ASTM A380-06

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Designation: A380 − 06
StandardPractice for
Cleaning, Descaling, and Passivation of Stainless Steel
1
Parts, Equipment, and Systems
This standard is issued under the fixed designation A380; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber 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 Department of Defense.
1. Scope* acid solution that will remove the surface contamination but
will not significantly affect the stainlees steel itself. This
1.1 This practice covers recommendations and precautions
process is described in a general way in 6.2.11 and defined
for cleaning, descaling, and passivating of new stainless steel
precisely in 6.4 with further reference to the requirements of
parts, assemblies, equipment, and installed systems. These
Annex A2 and Part II of the table on acid cleaning of steel.
recommendations are presented as procedures for guidance
Unless otherwise specified, it is this definition of passivation
when it is recognized that for a particular service it is desired
that is taken as the meaning of a specified requirement for
to remove surface contaminants that may impair the normal
passivation.
corrosion resistance, or result in the later contamination of the
1.1.1.3 Passivation is the chemical treatment of a stainless
particularstainlesssteelgrade,orcauseproductcontamination.
steel with a mild oxidant, such as a nitric acid solution, for the
For certain exceptional applications, additional requirements
purpose of enhancing the spontaneous formation of the protec-
which are not covered by this practice may be specified upon
tive passive film. Such chemical treatment is generally not
agreement between the manufacturer and the purchaser. Al-
necessary for the formation of the passive film.
though they apply primarily to materials in the composition
ranges of the austenitic, ferritic, and martensitic stainless
1.1.1.4 Passivation does not indicate the separate process of
steels, the practices described may also be useful for cleaning
descalingasdescribedinSection5,althoughdescalingmaybe
other metals if due consideration is given to corrosion and
necessary before passivation can be effective.
possible metallurgical effects.
1.2 This practice does not cover decontamination or clean-
1.1.1 The term passivation is commonly applied to several
ingofequipmentorsystemsthathavebeeninservice,nordoes
distinctly different operations or processes relating to stainless
it cover descaling and cleaning of materials at the mill. On the
steels. In order to avoid ambiguity in the setting of
other hand, some of the practices may be applicable for these
requirements, it may be necessary for the purchaser to define
purposes. While the practice provides recommendations and
precisely the intended meaning of passivation. Some of the
informationconcerningtheuseofacidsandothercleaningand
various meanings associated with the term passivation that are
descaling agents, it cannot encompass detailed cleaning proce-
in common usage include the following:
dures for specific types of equipment or installations. It
1.1.1.1 Passivation is the process by which a stainless steel
thereforeinnowayprecludesthenecessityforcarefulplanning
will spontaneously form a chemically inactive surface when
and judgment in the selection and implementation of such
exposedtoairorotheroxygen-containingenvironments.Itwas
procedures.
at one time considered that an oxidizing treatment was neces-
sary to establish this passive film, but it is now accepted that
1.3 These practices may be applied when free iron, oxide
this film will form spontaneously in an oxygen-containing
scale,rust,grease,oil,carbonaceousorotherresidualchemical
environment providing that the surface has been thoroughly
films, soil, particles, metal chips, dirt, or other nonvolatile
cleaned or descaled.
deposits might adversely affect the metallurgical or sanitary
1.1.1.2 Passivation is removal of exogenous iron or iron
condition or stability of a surface, the mechanical operation of
compounds from the surface of a stainless steel by means of a
a part, component, or system, or contaminate a process fluid.
chemical dissolution, most typically by a treatment with an
The degree of cleanness required on a surface depends on the
application.Insomecases,nomorethandegreasingorremoval
1
of gross contamination is necessary. Others, such as food-
This practice is under the jurisdiction of ASTM Committee A01 on Steel,
Stainless Steel and RelatedAlloysand is the direct responsibility of Subcommittee
handling, pharmaceutical, aerospace, and certain nuclear
A01.14 on Methods of Corrosion Testing.
ap
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