API Spec 6 Specification for Pipeline Valves (2002), Includes Annex F, March 2005 This International Standard specifies requirements and gives recommendations for the design, manufacturing, testing and documentation of ball, check, gate and plug valves for application in pipeline systems meeting the requirements of ISO 13623 for the petroleum and natural gas industries.Valves for pressure ratings exceeding PN 420. Standard provides guidelines to assist the purchaser with valve type selection and specification of specific requirements when ordering valves.