Intended to be a primary source of information on cracking in wet H₂S petroleum refinery environments. Provides guidelines on detection, repair, and mitigation of cracking of existing carbon steel refinery pressure vessels, including columns, heat exchangers, drums, reboilers, separators, and more. In this standard, "wet H₂S service" is defined as refinery process environments in which the concentration of H₂S is 50 ppmw or greater in the aqueous phase. Thirteen tables show the frequency and severity of cracking as reported in a survey conducted on the topic. Examples of cracking are shown in photographs.