MLS Pickling & Passivation

Let’s keep it easy & simple!

They are two distinctly different processes. Pickling removes the oxide layer and Passivation restores the oxide layer.

Post-treatment in practice

Post-treatment should always begin with cleaning and degreasing. Optimally, the process then continues with pickling. This can be done with gels, pastes and sprays or by immersion in a bath. In certain cases, a final treatment with a passivation agent may be necessary. After each step in the process, the object being treated must always be rinsed using water at high pressure. In accordance with good environmental practice, the rinse water must be taken care of as stipulated in relevant laws and regulations.

Pickling

Pickling is a process where a stainless steel object is subjected to some form of acid treatment. The common type acids are usually a mixture of Hydrofluoric and Nitric acid.

This removes the very thin passive or chromium oxide layer which may have been affected by heat from thermal cutting and welding or other mechanical processes such as rolling, bending, guillotining and punching leaving a fully alloyed surface.

* These acids are extremely dangerous if not used correctly and by trained personnel.

Safety is important when pickling

Pickling chemicals are harzardous substances so the user must be protected against fumes and splashes. Follow these general guidelines and safety levels when working with any pickling products.

Safety data Sheet should always be evaluated before chemicals are used.

Passivation

Passivation is the restoration by chemical means of the thin passive layer or chromium enriched oxide layer. This layer gives stainless steels its corrosion resistance.

MLS often sees specifications and documents asking for materials to be passivated but they have not asked for the material to be pickled.  This is where people get confused and often get the wrong products or result.

Passivation products are usually Citric or Nitric acid based, there are other formulas that are non-acid based available in the market place.

Would you like to get pickled and passivated?

Contact Mr. Chintan Patel from Marks Pickling and Passivation Service on info@markslifesaving.com to discuss your next chemical cleaning, pickling, passivation and electro polishing requirements.