.2 Cleaning Methods-Degreasing and general cleaningchemical stability of the degreasing solvent are critical factorsmay be accomplished by immersion in,swabbing with,orin the efficiency of the vapor and possible chemical attack ofspraying with alkaline,emulsion,solvent,detergent,chelate,orthe metal.Water in the degreasing tank or on the item beingacid cleaners or a combination of these;by vapor degreasing:cleaned may react with the solvent to form hydrochloric acid.by ultrasonics using various cleaners:by various mechanicalwhich is usually harmful to the metal.No water should bemethods:by steam,with or without a cleaner:or by high-present in the degreasing tank or on the item being cleanedpressure water-jetting.The cleaning method available at anyAcids,oxidizing agents,and cyanides must be prevented fromgiven time during the fabrication or installation of a componentcontaminating the solvent.Materials such as silicones causeor system is a function of the geometric complexity of the item.foaming at the liquid-vapor interface and may result inthe type of contamination present,the degree of cleanlinessrecontamination of the workpiece as it is removed from therequired,and cost.Methods commonly used for removingdegreaser.Vapor degreasing with chlorinated solvents is notdeposited contaminants(as opposed to scale)are describedrecommended for closed systems or items with internal voidsbriefly below and in greater detail(including factors to beor crevices.considered in their selection and use)in the Metals Handbookand the SSPC Steel Structures Painting Handbook.The safety6.2.5 Ultrasonic Cleaning is often used in conjunction withprecautions of 8.6 shall be observed in the use of thesecertain solvent and detergent cleaners to loosen and removemethods.Particular care shall be exercised when cleaningcontaminants from deep recesses and other difficult to reachclosed systems and items with crevices or internal voids toareas,particularly in small work-pieces.Cavitation in theprevent retention of cleaning solutions and residues.liquid produced by the high frequency sound causes micro6.2.1 Alkaline Cleaning is used for the removal of oily,agitation of the cleaner in even tiny recesses of the workpiece,semisolid,and solid contaminants from metals.To a greatmaking the method especially desirable for cleaning parts orextent the solutions used depend on their detergent qualities forassemblies having an intricate configuration.For extremelycleaning action and effectiveness.Agitation and temperature ofhigh levels of surface cleanness,high-purity solvents(1 ppmthe solution are important.total nonvolatile residue)are required.6.2.6 Synthetic Detergents are extensively used as surface-active agents because they are freer rinsing than soaps,aid insoils dispersion,and prevent recontamination.They are effec-5 Good Painting Practices,Stcel Structures Painting Council.Vol 1.1982.Chapters2.0-2.9.3.1-3.2.tive for softening hard water and in lowering the surface andinterfacial tensions of the solutions.Synthetic detergents,inwith ASThmitted without license from IHS4cMfa月ee.10092017002858UDA380/A380M-17particular,should be checked for the presence of harmfulshall not be permitted to dry between successive steps of theingredients as noted in 6.1.acid cleaning and rinsing procedure.Acid cleaning is not6.2.7 Chelate Cleaning-Chelates are chemicals that formrecommended where mechanical cleaning or other chemicalsoluble,complex molecules with certain metal ions,inactivat-methods will suffice on the basis of intended use and,as maying the ions in solution so they cannot normally react withbe necessary,on inspection tests(see 7.2 and 7.3).Require-another element or ions to produce precipitates or scale.Theyments for superfluous cleaning and inspection testing can resultenhance the solubility of scales and certain other contaminants.in excessive costs.Acid cleaning,if not carefully controlled,do not precipitate different scales when the cleaning solutionmay damage the surface and may result in further contamina-becomes spent,and can be used on some scales and contami-tion of the surface.nants that even mineral acids will not attack.When properly6.2.12 Rinsing-After cleaning with an aqueous chemicalused(chelating agents must be continuously circulated andcleaning solution,surfaces shall be thoroughly rinsed withmust be maintained within carefully controlled temperatureclean water to remove all traces of residual chemicals andlimits),intergranular attack,pitting,and other harmful effectsthoroughly dried after the final water rinse.A neutralizationare minimal.Chelating agents are particularly useful fortreatment may be necessary under some conditions(such as thecleaning installed equipment and systems.presence of crevices).If used,neutralization is usually also6.2.8 Mechanical Cleaning(also see 5.3)-Abrasivefollowed by rinsing with clean water to remove all traces of theblasting,vapor blasting using a fine abrasive suspended inneutralizing agent and thorough drying.