This standard identifies requirements for heat treatment supplier qualification, processing, identification and traceability, and documentation of heat treatment services for use in the petroleum and natural gas industries when referenced by an applicable equipment specification. The requirements of this standard apply to batch heat treatment operations that establish or affect the final mechanical properties and include stress relief operations. This standard applies to carbon steel, low-alloy steel, stainless steel, and nickel-base alloys. Case hardening, induction hardening, and flame hardening are not covered by this standard. This standard establishes the requirements for three heat treatment specification levels (HSLs). These HSL designations define different levels of heat treatment technical, quality, and qualification requirements.