Sandvik provides chemical products for improving the surface finish and corrosion resistance of welds. These include root flux for root protection during welding, pickling paste for post weld treatment and neutralization paste for neutralizing pickling residues to pH value 7-10, facilitating rapid precipitation of metallics.
Root flux is used for weld root protection during welding of tube joints and other cases when it is impractical or accessibility restricts the use of shielding gases. When shielding gas cannot be used root flux minimizes the risk of porosity, weld oxides and burn-through. The root flux is brushed on approximately 20 mm on each side of the joint. During welding the flux is activated and creates a thin layer of protective slag. When the tubes are in operation, the slag will be washed off by the process fluid.
The optimal corrosion resistance in stainless steel weld metals and heat affected zones (HAZ) is achieved when the weld oxide and chromium depleted region are removed. This is achieved by brushing, grinding or pickling. Pickling gives the best corrosion resistance.
Pitting resistance potential
The pickling paste is thixotropic, which means it is easy to apply in different welding positions and does not drip or splash.
After pickling, aggressive acid residues always remain on the weld. These residues are easily neutralized with Sandvik Neutralization paste. Corrosion at a later date can thereby be avoided and the best possible environmental care achieved. The neutralization paste is thixotropic, which means it is easy to apply in various welding positions and it can afterwards be flushed off safely with water.