API SPEC 6D-2021 管道阀门规范 25版 Specification for Valves

Introduction
Changes from the 24th to the 25th Edition
This specification is the result of updating the requirements from API Specification 6D, 24th Edition, includingAddendum 1 and Addendum 2. The revision of API 6D, 25th Edition, was developed based on input from the AP¹6DTask Group technical experts globally. The technical revisions have been made to accommodate the needs ofindustry and address many interpretations to move this specification to a higher level of service to the petroleum andnatural gas industry. Highlights of some of the significant changes between the 24th edition and 25th edition, include:
- changing the title of the specification;
一reorganizing the specification requirements in an order more aligned with the manufacturing process;一the addition of axial valves to the types of valves covered by this specification;— the removal of Class 400 as a standard pressure class;
一requiring conformance to AP¹ 6DX for valves supplied with actuators;一identifying allowable adjustments for subsize impact specimens;一identifying minimum heat treatment requirements;一identifying minimum bolting requirements;一revising marking requirements;
— providing updated design validation guidance;
一addition of requirements for repair and remanufacture of valves from API 6DR in new AnnexA;— collecting all purchaser-specified requirements into annexes(Annex K and Annex L);
— combining QSL requirements from the 24th edition (Annexes l, J and L into one annex [Annex l]);— adding guidance through-out the document reference to API 20 series specifications and standards.
Units of Measurement
In this standard, data are expressed in both U.S. customary (USC) and metric (SI) units.
Rounding
Except as otherwise required by this specification, to determine conformance with the specified requirements,observed or calculated values are rounded to the nearest unit in the last right-hand place of figures used inexpressing the limiting value, in conformance with the rounding method of ASTM E29 or ISO 80000-1, Annex B,Rule A.
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