Passivation

Restoring Passive Layer on Austenitic Stainless Steels

Passivation chemically removes free iron and surface contaminants from stainless steel surfaces, promoting the formation of a uniform, protective chromium oxide layer. This enhances corrosion resistance and reduces the risk of contamination in critical systems.

AEKS performs on-site passivation using:

• Nitric acid passivation (per ASTM A967, A380, EN 2516)
• Citric acid passivation for more sensitive environments or where nitric is prohibited
• Neutralization and deionized water rinsing to ensure residue-free finishes

Surface preparation steps often include:

• Degreasing
• Pickling (where necessary)
• Pre-cleaning with alkaline solutions

Post-passivation validation may involve:

• Ferroxyl testing or copper sulfate tests
• Koslow
• Surface roughness measurements
• Material traceability documentation
• Customized method statement and risk assessment (RAMS)
• Full GDP-compliant reporting package

Passivation is crucial for new stainless steel process systems, or following welding, grinding, or de-rouging treatments.