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Stainless Steel Passivation:

ASTM A967 – ASTM A380
Carolina Piping Services is also a leader in passivation of stainless steel services using both citric and nitric acid methods to ASTM A967 standards. Carolina Piping Services can provide passivation services of stainless steel across the Medical and Industrial Fields of service.


The passivation process returns the stainless steel or other metals back to its original specifications by removing unwanted debris and oils from the surface and then submerging the part into a passivating bath. When a part is machined, various particles can permeate the surface of the base metal, weakening its resistance to corrosion and making the part more susceptible to environmental factors. Debris, dirt and other particles and residue such as free iron, grease and machining oils all affect the strength of the natural surface and can become embedded in the surface during the machining process. These often go unseen to the human eye and are often the cause of the deterioration. As stated above, “passive” is defined as being less affected by environmental factors. The process improves and purifies the surface of the part. The restored surface acts like a protective coating to environmental factors such as air, water and other extreme environments. It is important to note that passivation does not change the outward appearance of the base metal.


Advantages of Passivation

  • Improved Corrosion Resistance

  • Uniform, Smooth Appearance & Finish

  • Deburring (Polished Surface)

  • Cleanliness

  • Improved & Extended Life of Product


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 is already known as being corrosion-resistant, however the passivation process further strengthens its’ natural coating by improving the exterior surface of the overall part. Stainless steel passivation unipotentializes the stainless steel with the oxygen absorbed by the metal surface, creating a mono-molecular oxide film. Passivation can result in the very much-desired low corrosion rate of the metal.

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