Weld Cleaning & Passivation

Weld cleaning and passivation equipment removes the heat tint left beside stainless steel welds and helps the surface regain its corrosion resistance. Seven Star LLC lists four electrochemical weld cleaning machines from Cougartron for buyers in Oman, from an entry-level unit and a precision TIG weld cleaner to heavy-duty machines. The range is growing, and other models, brushes and cleaning fluids can be sourced on request.

How electrochemical weld cleaning works

The machine passes a low-voltage current through a conductive carbon fiber brush wetted with an electrolyte fluid. Where the brush touches the weld, the discolored oxide layer is dissolved in seconds, without the abrasion of grinding and without leaving pickling paste on the metal. The surface is then neutralized and rinsed. Stainless steel resists corrosion through a thin chromium oxide film, and welding heat damages that film and the layer beneath it. Removing the tinted layer lets a sound passive film form again. ASTM A380 and ASTM A967 are the documents most often cited for cleaning and passivation of stainless steel.

Choosing a weld cleaning machine

Output power sets the working speed. Light units suit thin TIG welds on sheet, tube and handrail. Heavier units are meant for long seams and for MIG welds, which carry more oxide and spatter residue. Tank, vessel and pipe spool fabricators serving food, pharmaceutical and desalination projects in the GCC are typical users. For a quotation, send the material grade, weld type, approximate weld length per day, the surface finish required and the supply voltage.