Description / Abstract: API SPEC 6D, 25th Edition, December 2021 - Specification for Valves This specification defines the requirements for the design, manufacturing, materials, welding, quality control, assembly, testing, marking, documentation, and process controls of axial, ball, check, gate, and plug valves for application in the petroleum and natural gas industries. This specification applies to ASME Class 150, 300, 600, 900, 1500, and 2500. NOTE ASME Class 400 has been removed from this specification. API 6DR for repair and remanufacture of valves has been withdrawn and has been replaced by Annex A. Annexes A, B, D, E, F, J, and L are informative and contain optional requirements used in this specification. Annexes C, G, H, I, and K are normative and are mandatory in the use of this specification. Information marked “NOTE” are not requirements but are provided for guidance in understanding or clarifying the associated requirement.