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Citric acid is usually associated with passivation, not aggressive pickling. It removes free iron and surface contamination and promotes a strong chromium oxide passive film, but on its own it generally does not remove heavy weld scale or heat tint as effectively as nitric/hydrofluoric pickling.

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Advantages:

• Safer to handle than nitric/hydrofluoric acid systems.

• More environmentally friendly.

• Lower fumes and easier waste management.

• Effective for passivating many stainless grades.

• Commonly recognised in ASTM A967 for chemical passivation.
  
   

Disadvantages:

• Not normally strong enough for heavy pickling by itself.

• May not remove weld heat tint, heavy scale, or chromium-depleted layers.

• May require longer treatment times, elevated temperatures, or fluoride additives for pickling-style results.
   

For heavily welded or oxidised stainless steel, our nitric/hydrofluoric pickling remains the more powerful option; for clean stainless components requiring corrosion protection, citric acid passivation is often the safer and cleaner choice.