Reference Guide June 28, 2026 12 min read

Industrial Valve Standards: API, ASME, BS & EN — Complete Reference Guide

Every valve purchase order references at least one design standard, one testing standard, and one dimensional standard. Misunderstanding which standard applies can lead to incorrect valve procurement. This guide maps the major valve standards to valve types and explains when each standard applies.

Valve Standards by Type

Valve Type	Design Standard	F-to-F Dimensions	Testing	Flanges
Cast Gate Valve	API 600	ASME B16.10	API 598	ASME B16.5
Cast Globe Valve	BS 1873	ASME B16.10	API 598	ASME B16.5
Forged Gate/Globe/Check	API 602	ASME B16.10	API 598	ASME B16.5
Pipeline Ball Valve	API 6D	API 6D	API 6D	ASME B16.5/B16.47
Metallic Ball Valve	API 608	ASME B16.10	API 598	ASME B16.5
Butterfly Valve	API 609	API 609 / MSS SP-67	API 598	ASME B16.5
Check Valve (Cast)	BS 1868 (swing), API 594 (dual plate)	ASME B16.10	API 598	ASME B16.5
Plug Valve	API 599	ASME B16.10	API 598	ASME B16.5

API 600 — Steel Gate Valves

API 600 is the design standard for flanged, butt-welding, and other cast steel gate valves with bolted bonnets. It covers sizes NPS 1 and larger, pressure classes 150 through 2500. API 600 specifies design requirements for body wall thickness, bonnet, yoke, stem, packing, wedge/disc, and seat rings.

Key requirements: OS&Y (outside screw and yoke) rising stem, bolted bonnet with body-bonnet gasket, renewable seat rings, backseat feature, and marking per MSS SP-25.

API 602 — Forged Steel Gate, Globe, and Check Valves

API 602 covers compact forged steel valves in sizes NPS 4 and smaller. These are the standard small-bore valves for instrument lines, bypass piping, drains, and vents in process plants.

Key requirements: Forged body (A105, F11, F22, F304, F316), threaded/socket weld/flanged ends, bolted or welded bonnet, and pressure ratings up to Class 1500 (or API 10000 for special trim).

API 6D — Pipeline and Piping Valves

API 6D covers pipeline valves: ball, gate, plug, and check valves used in pipelines and pigging operations. It is the primary standard for midstream (pipeline) valve procurement. API 6D valves undergo more rigorous testing than API 598, including extended seat tests, cavity relief testing, and optional Appendix F enhanced testing.

ASME B16.34 — The Universal Standard

ASME B16.34 is not a valve design standard — it is the universal standard for pressure-temperature ratings, dimensional requirements, and minimum wall thicknesses for flanged, threaded, and welded valves. All API valve standards reference ASME B16.34 for P-T ratings. When a valve is marked "ASME B16.34 Class 300", it means the body wall thickness and P-T rating comply with this standard.

European vs American Standards

Valve Type	American (API/ASME)	British (BS)	European (EN)
Gate Valve	API 600	BS 1414	EN 12516
Globe Valve	BS 1873	BS 1873	EN 12516
Check Valve	BS 1868	BS 1868 / BS 5153	EN 12516
Butterfly Valve	API 609	BS 5155	EN 593
Ball Valve	API 608 / API 6D	BS 5351	EN 12516
Pressure Rating	ASME B16.34	BS 5351/BS 6755	EN 12516-1/2
Flanges	ASME B16.5 / B16.47	BS 1560 / BS 10	EN 1092-1

Which Standards for Middle East Projects?

Most Middle East oil & gas, petrochemical, and power projects use American (API/ASME) standards. Key project specifications to check:

Saudi Aramco: SAES-L-008 (piping), SAES-L-108 (valves), SAMSS material system specifications — all reference API/ASME standards
ADNOC: API/ASME with ADNOC-specific amendments
QatarEnergy: API/ASME with QP specifications
Kuwait (KOC/KNPC): API/ASME standards
Water/desalination: May use BS/EN standards for butterfly and gate valves — always check the project specification

Frequently Asked Questions

What is the difference between API 600 and ASME B16.34?

API 600 is a valve design standard specific to steel gate valves — it specifies construction details like bonnet type, stem design, seat rings, and packing. ASME B16.34 is a universal standard that provides pressure-temperature ratings and minimum wall thicknesses for all flanged/threaded/welded valves regardless of type. API 600 references ASME B16.34 for P-T ratings. In practice, a gate valve is designed to API 600 and rated per ASME B16.34.

Is API 6D better than API 608 for ball valves?

API 6D and API 608 serve different purposes. API 6D covers pipeline ball valves — it includes more rigorous testing (extended seat tests, cavity relief, optional Appendix F) and requirements specific to pipeline service (piggability, double block and bleed). API 608 covers general-purpose metallic ball valves for process plant service. For pipeline applications, API 6D is mandatory. For in-plant process isolation, API 608 or API 6D are both acceptable.

Do I need to specify separate standards for testing and design?

Yes. The design standard (API 600, API 6D, etc.) covers the valve construction. The testing standard (API 598 for most valves, API 6D for pipeline valves) covers factory testing procedures and acceptance criteria. The dimensional standard (ASME B16.10) covers face-to-face and end-to-end dimensions. The flange standard (ASME B16.5) covers flange dimensions and bolting. A complete valve specification should reference all applicable standards.

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