The pickling and passivation of stainless steel, carbon steel and aluminum products

When it comes to the pickling and passivation of stainless steel, carbon steel and aluminum, our capabilities are second to none. The specialists at Multinal Group are at your service!

Multinal Group has the necessary expertise to effectively pickle and passivate stainless steel products including sheet metal, tubes, piping, assembly parts, grids, frames, pipes, heat exchangers, flanges and housings.

Having several pickling facilities in the Netherlands, we know better than anyone what is involved in the professional handling of your product. In addition to the shape, size and best applicable technology, we are naturally careful to monitor our pickling procedures with regard to the environment, safety and the acid residual treatment. As such you can rest assured that the corrosion resistance, and therefore the durability of your product, will be increased.

You will find our specialist pickling facilities for dip (immersion) or (partial) spray pickling in Amsterdam, Alphen aan den Rijn, Coevorden, Hoogezand and Vlaardingen.

Please view the stainless steel dip and spray tips, and important points of interest for pickling and passivation.


Why pickle and passivate stainless steel?

Stainless steel is protected by a thin chromium oxide layer which forms on the surface of the material by natural means. This chromium oxide layer suffers damage by various mechanical processes such as sawing, cutting, setting, milling and welding. These mechanical processes increase the risks of “iron contamination” on the surface, which may cause the stainless steel to rust in the long run.

By pickling the treated stainless steel in a solution of, for example, nitric acid and hydrofluoric acid, carbides, iron particles, as well as annealing, rolling, forging and milling skin are removed from the surface. After the pickling treatment the parts are thoroughly rinsed, allowing the chromium oxide layer (the passivation) to form naturally again. The formation of this natural passivation can take up to 24-48 hours. With some specifications or customer requirements, an additional process of passivation is required. By dipping the parts in for instance a nitric acid solution for a certain amount of time and thoroughly rinsing them afterwards, the passivation layer will form after just 30 minutes.

We also offer the option of effective (spray or brush) pickling and passivation of stainless steel, piping systems, installations, production units, machinery, boilers, heat exchangers, cooling towers, tanks and other production parts on-site.

With years of experience in on-site pickling and passivation, and multiple pickling facilities across the Netherlands we offer a variety of options. The choice is yours.

Possibilities for pickling and passivation of stainless steel, carbon steel and aluminum

  • Pickling of stainless steel, aluminum and carbon steel according to ASTM A380 standards;
  • Pickling in dipping tanks, spray shoots or on-site;
  • Support and preparation of specific pickling procedures for your client;
  • Pickling treatment also possible according to the standards of your client;
  • Multinal Group has several specialist pickling facilities.

You can see the before and after picture by clicking the white arrow in the middle of the picture, and drag it to the right (keep your left mouse button pushed down).

Pictures of a part before the pickling process and after the pickling treatment conducted by Multinal Group.

Kind of metal, size and applicable method of pickling

When you have to pickle metal the kind of metal, the shape, size and applicable method are very important. Obvious a difficult to move object has to be pickled on site, in contrast to an easy movable object which can be pickled in our factory. Also safety, environment and our expertise are very important issues.

A clean and pure surface

Regardless which treatment you choose, the pickling treatment is aimed to remove the oxides which were formed during warmth treatments or production. You can think about mill scale, welding scale, discolorations and removal of rust. By cleaning the object thoroughly with demineralised water we obtain a clear and pure surface.

Passivation: optimum resistance against corrosion

When there is a high degree of pollution and/ or high quality requirements we advise you to pickle and passivate separately. It is an important process to passivate after a pickle treatment, because the corrosion resistance will be optimal. You can execute a passivate treatment or you can accelerate this process with chemical passivation. We apply chemical passivation frequently as we like to obtain short delivery times and to guarantee the required quality.

The treatments of pickling and passivation of stainless steel, carbon steel, and aluminum