(See A2.10.)water,grinding,or wire brushing are often desirable for6.3 Cleaning of Welds and Weld-Joint Areas-The joint arearemoving surface contaminants and rust.Cleanliness of abra-and surrounding metal for several inches back from the jointsives and cleaning equipment is extremely important to preventpreparation,on both faces of the weld,should be cleanedrecontamination of the surfaces being cleaned.Although sur-immediately before starting to weld.Cleaning may be accom-faces may appear visually clean following such procedures,plished by brushing with a clean stainless steel brush orresidual films which could prevent the formation of an opti-scrubbing with a clean,lint-free cloth moistened with solvent,mum passive condition may still be present.Subsequentor both.When the joint has cooled after welding,remove alltreatment such as additional iron-free abrasive cleaningaccessible weld spatter,welding flux,scale,arc strikes,etc.,bymethods,acid cleaning,passivation,or combinations of thesegrinding.According to the application,some scale or heatis,therefore,required for stainless steel parts,equipment,andtemper may be permissible on the nonprocess side of a weld,systems to be used where corrosion resistance is a prime factorbut should be removed from the process side if possible.Ifto satisfy performance and service requirements,or wherechemical cleaning of the process side of the weld is deemedproduct contamination must be avoided.necessary,the precautions of this standard shall be observed.6.2.9 Steam Cleaning is used mostly for cleaning bulkyAustenitic stainless steels in the sensitized condition shouldobjects that are too large for soak tanks or spray-washinggenerally not be descaled with nitric-hydrofluoric acid solu-equipment.It may be used with cleaning agents such astions.Welds may also be cleaned as described in Table A2.1,emulsions,solvents,alkalis,and detergents.Steam lances arePart III,Treatment P and O(also see 5.2.4 and 5.2.5).frequently used for cleaning piping assemblies.Steam pres-6.4 Final Cleaning or Passivation,or Both-If proper caresures from 345 to 515 kPa 50 to 75 psiare usually adequatehas been taken in earlier fabrication and cleaning.final(see6.1).cleaning may consist of little more than scrubbing with hot6.2.10 Water-Jetting at water pressures of up to 70 MPawater or hot water and detergent(such as trisodium phosphate10 000 psil is effective for removing grease,oils,chemicalTSP),using fiber brushes.Detergent washing shall be followeddeposits(except adsorbed chemicals).dirt,loose and moder-by a hot-water rinse to remove residual chemicals.Spotately adherent scale,and other contaminants that are notcleaning to remove localized contamination may be accom-actually bonded to the metal.The method is particularlyplished by wiping with a clean,solvent-moistened cloth.If theapplicable for cleaning piping assemblies which can withstandpurchaser specifies passivation,the final cleaning shall be inthe high pressures involved:self-propelled nozzles or molesaccordance with the requirements of Table A2.1,Part II,or oneare generally used for this purpose.of the treatments listed in Specification A967/A967M.Unless6.2.11 Acid Cleaning is a process in which a solution of aspecified by the purchaser,the chemical treatment applied tomineral or organic acid in water,sometimes in combinationthe parts shall be selected by the supplier from among the listedwith a wetting agent or detergent or both,is employed topassivation treatments.When the stainless steel parts are to beremove iron and other metallic contamination,light oxideused for applications where corrosion resistance is a primefilms,shop soil,and similar contaminants.Suggested solutions.factor to achieve satisfactory performance and servicecontact times,and solution temperatures for various alloys arerequirements,or where product contamination must begiven in Annex A2.Acid cleaning is not generally effective foravoided.passivation followed by thorough rinsing severalremoval of oils,greases,and waxes.Surfaces shall be pre-times with hot water and drying thoroughly after the final watercleaned to remove oils and greases before acid cleaning.(Seerinse is recommended,whenever practical.A2.10.)Common techniques for acid cleaning are immersion,6.5 Precision Cleaning-Certain nuclear,space,and otherswabbing,and spraying.Maximum surface quality is bestespecially critical applications may require that only veryachieved by using a minimum cleaning time at a given acidhigh-purity alcohols.acetone,ketones,or other precisionconcentration and temperature.To minimize staining,surfacescleaning agents be used for final cleaning or recleaning of5nse from HSNot for Resale.1009201700:28:58 MDT