Prevention of External Chloride Stress Corrosion Cracking of Austenitic Stainless Steel with a Thermal Sprayed Aluminum Coating

External chloride stress corrosion cracking (Cl-ESCC) of insulated austenitic stainless steels such as, for example, SS 304 and SS 316 can occur when chloride-containing water is present underneath the insulation, the external metal skin temperature exceeds about 50 °C and there is no surface protection or when the paint protection is damaged. A thermal sprayed aluminum (TSA) coating is expected not only to provide a robust barrier that prevents corrosive water from reaching the stainless steel metal surface but also to provide cathodic protection when the TSA coating is damaged. Electrochemical tests and slow strain rate tests were performed to show the protective ability of a thermal sprayed aluminum coating to prevent chloride stress corrosion cracking of SS 304L in aqueous chloride solutions. To compare the application of a TSA coating with other methods to mitigate Cl-ESCC, this paper also discusses alternative mitigation methods.