On-site services

Pickling and passivation of stainless steel systems and installations

Prevent contamination of the process or medium in the installation or system

Stainless steel systems and installations are periodically cleaned before commissioning and in many cases to remove process contamination such as scale.

Metal surface treatment

Stainless steel must be chemically cleaned before use. The corrosion resistance of stainless steel is determined by a chromium-rich oxide skin. Once this oxide skin is formed, there is a passive surface.

Corrosion

Stainless steel is not completely resistant to corrosion. It is important that light corrosion is removed to prevent, among other things, pit corrosion with all associated negative consequences and to prevent contamination of the process or medium in the installation or system.

Why pickling and passivating

During the installation of the stainless steel pipes in a system and / or installation, the surface is exposed to many mechanical and thermal treatments. This causes damage to and contamination of the protective oxide skin. This results in the loss of corrosion-resistant properties. The base material will therefore corrode faster. It is therefore very important that the chromium-rich oxide skin is intact and clean before the system or installation is put into use.

Pre-commissioning cleaning

Pre-commissioning cleaning of austenitic stainless steel generally involves three steps: degreasing, pickling and passivating. Degreasing is necessary to remove oil, grease and atmospheric contamination and to make the surface optimally accessible for the pickling agent. The pickling treatment removes iron particles and other contaminants from previous treatments on the material such as welding, handling, etc. After pickling, the material is rinsed with low-chloride water to remove acid residues. The pickling treatment results in a chrome-rich surface.

Although the stainless steel will spontaneously passivate after pickling (forming a protective chromium oxide film) by exposure to sufficient oxygen in the outside air, closed systems are generally chemically passivated. The passivation fluid is circulated through the installation or system using acid-resistant pump units. The duration of this treatment depends on the type of stainless steel and the temperature. Analysis of the iron content and acid concentrations determine when the treatment is complete. The treatment is followed by rinsing, first with drinking water and then with demineralised water.

On-site services

Pre-commissioning cleaning

Prior to the commissioning of systems and installations, the metal surface is cleaned to restore it after opeations like welding and grinding.

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Post-commissioning cleaning

Increase the efficiency of steam boilers to at least 90% through chemical technical cleaning.

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Boiler cleaning

At power plants, the purity of the steam quality is essential. If the steam contains impurities, these can deposit on the turbine blades.

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Cleaning of urea strippers

The consequence of the typical deposition in a urea stipper is a reduced heat transfer, making the production process less efficient.

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De-rouging

The cleaning of stainless steel in the pharmaceutical industry is very important because hygiene is a very high priority here.

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Pipe pigging

Efficient internal cleaning of transport pipes while the piping system remains operational. More than 90% chemical waste reduction.

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For more information or questions, contact one of our specialists.