1、Designation: A380/A380M 17Standard 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
2、of revision, the year of last revision. A number in parentheses indicates the year of last 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. Scope*1.1 This p
3、ractice covers recommendations and precautionsfor cleaning, descaling, and passivating of new stainless steelparts, assemblies, equipment, and installed systems. Theserecommendations are presented as procedures for guidancewhen it is recognized that for a particular service it is desiredto remove su
4、rface contaminants that may impair the normalcorrosion resistance, or result in the later contamination of theparticular stainless steel grade, or cause product contamination.The selection of procedures from this practice to be applied tothe parts may be specified upon agreement between thesupplier
5、and the purchaser. For certain exceptionalapplications, additional requirements which are not covered bythis practice may be specified upon agreement between thesupplier and the purchaser. Although they apply primarily tomaterials in the composition ranges of the austenitic, ferritic,martensitic, an
6、d duplex stainless steels, the practices describedmay also be useful for cleaning other metals if due consider-ation is given to corrosion and possible metallurgical effects.1.1.1 The term passivation is commonly applied to severaldistinctly different operations or processes relating to stainlessste
7、els. In order to avoid ambiguity in the setting ofrequirements, it may be necessary for the purchaser to defineprecisely the intended meaning of passivation. Some of thevarious meanings associated with the term passivation that arein common usage include the following:1.1.1.1 Passivation is the proc
8、ess by which a stainless steelwill spontaneously form a chemically resistant surface whenexposed to air or other oxygen-containing environments. It wasat one time considered that an oxidizing treatment was neces-sary to establish this passive metal oxide film, but it is nowaccepted that this film wi
9、ll form spontaneously in an oxygen-containing environment providing that the surface has beenthoroughly cleaned or descaled.1.1.1.2 Passivation is removal of exogenous iron or ironcompounds from the surface of a stainless steel by means of achemical dissolution, most typically by a treatment with an
10、acid solution that will remove the surface contamination butwill not significantly affect the stainless steel itself. Thisprocess is described in a general way in 6.2.11 and definedprecisely in 6.4 with further reference to the requirements ofAnnex A2 and Part II of the table on acid cleaning of ste
11、el.Unless otherwise specified, it is this definition of passivationthat is taken as the meaning of a specified requirement forpassivation. (See also Specification A967/A967M.)1.1.1.3 Passivation is the chemical treatment of a stainlesssteel with a mild oxidant, such as a nitric acid solution, for th
12、epurpose of enhancing the spontaneous formation of the protec-tive passive metal oxide film. Such chemical treatment isgenerally not necessary for the formation of the passive metaloxide film.1.1.1.4 Passivation does not indicate the separate process ofdescaling as described in Section 5, although d
13、escaling may benecessary before passivation can be effective. Depending onthe application, chemical descaling (acid pickling) as describedin 5.2.1 may provide sufficient passivation as defined in1.1.1.2.1.2 This practice does not cover decontamination or clean-ing of equipment or systems that have b
14、een in service, nor doesit cover descaling and cleaning of materials at the mill. On theother hand, some of the practices may be applicable for thesepurposes. While the practice provides recommendations andinformation concerning the use of acids and other cleaning anddescaling agents, it cannot enco
15、mpass detailed cleaning proce-dures for specific types of equipment or installations. Ittherefore in no way precludes the necessity for careful planningand judgment in the selection and implementation of suchprocedures.1.3 These practices may be applied when free iron, oxidescale, rust, grease, oil,
16、 carbonaceous or other residual chemicalfilms, soil, particles, metal chips, dirt, or other nonvolatiledeposits might adversely affect the metallurgical or sanitarycondition or stability of a surface, the mechanical operation ofa part, component, or system, or contaminate a process fluid.The degree
17、of cleanness required on a surface depends on the1This practice is under the jurisdiction of ASTM Committee A01 on Steel,Stainless Steel and Related Alloys and is the direct responsibility of SubcommitteeA01.14 on Methods of Corrosion Testing.Current edition approved Sept. 1, 2017. Published Septemb
18、er 2017. Originallyapproved in 1954. Last previous edition approved in 2013 as A380/A380M 13.DOI: 10.1520/A0380_A0380M-17.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
19、This international standard was developed in accordance with internationally recognized 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
20、 (TBT) Committee.1application. In some cases, no more than degreasing or removalof gross contamination is necessary. Others, such as food-handling, pharmaceutical, aerospace, and certain nuclearapplications, may require extremely high levels of cleanness,including removal of all detectable residual
21、chemical films andcontaminants that are invisible to ordinary inspection methods.NOTE 1The term “iron,” when hereinafter referred to as a surfacecontaminant, shall denote free iron.1.4 Attainment of surfaces that are free of iron, metallicdeposits, and other contamination depends on a combination of
22、proper design, fabrication methods, cleaning and descaling,and protection to prevent recontamination of cleaned surfaces.Meaningful tests to establish the degree of cleanness of asurface are few, and those are often difficult to administer andto evaluate objectively. Visual inspection is suitable fo
23、r thedetection of gross contamination, scale, rust, and particulates,but may not reveal the presence of thin films of oil or residualchemical films. In addition, visual inspection of internalsurfaces is often impossible because of the configuration of theitem. Methods are described for the detection
24、 of free iron andtransparent chemical and oily deposits.1.5 This practice provides definitions and describes prac-tices for cleaning, descaling, and passivation of stainless steelparts. Tests with acceptance criteria to demonstrate that thepassivation procedures have been successful are listed in 7.
