Contamination (rouge) and corrosion of the internal surface of tanks is common in the most varied industries that use stainless steel in their installations. Both problems are worrying because they condemn the main property of stainless steel: its passivity. The passivity of stainless steel is related to the passive film of chromium oxide, which can be progressively dissolved in media containing aggressive ions (such as chloride), reducing media (pH>8), or scale and corrosion products adhered to the surface such as rouge or biofilm contamination. 

ACW Engenharia offers the state-of-the-art to its clients in terms of surface recovery, involving activities such as:

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• Technical inspection, diagnosis and surface repair design.

• Welding recovery.

• Penetrant inspection.

• Mechanical polishing.

• Electropolishing.

• Ultrasound inspection.

• Roughness inspection.

• Chemical cleaning to remove free iron, complex oxides.

• Chemical passivation to recondition the passive film and obtain maximum resistance to contamination and surface corrosion.

• Certification of passivation using CPP/ASME BPE technique with PassivityScan®.

 

Surfaces with severe corrosion, such as the bottom plate of storage tanks or the wall of preparation tanks, require welding recovery. However, it is not just any solder that can be deposited because, in this way, the places of recovery by welding become preferential points of contamination and corrosion due to metallurgical defects. ACW Engenharia uses laser TIG or pulsed TIG welding machines to apply an adequate thermal input and reduced chemical partitioning of the deposited metal, combined with the use of welding consumables with enrichment of certain alloying elements, such as chromium, molybdenum, nickel, among others. Advanced metallurgical knowledge makes ACW Engenharia the best option for recovering stainless steel surfaces.

 

Stainless steel surfaces with contaminants, rouge or biofilm can be recovered through chemical treatments, mechanical polishing or electropolishing. ACW Engenharia offers a complete state-of-the-art scope so that used equipment with surface problems becomes “like new” equipment with its surface properly meeting a sanitary standard.

 

We recover equipment surfaces such as:

• Tanks.

• fermenters.

• Heat exchangers and pressure vessels.

• Autoclaves.

• Streamers.

• Medical technology devices.

 

At the end of the project, ACW Engenharia provides complete documentation certifying the sanitary quality of the recovered surface in accordance with GMP and ASME BPE.