The Passivation Process
Passivation is a two-step procedure: Cleaning and Passivating treatment in an acid bath.
Cleaning: grease, oil and shop debris and dirt must be carefully removed from the part by wiping with or immersion in an alkaline solution.
Passivation: once cleaned, the part is immersed in a nitric acid/ water solution in which the nitric acid is 20-45% by volume. Nitric acid, by virtue of its ability to dissolve iron particles, allows the material of the part to regain its “stainlessness”. This means that the oxide film will once again form over the whole part, maximizing its corrosion resistance.
Passivation Specifications applicable to work done by Electro-Kleen:
ASTM A380-99 Standard Practice for Cleaning, Descaling and Passivation of Stainless Steel Parts, Equipment and Systems.
ASTM A 967 Chemical Passivation Treatments for Stainless Steel Parts
For more information, contact Electro-Kleen.