What is the API 6D standard for valves?
API 6D sets requirements for the design, manufacture and testing of axial, ball, check, gate and plug valves. Its 25th edition, published in November 2021, changed the title from "Specification for Pipeline and Piping Valves" to "Specification for Valves", reflecting use across the oil and gas industry rather than only in pipelines (Valve World Americas). Manufacturers licensed under API's Monogram Program may apply the API monogram to products made to the specification (API).
| Area | What it covers in outline |
|---|---|
| Valve types | Axial, ball, check, gate and plug valves |
| Design and manufacture | Design requirements and how the valve is built; an informative annex gives one method of design validation |
| Testing | Factory acceptance testing, including high- and low-pressure seat tests, with added tests at higher quality specification levels (QSL) |
| Marking and documents | Valve marking and the documents supplied with the valve |
What is the latest version of API 6D?
The 25th edition (November 2021) is the base edition the US pipeline regulator references: a July 2025 PHMSA notice lists it with three errata (December 2021, April 2022, October 2023) and three addenda (April 2023, September 2024, March 2025) (Federal Register, July 2025). Check the API publications site for anything issued since, and make sure the edition and addenda in the tender match those you design and test to. If the tender says "latest edition", state the edition in your offer as a clarification.
What is the difference between API 6D and API 600?
API 6D covers several valve types for pipeline and wider oil and gas service. API 600 covers steel gate valves with bolted bonnets for petroleum refinery and related applications (GlobalSpec). A gate valve could fall under either, depending on the service and the specification the buyer calls up. The API valve standards hub compares 6D, 600, 598, 608 and 6A side by side.
| API 6D | API 600 | |
|---|---|---|
| Valve types | Axial, ball, check, gate, plug | Steel gate valves |
| Typical service | Pipelines and wider oil and gas service | Petroleum refinery and related applications |
| Testing | Its own factory acceptance tests | API 598 shell and seat tests, per a common comparison (projectmaterials) |
Where API 6D sits with other requirements
A tender seldom asks for API 6D alone. It usually layers a project specification and an owner standard on top, plus other standards for fire testing, fugitive emissions, sour service and material certificates. When these disagree, the order of precedence decides which wins. See governing-document precedence, ISO 15848-1, EN 10204 3.1 vs 3.2 and the Gulf owner-spec checklist.
Missing API 6D paperwork can sink a bid on its own. In OGDCL evaluations, a missing API 6D certificate is a typical rejection ground (OGDCL clarification).
What to check in a vendor datasheet against API 6D
Use this table when you check your own datasheet, or a sub-supplier's, against a tender that calls up API 6D. Any "no" becomes a row in your technical deviation list.
| Datasheet item | Check against | Typical deviation source |
|---|---|---|
| Edition and addenda | Edition and addenda named in the tender | Datasheet cites an older edition, misses an addendum or says "latest" |
| Valve type and design | Requisition and spec | Floating ball offered where trunnion is specified, or the reverse |
| Size, class and bore | Datasheet and piping class | Reduced bore offered where full bore is needed for pigging |
| End connections | Piping class | Flange facing or weld-end bore does not match the pipe |
| Body, closure and trim materials | Spec, piping class, sour-service requirement | Cast offered for forged; trim hardness not stated |
| Impact testing | Minimum design temperature | Impact test temperature missing or too warm |
| Seat design and cavity relief | Seat function the spec asks for | Seat arrangement differs from the function required |
| Pressure tests and QSL | API 6D factory acceptance tests, the quality specification level and any supplementary tests in the spec | Higher QSL or extra tests asked for but not priced |
| Fire test | Spec | Different fire-test standard cited |
| Fugitive emissions | Spec | No ISO 15848-1 or API qualification offered |
| Operator | Spec and datasheet | Gear or actuator sizing basis not stated |
| Marking and monogram | Spec | API monogram required but not offered |
| Documents and certificates | VDRL, ITP | 3.1 offered where 3.2 is required; missing API 6D certificate |
For a longer, equipment-neutral list, use the 25-point datasheet vs specification checklist and the free templates. OdysseyGPT drafts these rows from the tender package with the clause and page for each, for an engineer to check; see OdysseyGPT for manufacturing.