Cleaning of Rouge and Passivation of Stainless

Q: We have a stainless steel large tank and a piping system with rouge cleaning and passivation needs. Requiring a low foaming detergent, as we will run a CIP system. Can Alconox Inc. assist?

A: Rouge is the formation of iron oxide or hydroxide on stainless steel, often created by a corrosive over time or improper passivation efforts.   To clean rouge we recommend a hot (65C / 150F or hotter) 3% Keylajet® Low-foaming Chelating High Alkaline Liquid solution be circulated and exposed to the system being derouged for 15 minutes. For a 3000L solution you will need 90L or Keylajet or 24 gallons of Keylajet. Flush with water before passivating.

Passivate using Citrajet® Low-Foam Liquid Acid Cleaner/Rinse according as discussed in our citric acid passivation TechNote article using a 30% dilution (300 mL/L) at the times and temperature discussed. For a 3000L solution you will need 900L of Citrajet or 237 gallons of Citrajet (roughly 4×55 gal drums + 1×15 gal drum). Follow with a water rinse.

A helpful technique is that you can blend the used Keylajet and used Citrajet to neutralize. After blending these, there will still be considerable acidity from the citric acid in Citrajet detergent. Some local requirements may mandate further neutralization.  To neutralize this you can use use sodium carbonate (washing soda – not baking soda). Add slowly, as this will get hot and will bubble off carbon dioxide as it neutralizes. Avoid bringing the solution to boiling temperatures. Rinse thoroughly after neutralizing. 

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