Standard Practice for
Cleaning, Descaling, and Passivation of Stainless Steel Parts, Equipment, and Systems1
This standard is issued under the ﬁxed designation A 380; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of lastreapproval. 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 Department of Defense.
1. Scope* 1.1 This practice covers recommendations and precautions for cleaning, descaling, and passivating of new stainless steel parts, assemblies, equipment, and installed systems. These recommendations arepresented as procedures for guidance 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. For certain exceptional applications, additional requirements which are not covered by this practice may bespeciﬁed upon agreement between the manufacturer and the purchaser. Although they apply primarily to materials in the composition ranges of the austenitic, ferritic, and martensitic stainless steels, the practices described 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 is commonly applied toseveral distinctly different operations or processes relating to stainless steels. In order to avoid ambiguity in the setting of requirements, it may be necessary for the purchaser to deﬁne precisely the intended meaning of passivation. Some of the various meanings associated with the term passivation that are in common usage include the following: 184.108.40.206 Passivation is the process by which astainless steel will spontaneously form a chemically inactive 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 ﬁlm, but it is now accepted that this ﬁlm will form spontaneously in an oxygen-containing environment providing that the surface has been thoroughly cleaned or descaled.
1 Thispractice is under the jurisdiction of ASTM Committee A01 on Steel, Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee A01.14 on Methods of Corrosion Testing. Current edition approved May 1, 2006. Published May 2006. Originally approved in 1954. Last previous edition approved in 2005 as A 380 – 99 (2005).
220.127.116.11 Passivation is removal of exogenous iron or ironcompounds from the surface of a stainless steel by means of a chemical dissolution, most typically by a treatment with an acid solution that will remove the surface contamination but will not signiﬁcantly affect the stainlees steel itself. This 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 tableon acid cleaning of steel. Unless otherwise speciﬁed, it is this deﬁnition of passivation that is taken as the meaning of a speciﬁed requirement for passivation. 18.104.22.168 Passivation 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 protective passive ﬁlm. Such chemical treatment isgenerally not necessary for the formation of the passive ﬁlm. 22.214.171.124 Passivation does not indicate the separate process of descaling as described in Section 5, although descaling may be necessary before passivation can be effective. 1.2 This practice does not cover decontamination or cleaning of equipment or systems that have been in service, nor does it cover descaling and cleaning of materials at...