1、Designation: A380 06A380/A380M 13Standard Practice forCleaning, Descaling, and Passivation of Stainless SteelParts, Equipment, and Systems1This standard is issued under the fixed designationA380;A380/A380M; the number immediately following the designation indicates theyear of original adoption or, i
2、n the case of revision, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1
3、This practice covers recommendations and precautions for cleaning, descaling, and passivating of new stainless steel parts,assemblies, equipment, and installed systems. These recommendations are presented as procedures for guidance when it isrecognized that for a particular service it is desired to
4、remove surface contaminants that may impair the normal corrosionresistance, or result in the later contamination of the particular stainless steel grade, or cause product contamination. The selectionof procedures from this practice to be applied to the parts may be specified upon agreement between t
5、he supplier and the purchaser.For certain exceptional applications, additional requirements which are not covered by this practice may be specified uponagreement between the manufacturersupplier and the purchaser. Although they apply primarily to materials in the compositionranges of the austenitic,
6、 ferritic, and martensitic stainless steels, the practices described may also be useful for cleaning other metalsif due consideration is given to corrosion and possible metallurgical effects.1.1.1 The term passivation is commonly applied to several distinctly different operations or processes relati
7、ng to stainless steels.In order to avoid ambiguity in the setting of requirements, it may be necessary for the purchaser to define precisely the intendedmeaning of passivation. Some of the various meanings associated with the term passivation that are in common usage include thefollowing:1.1.1.1 Pas
8、sivation is the process by which a stainless steel will spontaneously form a chemically inactive surface when exposedto air or other oxygen-containing environments. It was at one time considered that an oxidizing treatment was necessary toestablish this passive film, but it is now accepted that this
9、 film will form spontaneously in an oxygen-containing environmentproviding that the surface has been thoroughly cleaned or descaled.1.1.1.2 Passivation is removal of exogenous iron or iron compounds from the surface of a stainless steel by means of a chemicaldissolution, most typically by a treatmen
10、t with an acid solution that will remove the surface contamination but will not significantlyaffect the stainleesstainless steel itself. This process is described in a general way in 6.2.11 and defined precisely in 6.4 with furtherreference to the requirements of Annex A2 and Part II of the table on
11、 acid cleaning of steel. Unless otherwise specified, it is thisdefinition of passivation that is taken as the meaning of a specified requirement for passivation.1.1.1.3 Passivation is the chemical treatment of a stainless steel with a mild oxidant, such as a nitric acid solution, for thepurpose of e
12、nhancing the spontaneous formation of the protective passive film. Such chemical treatment is generally not necessaryfor the formation of the passive film.1.1.1.4 Passivation does not indicate the separate process of descaling as described in Section 5, although descaling may benecessary before pass
13、ivation can be effective.1.2 This practice does not cover decontamination or cleaning of equipment or systems that have been in service, nor does itcover descaling and cleaning of materials at the mill. On the other hand, some of the practices may be applicable for these purposes.While the practice
14、provides recommendations and information concerning the use of acids and other cleaning and descaling agents,it cannot encompass detailed cleaning procedures for specific types of equipment or installations. It therefore in no way precludesthe necessity for careful planning and judgment in the selec
15、tion and implementation of such procedures.1.3 These practices may be applied when free iron, oxide scale, rust, grease, oil, carbonaceous or other residual chemical films,soil, particles, metal chips, dirt, or other nonvolatile deposits might adversely affect the metallurgical or sanitary condition
16、 orstability of a surface, the mechanical operation of a part, component, or system, or contaminate a process fluid. The degree of1 This practice is under the jurisdiction of ASTM Committee A01 on Steel, Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee A01.14on Met
17、hods of Corrosion Testing.Current edition approved May 1, 2006. Published May 2006. Originally approved in 1954. Last previous edition approved in 2005 as A380 99 (2005). DOI:10.1520/A0380-06.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indica
