This Specification specifies requirements and provides recommendations for the design, manufacturing, testing and documentation of ball, check, gate and plug valves for application in pipeline systems meeting ISO 13623 or similar requirements for the petroleum and natural gas industries.This Specification is not applicable to subsea pipeline valves, as they are covered by a separate Specification (API Spec 6DSS).This Specification is not for application to valves for pressure ratings exceeding PN 420 (Class 2 500)This edition of API Specification 6D is the identical national adoption of ISO 14313:2007, Petroleum and natural gas industries-Pipeline transportation systemes-Pipeline valves. This specification contains the API Monogram Annex as part of the U.S. national adoption.