Abstract: Cracking and leakage of stainless steel process gas pipe at the entrance of a chemical enterprise container occurred. The causes of gas pipe leakage were analyzed by means of macroscopic observation, penetrant test, chemical composition analysis, mechanical property test, metallographic examination and fracture analysis. The results show that the chemical composition and mechanical properties of the leak pipe material met the requirements of the standard. The cracking property of the pipe section was chlorine-induced stress corrosion cracking. The poor weld formation and incomplete penetration of the root caused the chloride in the process medium to accumulate at the welding defects, which increased the sensitivity of stress corrosion cracking. Finally, the improvement suggestions were put forward to reduce the possibility of chlorine-induced stress corrosion cracking.