18、tion of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be con
19、sidered the official document.*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 States1cleanness required on a surface depends on the application. In some cases, no more than deg
20、reasing or removal of grosscontamination is necessary. Others, such as food-handling, pharmaceutical, aerospace, and certain nuclear applications, mayrequire extremely high levels of cleanness, including removal of all detectable residual chemical films and contaminants that areinvisible to ordinary
21、 inspection methods.NOTE 1The term “iron,” when hereinafter referred to as a surface contaminant, shall denote free iron.1.4 Attainment of surfaces that are free of iron, metallic deposits, and other contamination depends on a combination of properdesign, fabrication methods, cleaning and descaling,
22、 and protection to prevent recontamination of cleaned surfaces. Meaningfultests to establish the degree of cleanness of a surface are few, and those are often difficult to administer and to evaluate objectively.Visual inspection is suitable for the detection of gross contamination, scale, rust, and
23、particulates, but may not reveal the presenceof thin films of oil or residual chemical films. In addition, visual inspection of internal surfaces is often impossible because of theconfiguration of the item. Methods are described for the detection of free iron and transparent chemical and oily deposi
24、ts.1.5 This practice provides definitions and describes good pratices practices for cleaning, descaling, and passivation of stainlesssteel parts, but does not provide tests parts. Tests with acceptance criteria to demonstrate that the passivation procedures have beensuccessful. For such tests, itsuc
25、cessful are listed in 7.2.5 is appropriateand 7.3.4 to specify one of the practices listed in and canalso be found in Specification A967.1.6 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in eachsystem may not be exact equivalent
26、s; therefore, each system shall be used independently of the other. Combining values from thetwo systems may result in non-conformance with the standard.1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of t
27、his standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. (For more specific safety precautions see 7.2.5.3, 7.3.4, Section 8, A1.7, and A2.11.)2. Referenced Documents2.1 ASTM Standards:2A967 Specification for Chemical Pa
28、ssivation Treatments for Stainless Steel PartsF21 Test Method for Hydrophobic Surface Films by the Atomizer TestF22 Test Method for Hydrophobic Surface Films by the Water-Break Test2.2 Federal Standard:3Fed. Std. No. 209e for Clean Room and Work Station Requiring Controlled Environments3. Design3.1
29、Consideration should be given in the design of parts, equipment, and systems that will require cleaning to minimize thepresence of crevices, pockets, blind holes, undrainable cavities, and other areas in which dirt, cleaning solutions, or sludge mightlodge or become trapped, and to provide for effec
30、tive circulation and removal of cleaning solutions. In equipment and systems thatwill be cleaned in place or that cannot be immersed in the cleaning solution, it is advisable to slope lines for drainage: to providevents at high points and drains at low points of the item or system; to arrange for re
31、moval or isolation of parts that might bedamaged by the cleaning solution or fumes from the cleaning solutions; to provide means for attaching temporary fill andcirculation lines; and to provide for inspection of cleaned surfaces.3.2 In a complex piping system it may be difficult to determine how ef
32、fective a cleaning operation has been. One method ofdesigning inspectability into the system is to provide a short flanged length of pipe (that is, a spool piece) at a location where thecleaning is likely to be least effective; the spool piece can then be removed for inspection upon completion of cl
33、eaning.4. Precleaning4.1 Precleaning is the removal of grease, oil, paint, soil, grit, and other gross contamination preparatory to a fabrication processor final cleaning. Precleaning is not as critical and is generally not as thorough as subsequent cleaning operations. Materials shouldbe precleaned
34、 before hot-forming, annealing, or other high-temperature operation, before any descaling operation, and before anyfinish-cleaning operation where the parts will be immersed or where the cleaning solutions will be reused. Items that are subjectto several redraws or a series of hot-forming operations
