Reasons for Leakage in Auxiliary Circulation Pipeline of a Desulfurization Tower

The auxiliary circulation pipeline of a desulfurization tower in a certain chemical plant had experienced multiple leaks, resulting in unplanned shutdown of the desulfurization unit for maintenance. The causes of pipeline failure were analyzed through macroscopic examination, penetration testing, metallographic examination, and other methods. The results show that the leakage of the circulating pipeline in the desulfurization tower was caused by pitting perforation and stress corrosion cracking of stainless steel because of chloride solution. Due to the influence of the process, chloride ions as impurity were mixed into the medium, which had strong penetration, could damage the passivation film of 316L stainless steel, causing direct contact between the stainless steel substrate material and the ammonium sulfate solution. The equipment material was corroded by the ammonium sulfate solution, resulting in perforation or cracking in a short period of time.