25、2.5and 7.3.4, and can also be found in Specification A967/A967M.1.6 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combini
26、ngvalues from the two systems may result in non-conformancewith the standard.1.7 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determ
27、ine the applica-bility of regulatory limitations prior to use. (For more specificsafety precautions see 7.2.5.3, 7.3.4, Section 8, A1.7, andA2.11.)1.8 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision o
28、n Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2A967/A967M Specification for Chemical Passivation Treat-ments for Stainless Steel Parts
29、F21 Test Method for Hydrophobic Surface Films by theAtomizer TestF22 Test Method for Hydrophobic Surface Films by theWater-Break Test2.2 ISO Standards:3ISO 14644-1 Cleanrooms and associated controlled environ-ments - Part 1: Classification of air cleanliness by particleconcentrationISO 14644-2 Clean
30、rooms and associated controlled environ-ments - Part 2: Monitoring to provide evidence ofcleanroom performance related to air cleanliness by par-ticle concentration3. Design3.1 Consideration should be given in the design of parts,equipment, and systems that will require cleaning to minimizethe prese
31、nce of crevices, pockets, blind holes, undrainablecavities, and other areas in which dirt, cleaning solutions, orsludge might lodge or become trapped, and to provide foreffective circulation and removal of cleaning solutions. Inequipment and systems that will be cleaned in place or thatcannot be imm
32、ersed in the cleaning solution, it is advisable toslope lines for drainage: to provide vents at high points anddrains at low points of the item or system; to arrange forremoval or isolation of parts that might be damaged by thecleaning solution or fumes from the cleaning solutions; toprovide means f
33、or attaching temporary fill and circulationlines; and to provide for inspection of cleaned surfaces.3.2 In a complex piping system it may be difficult todetermine how effective a cleaning operation has been. Onemethod of designing inspectability into the system is to providea short flanged length of
34、 pipe (that is, a spool piece) at alocation where the cleaning is likely to be least effective; thespool piece can then be removed for inspection upon comple-tion of cleaning.4. Precleaning4.1 Precleaning is the removal of grease, oil, paint, soil, grit,and other gross contamination preparatory to a
35、 fabricationprocess or final cleaning. Precleaning is not as critical and isgenerally not as thorough as subsequent cleaning operations.Materials are usually precleaned before hot-forming,annealing, or other high-temperature operation, before anydescaling operation, and before any finish-cleaning op
36、erationwhere the parts will be immersed or where the cleaningsolutions will be reused. Items that are subject to severalredraws or a series of hot-forming operations, with intermedi-ate anneals, shall be cleaned after each forming operation, priorto annealing. Precleaning may be accomplished by vapo
37、rdegreasing; immersion in, spraying, or swabbing with alkalineor emulsion cleaners; steam; or high-pressure water-jet (see6.2).5. Descaling5.1 GeneralDescaling is the removal of heavy, tightlyadherent oxide films resulting from hot-forming, heat-treatment, welding, and other high-temperature operati
38、ons.2For 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 onthe ASTM website.3Available from International Organization for Standardiz
39、ation, ISO CentralSecretariat, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva, Switzerland.A380/A380M 172Because mill products are usually supplied in the descaledcondition, descaling (except removal of localized scale result-ing from welding) is generally not necessary during fabricationof eq
40、uipment or erection of systems (see 6.3). When necessary,scale may be removed by one of the chemical methods listedbelow, by mechanical methods (for example, abrasive blasting,sanding, grinding, power brushing), or by a combination ofthese.5.2 Chemical Descaling (Pickling)Chemical descalingagents in
41、clude aqueous solutions of sulfuric acid, or nitric andhydrofluoric acids, as described in Annex A1, Table A1.1,molten alkali or salt baths, and various proprietary formula-tions. The safety precautions of 8.6 shall be observed in the useof these methods. Particular care shall be exercised whenpickl
42、ing closed systems and items with crevices or internalvoids to prevent retention of pickling solutions and residues.5.2.1 Acid PicklingNitric-hydrofluoric acid solution ismost widely used by fabricators of stainless steel equipmentand removes both metallic contamination, and welding andheat-treating
43、 scales. Its use should be carefully controlled andis not recommended for descaling sensitized austenitic stain-less steels or hardened martensitic stainless steels or where itcan come into contact with carbon steel parts, assemblies,equipment, and systems. See also A1.3. Solutions of nitric acidalo
44、ne are usually not effective for removing heavy oxide scale.5.2.2 Surfaces to be descaled shall be precleaned to removeoils and greases prior to acid treatment (see A1.5), and areusually precleaned prior to other chemical treatments.5.2.3 When size and shape of product permit, total immer-sion in th
45、e pickling solution is preferred. Where immersion isimpractical, descaling may be accomplished by (1) wetting thesurfaces by swabbing or spraying, or (2) by partially filling theitem with pickling solution and rotating or rocking to slosh thesolution so that all surfaces receive the required chemica
46、ltreatment. The surface should be kept in contact with agitatedsolution for about 15 to 30 min or until inspection shows thatcomplete scale removal has been accomplished. Withoutagitation, additional exposure time may be required. If rockingor rotation are impracticable, pickling solution may be cir
47、cu-lated through the item or system until inspection shows thatdescaling has been accomplished.5.2.4 Over-pickling must be avoided. Uniform removal ofscale with acid pickling depends on the acid used, acidconcentration, solution temperature, and contact time (seeAnnex A1). Continuous exposure to pic
48、kling solutions formore than 30 min is not recommended. The item should bedrained and rinsed after 30 min and examined to check theeffectiveness of the treatment. Additional treatment may berequired. Most pickling solutions will loosen weld and heat-treating scale but may not remove them completely.
49、 Intermit-tent scrubbing with a stainless steel brush or fiber-bristle brush,in conjunction with pickling or the initial rinse, may facilitatethe removal of scale particles and products of chemicalreaction (that is, pickling smut).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. Aneutralization treatment may be necessary under some condi-tions (such as the presence of crevices). If used, neutralizationis usually also followed by rinsing with