35、, with intermediate anneals, must be cleaned after each forming operation,prior to annealing. Precleaning may be accomplished by vapor degreasing; immersion in, spraying, or swabbing with alkaline oremulsion cleaners, steam, or high-pressure water-jet (see 6.2).2 For referencedASTM standards, visit
36、theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 Available from Standardization Documents Order Desk, Bldg 4 Section D, 700 Robbins Ave., Philadel
37、phia, PA 19111-5094, Attn: NPODS.A380/A380M 1325. Descaling5.1 GeneralDescaling is the removal of heavy, tightly adherent oxide films resulting from hot-forming, heat-treatment,welding, and other high-temperature operations. Because mill products are usually supplied in the descaled condition, desca
38、ling(except removal of localized scale resulting from welding) is generally not necessary during fabrication of equipment or erectionof systems (see 6.3). When necessary, scale may be removed by one of the chemical methods listed below, by mechanical methods(for example, abrasive blasting, sanding,
39、grinding, power brushing), or by a combination of these.5.2 Chemical Descaling (Pickling)Chemical descaling agents include aqueous solutions of sulfuric, nitric, and hydrofluoricacid as described in Annex A1, Table A1.1, molten alkali or salt baths, and various proprietary formulations.5.2.1 Acid Pi
40、cklingNitric-hydrofluoric acid solution is most widely used by fabricators of stainless steel equipment andremoves both metallic contamination, and welding and heat-treating scales. Its use should be carefully controlled and is notrecommended for descaling sensitized austenitic stainless steels or h
41、ardened martensitic stainless steels or where it can come intocontact with carbon steel parts, assemblies, equipment, and systems. See also A1.3. Solutions of nitric acid alone are usually noteffective for removing heavy oxide scale.5.2.2 Surfaces to be descaled are usually precleaned prior to chemi
42、cal treatment. When size and shape of product permit, totalimmersion in the pickling solution is preferred. Where immersion is impractical, descaling may be accomplished by (1) wettingthe surfaces by swabbing or spraying; or (2) by partially filling the item with pickling solution and rotating or ro
43、cking to slosh thesolution so that all surfaces receive the required chemical treatment. The surface should be kept in contact with agitated solutionfor about 15 to 30 min or until inspection shows that complete scale removal has been accomplished. Without agitation, additionalexposure time may be r
44、equired. If rocking or rotation are impracticable, pickling solution may be circulated through the item orsystem until inspection shows that descaling has been accomplished.5.2.3 Over-pickling must be avoided. Uniform removal of scale with acid pickling depends on the acid used, acid concentration,s
45、olution temperature, and contact time (see Annex A1). Continuous exposure to pickling solutions for more than 30 min is notrecommended. The item should be drained and rinsed after 30 min and examined to check the effectiveness of the treatment.Additional treatment may be required. Most pickling solu
46、tions will loosen weld and heat-treating scale but may not remove themcompletely. Intermittent scrubbing with a stainless steel brush or fiber-bristle brush, in conjunction with pickling or the initial rinse,may facilitate the removal of scale particles and products of chemical reaction (that is, pi
47、ckling smut).5.2.4 After chemical descaling, surfaces must be thoroughly rinsed to remove residual chemicals; a neutralization step issometimes necessary before final rinsing. To minimize staining, surfaces must not be permitted to dry between successive stepsof the acid descaling and rinsing proced
48、ure, and thorough drying should follow the final water rinse. Chemical descaling methods,factors in their selection, and precautions in their use are described in the Metals Handbook.4 When chemical descaling isnecessary, it should be done while the part is in its simplest possible geometry, before
49、subsequent fabrication or installation stepscreate internal crevices or undrainable spaces that may trap descaling agents, sludge, particles, or contaminated rinse water thatmight either result in eventual corrosion or adversely affect operation of the item after it is placed in service.5.3 Mechanical DescalingMechanical descaling methods include abrasive blasting, power brushing, sanding, grinding, andchipping. Procedural requirements and precautions for some of these methods are given in the Metals Handbook.4 Mechanicaldescaling methods have the advantage that they do not p
copyright@ 2008-2019 麦多课文库（www.mydoc123.com）网站版权所有
备案/许可证编号：苏ICP备17064731号-1