Stainless Steel Passivation |
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In years gone by, the process specified was to "pickle and passivate"
- a two step method - in order to create a surface on stainless steel
that would be resistant to corrosion. Today, we differentiate between
the two. It is two separate processes. Pickling (or Chemical Descaling) is done to remove scale. Passivation of stainless steel is done to
make the surface more passive and corrosion resistant.
 Stainless
Passivation
The passivation of stainless steel is a process performed to make a surface passive, i.e., a
surface film is created that causes the surface to lose its chemical reactivity.
Stainless steel passivation unipotentializes the stainless steel with the oxygen absorbed
by the metal surface, creating a monomolecular oxide film. Passivation
can result in the very much-desired low corrosion rate of the metal.
The passivation of stainless steel is performed when free iron, oxide scale, rust, iron particles,
metal chips or other nonvolatile deposits might adversely affect the metallurgical
or sanitary condition or stability of the surface, the mechanical operation
of a part, component or system, or contaminate the process fluid.
Passivation is performed on clean stainless steel, providing the surface
has been thoroughly cleaned or descaled. Since the term "passivation"
is used to describe distinctly different operations or processes relating
to stainless steels, it is necessary to define precisely what is meant
by passivation.
Click here to learn more about the stainless steel passivation process.
Stainless Passivation Specifications in use at Delstar:
- ASTM A 967, Chemical Passivation Treatments for Stainless Steel
Parts
- ASTM A 380, Standard Practice for Cleaning, Descaling, and Passivation
of Stainless Steel Parts, Equipment and Systems
- Federal Specification QQ-P-35C, Passivation Treatments for Corrosion
Resistant Steels
- ASTM B 912, Passivation of Stainless Steels Using Electropolishing
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