INOX Surface Treatment BV

Specialists in stainless steel and carbon steel surface treatment.

  

Inox Surface Treatment B.V.

Industrieweg 9b

3286BW Klaaswaal

The Netherlands

Tel: +31 (0) 186 - 572 443

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VCA certificate

    

PICKLING & PASSIVATION

The need for cleaning
A good stainless steel surface is clean, smooth and has no defects. A smooth surface finish is also crucial to corrosion resistance. Stainless Steel has a passive (protective) chromium oxide layer which protects the stainless steel from corrosion. When this passive layer is damaged , the surface will become active and therefore not corrosion resistant.

Corrosion
Corrosion of stainless steel can be caused by several defects in and on the surface, such as:
- Heat Affected Zones (HAZ) due to welding
- Weld defects
- Iron Contamination
- Rough Surface
- Organic contamination
- Aggressive chemicals

Pre-cleaning
Before carrying out pickling and/or passivation procedure, pre-cleaning can be necessary to make sure the surface is free of grease, oil, dirt, atmospheric pollution. This way the pickling agent has an optimal accessibility to the surface which needs to be treated by pickling.

Pickling
Pickling process removes a thin surface layer from the stainless steel, using an acid solution, which is usually a hydrofluoric and nitric acid mixture. Different kinds of stainless steel require different kinds of mixtures. Furthermore for the pickling to be effective the surface should be clean and free of greases and oils. Pickling will remove embedded iron, surface iron contamination, heat tint and weld scale.

Passivation
Passivation process is a separate/different process to pickling. It can be carried out as an independent process or as part of pickling involving nitric acid in the solution. In this case passivation occurs sequentially and not simultaneously. Nitric acid or citric acid are the usual strong oxidizing agents used for chemical passivation. On its own it will only remove free iron contamination from the stainless steel surface and is not an effective acid for pickling stainless steel.

INOX will be at your service for your surface 24/7 worldwide



Before and after pickling
SUS Pipe lines - Before Pickling Passivation
SUS Pipe lines -After Pickling Passivation



Before pickling
After pickling
After pickling