Leakage due to alkali corrosion perforation of thin-walled stainless steel pipe

The tap water mains system was improperly managed to introduce sewage, which contained high levels of the alkali metals potassium and calcium, and ultimately, the thin-walled stainless steel pipes used for the connections were perforated by alkali corrosion, leading to leakage. Further macroscopic observations revealed that the corrosion perforations were all located in the base metal near the weld. Visual inspection, chemical composition analysis, tensile test analysis, energy dispersive spectroscopy (EDS), and electrochemical corrosion potential experiments were used to investigate the cause of the pipe perforations. Identify risk points leading to pipe failure through experimental studies and propose appropriate preventive measures. The study found that the elements "C," "O," and "K" are distributed along the corrosion area, and "P" and "Ca" are concentrated in the most corroded areas. In the alkaline solution, the average corrosion potential in the weld area is -471.5mV, and the average corrosion potential in the base metal area near the weld is -588.6mV, and the pipe has a tendency to corrode electrochemically in sewage containing low melting-point eutectic substances and metal impurities. Eventually, alkali and electrochemical corrosion together lead to corrosion perforation of the pipe. On this basis, suggestions and countermeasures for the failure of the thin-walled stainless steel pipe were put forward.