Discussion on chloride ion material selection for circulating water medium

Thread Content

Today I searched the forum for posts on the keyword "Circulating Water Chloride Ion Corrosion Material Selection". I browsed it briefly and got some thoughts for your reference. 1. The presence of chloride ions does not mean that stainless steel is inappropriate. It should be understood here that the corrosion mechanism of chloride ions. Most of the available literature states that chloride ions will cause intergranular corrosion of austenitic stainless steel. There are usually three types of stainless steel: Austenite, martensite, ferrite, and duplex steel. 2. GB50050 has a special explanation on the selection of chloride ions. Here are excerpts from it:: “Chloride ions have an impact on the corrosion of stainless steel, but it is not the only factor. ”It should be important to understand here that the corrosion of chloride ions is significantly related to temperature. That is to say, if the concentration is not high, within 700ppm and below 70℃, I think stainless steel and CS are both OK. Even SS will be better and CS will be more economical. 3. The causes of corrosion and the mechanism of corrosion are intricate and involve many aspects. Material defects, corrosive media, temperature, pressure, etc. all affect the corrosion rate. Therefore, specific situations should be analyzed on a case-by-case basis. 4. Of course, for non-circulating water systems, high temperature and high concentration CL-corrosion should be treated separately. Chloride ions are sensitive to austenite. So in many cases it is possible to use CS directly. 5. According to the field experience I know, 304, 316, 304L, and 316L are all acceptable for chloride ions within 700PPM at 70°C. Of course, the one with L should be better. If you are not sure, it is also feasible to use martensitic Cr steel. 6. I hope to inspire my colleagues. However, specific issues should be analyzed in detail, supported by engineering experience, and supported by standards and specifications, so that the design is feasible. Welcome to discuss.