The five standards at a glance
| Standard | Type | Covers | Typical service | Testing |
|---|---|---|---|---|
| API 598 | Test standard | Inspection, supplementary examination and pressure testing of gate, globe, plug, ball, check and butterfly valves | Valves where the order calls it up | Is the test standard |
| API 600 | Product standard | Steel gate valves with bolted bonnets | Petroleum refinery and related applications | API 598 shell and seat tests, per common comparisons |
| API 608 | Product standard | Metal ball valves, floating and trunnion, with flanged, butt-welding, socket-welding or threaded ends | Petroleum, petrochemical and industrial applications | Shell and seat tests; check the edition and the spec |
| API 6A | Product standard | Wellhead and Christmas tree equipment, including valves | Upstream drilling and production | Its own tests, linked to its specification levels |
| API 6D | Product standard | Axial, ball, check, gate and plug valves | Pipelines and wider oil and gas service | Its own factory acceptance tests |
API 598: valve inspection and testing
API 598 covers inspection, supplementary examination and pressure testing of gate, globe, plug, ball, check and butterfly valves. It describes a shell test of the body, a backseat test where the valve has one, and low- and high-pressure closure (seat) tests, with allowable seat leakage set in a table that depends on valve type, size and seat design (projectmaterials; WhatIsPiping). Published summaries disagree on some pressures and durations, so take figures from the current edition, not from a blog.
What to flag: a tender that asks for API 598 testing on a valve built to API 6D or API 6A, which have their own tests; a gas seat test where you offer liquid only; and any leakage criterion that is tighter than the standard's.
API 600: bolted-bonnet steel gate valves
API 600 covers a heavy-duty series of bolted-bonnet steel gate valves for petroleum refinery and related applications (GlobalSpec). It sets its own minimum wall thicknesses and uses the ASME B16.34 material groups for body materials (projectmaterials).
What to flag: trim, wall-thickness basis, bonnet type, and packing and stem-seal requirements. Trade sources note that API 624 fugitive-emission testing has been or may be written into rising-stem valve standards such as API 600 (Chesterton), and many specs ask for API 624 or ISO 15848-1 separately.
API 608: metal ball valves
API 608 covers metal ball valves for petroleum, petrochemical and industrial applications, in floating (seat-supported) and trunnion designs. The 12th edition covers flanged and butt-welding ends from NPS 1/2 to NPS 24 and socket-welding and threaded ends from NPS 1/4 to NPS 2, and excludes trunnion valves with double-piston-effect seats (Standard Norge). It sits beside API 6D: a ball valve for a process facility may be called up under API 608, and one for a pipeline under API 6D (projectmaterials).
What to flag: the size, end and class range the edition covers compared with what you offer, a double-piston-effect seat request on a trunnion valve, seat material and its temperature limit, the fire-test requirement, and any stem features the spec names.
API 6A: wellhead and tree equipment
API 6A covers wellhead and Christmas tree equipment, including the valves on a tree. Its ratings are working pressures from 2,000 to 20,000 psi rather than ASME classes, and the buyer selects a product specification level (PSL 1 to 4), a performance requirement level (PR1 or PR2), a temperature class (letter codes K to V) and a material class (AA to HH) (Stream-Flo; projectmaterials).
What to flag: every one of those selections. A tender that asks for one PSL or material class where your standard product is qualified to another is a deviation, and a missing selection is a TQ.
What is the difference between API 6D and API 600?
API 6D is a specification for axial, ball, check, gate and plug valves with its own factory acceptance tests. API 600 covers only bolted-bonnet steel gate valves for refinery and related service, commonly tested to API 598. See the API 6D page for detail.
| Question | API 6D | API 600 |
|---|---|---|
| Which valves? | Axial, ball, check, gate, plug | Bolted-bonnet steel gate valves |
| Where used? | Pipelines and wider oil and gas service | Petroleum refinery and related applications |
| Test standard? | Its own factory acceptance tests | Commonly API 598 |
| Typical tender trap | Edition and addenda, seat arrangement, quality specification level | Trim, packing and fugitive-emission test |
How to use these standards in your offer
- Name the product standard and edition you build to on the datasheet.
- Name the test standard separately, and say if it differs from the one the tender asks for.
- List added owner and project requirements as separate rows; they often go beyond the API standard.
- Declare every gap in your technical deviation list, with a cost of withdrawal.
Related: ISO 15848-1 fugitive emissions, EN 10204 3.1 vs 3.2, the datasheet vs specification checklist and the free templates. OdysseyGPT lists each standard and requirement a tender calls up, with clause and page, for an engineer to check; see OdysseyGPT for manufacturing.