The chloride ion concentration of the medium and the selection of condenser material
Thread Content
There is a project that requires the design of a condenser, with cooling water flowing on the shell side. The cooling water is reclaimed water from a wastewater treatment plant, with a chloride ion concentration of 340 ppm and a conductivity of 7000. The temporary piping is to be made of 316 stainless steel, while the cylinder body is to be made of carbon steel. I asked several technicians; some said that this chloride ion concentration has little effect on carbon steel, while others said that carbon steel corrodes more severely than stainless steel. I’m asking the experts on this forum for an accurate conclusion – waiting online.
Chloride ion concentration has little effect on carbon steel
In pressure vessels made of austenitic stainless steel, stress corrosion occurs in the presence of chloride solutions. This is because the chloride ions in the solution damage the passivation film on the surface of stainless steel; under tensile stress, cracks appear in the areas where the passivation film has been damaged, which become the anodic regions of corrosion cells. Continuous electrochemical corrosion can ultimately lead to the fracture of the metal. This type of corrosion is not greatly dependent on the concentration of chloride ions; even trace amounts of chloride ions can cause stress corrosion. Therefore, the pressure test limits the chloride ion concentration to below 25 ppm.
For your CI-340PPM, you definitely can’t use 316; use carbon steel instead
This is also related to temperature; the original poster can search on Baidu for information on stainless steel materials that are recommended when chloride ions interact with factors such as temperature and pH.
Stainless steel is not suitable for applications with high chloride ion concentrations； Can carbon steel be used to determine the acidity or alkalinity of a solution, rather than relying on chloride ion concentration?
Chloride ion concentration has a significant impact on austenitic stainless steel, but seems to have little effect on carbon steel.
For lower temperatures, below 50°C, I’ve checked and it should work