Passivating Stainless Steel Tanks with Citric Acid

The “stainless” in stainless steel is a very thin layer of oxidation, only a few molecules thick. Surface damage will compromise the oxidation. Exposure to acidic liquids or salt will eventually degrade the layer of oxidation, leaving it vulnerable to rust and corrosion.
Passivation of stainless steel re-establishes the layer of oxidation. It happens naturally through exposure to air. Citric acid is a quick and effective way to passivate stainless steel.

  • Use a 4% solution: 40g of citric acid per litre of warm water.
  • 60°C is the ideal temperature, but a range of 40-60°C is effective.

    How to Passivate Stainless Steel Equipment
  1. Clean thoroughly and rinse to remove any cleaning chemical residue. TSP is a good choice of cleaner
    for this procedure.
  2. Fill with the citric acid solution. Leave the solution in the tank for 2 hours.
  3. Drain the solution. Do not rinse. Allow the tank to air-dry for 12-24 hours.
  4. Clean and sanitize the tank as usual. It is now ready to use.
    The citric acid solution can be stored and re-used for up to a year.

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