Cleaning, Descaling, and Passivation of Stainless Steel This standard is issued under the fixed designation A; the number immediately. Pickling, passivation and removing iron contamination with nitric acid ASTM A – Practice for Cleaning, Descaling and Passivating of Stainless Steel Parts, . Passivation per ASTM A Posted on November 29, Latest News. APT to Exhibit at SHOT Show in Las Vegas, NV. Advanced Plating.
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Some of the various meanings associated with the term passivation that are in common usage include the following:. Scales shall be removed through chemical descaling, acid pickling, and mechanical descaling. Pickling, passivation and removing iron contamination with nitric acid Passivation treatments are sometimes specified, but it is important to consider whether this is strictly necessary or not.
Passivation is a process that removes exogenous iron or iron compounds from the surface of the stainless steel alloy.
ASTM A380 Passivation Standard
Naturally occurring conditions such air or aerated water will do this and so under many exposure conditions stainless steels will naturally self-passivate. The standard also allows any combination of citric acid concentration, temperature and time, provided that the passivation test criteria can be met.
This ensures that the surface of the workpiece is free of scale and contaminates. Unlike ASTM A, the standard does not require specific solutions for particular stainless steel grades or types, although 3 specific treatments are identified. Range C Time mins. This formula should not hurt your electropolished surfaces. Process Class Stainless Steel Types C1 or C2 Austenitics, austenitic precipitation hardening and duplex C3 High chromium martensitics C4 Ferritics, martensitics and martensitic precipitation hardening.
Visual inspection; wipe tests; residual pattern; water-break test; free iron test such as water-wetting or drying; high-humidity test; and copper sulfate test. I am not sure exactly what you want to do, but the citric formulations can give you increased performance over the old nitric formulations.
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Passivation is a post-fabrication method of maximizing the inherent corrosion resistance of stainless steel. Others, such as food-handling, pharmaceutical, aerospace, and certain nuclear applications, may require extremely high passivatiion of cleanness, including removal of all detectable residual chemical films and contaminants that are invisible to ordinary inspection methods. If the piping system is passivatlon assembled, there are service companies which specialize in on-site projects pawsivation this sort, like Astropak.
I believe you must pickle the spools with an acid which contains fluoride in some form — often a standard nitric-hydrofluoric pickling acid or pwssivation paste, and follow this either with electropolishing or with qstm acid passivation or citric acid passivation to the standards discussed above.
All information presented is for general reference and does not represent a professional opinion nor the policy of an author’s employer. Passivation of stainless steels Introduction Stainless steels are designed to naturally self-passivate whenever a clean surface is exposed to an environment that can provide enough oxygen to form the chromium rich oxide surface layer, on which the corrosion resistance of these alloys depends. It’s not possible to diagnose a finishing problem or the hazards of an operation via these pages.
I think you may be thinking of ammonium hydrogen difluoride which is often used in place of hydrofluoric acid in pickle solutions. It therefore in no way precludes the necessity for careful planning and judgment in the selection and implementation of such procedures.
ASTM A Passivation Standard | Able Electropolishing
Asgm process is described in pssivation general way in 6. Unless otherwise specified, it is this definition of passivation that is taken as the meaning of a specified requirement for passivation.
Historical Version s – view previous versions of standard. These recommendations are presented 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.
This abstract is a brief summary of the referenced standard. The degree of cleanness required on a surface depends on the application. Keystone Corporation is an industry leader in the passivation of stainless steel. From beautiful Pine Beach New Jersey: The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other.
This standard covers both nitric and citric acid treatments. You do not need super quality water for these processes; DI or RO aastm will be fine. On the other hand, some of the practices may be applicable for these purposes.
Usually it is best to send the spools to a metal finishing shop which is already experienced in and equipped for the process. Parts treated however must pass specific tests to confirm the effectiveness of the passivation, although in practice the tests are for the detection of the effects of residual iron q380 on the surface of the parts.
For certain exceptional applications, additional requirements which are not covered by this axtm may be specified upon agreement between the supplier and the purchaser.
Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard. Although they apply primarily to materials in the composition ranges of the austenitic, ferritic, martensitic, and duplex stainless steels, the practices described may also be useful for cleaning other metals if due consideration is given to corrosion and possible metallurgical effects. Citric acid is a less hazardous method and has environmental benefits in terms of ‘NOx’ fume emission and waste acid disposal.
It is informational only and not an official part of the standard; the full text of the standard itself must be referred to for its use and application.