Pickling and passivation is a chemical reaction to remove rust from the stainless steel’s surface.
As for pickling and passivation of stainless steel, it is to remove oil, rust, oxide scale, welding spot and other dirt on the surface. After the treatment, surface appears uniform in its color, silver white, which greatly improves the corrosion resistance of stainless steel tube.
This method is simple and cost-efficient. At the same time, high efficiency corrosion inhibitor and fog inhibitor are added to prevent the material from corrosion and hydrogen embrittlement, as well as acid fog. Based on the different material and the oxide skin, it can be operated with original solution or complying with ratio of 1:1 to 4 water after dilution. Austenitic stainless steel with low content of ferrite, martensite and nickel (like 420, 430, 200, 201, 202, 300, 301, etc.) are used after dilution. Austenitic stainless steel, with higher content of nickel like 304, 321, 316, 316L, is soaked in the original solution, at normal temperature or heating to 50 ~ 60 degrees, immersed by 3-20 minutes or longer, according to specific conditions. Then the dirt is on the surface is completely removed, the stainless pipe appears to be silvery white, and the passivation film is formed uniformly. After the processing is completed, the pipe is rinsed off with clear water, or flush with alkaline and whitewash further.