Abstract: RIC manual valves and seal assemblies made of austenitic stainless steel were wrongly degreased with tetrachloroethylene by the manufacturer. Chloride ions（Cl^-） were produced during the pyrolysis of tetrachloroethylene,leading to the risk of stress corrosion cracking（SCC） due to the remaining Cl^-. The research shows that the Cr-Ni austenitic stainless steel becomes more sensitive to the stress corrosion cracking as the Cl^-content increases. Increasing temperature and oxygen（O） content can accelerate the SCC of austenitic stainless steel caused by Cl^-. After the analysis of the remaining Cl^- content in the manual valves and seal assemblies, operating temperature and oxygen content in the coolant, it is considered that the remaining Cl^- will not cause SCC during service of manual valves and seal assemblies. In addition, the pyrolysis of tetrachloroethylene under vacuum and abrasive blasting of surfaces can degrease Cl^- observably.