Revised in 2005. Defines material requirements for resistance to sulfide stress cracking (SSC) in sour refinery process environments (i.e., environments that contain wet hydrogen sulfide [H2S]). The term "wet H2S cracking" as used in the refining industry covers a range of damage mechanisms that can occur due to the effects of hydrogen charging in wet H2S refinery or gas plant process environments. One of the types of material damage that can occur as a result of hydrogen charging is sulfide stress cracking (SSC) of hard weldments and microstructures, which is addressed by this standard. This standard is intented to be utilized by refineries, equipment manufacturers, engineering contractors, and construction contractors.