Quick Answer
API 602 is the American Petroleum Institute specification for compact steel gate, globe, and check valves for petroleum and natural gas service, in sizes NPS 1/2 through NPS 4. It defines materials, pressure-temperature ratings (per ASME B16.34), end connections, and testing requirements. If you need a small, heavy-duty bolted-bonnet steel valve, API 602 is the standard to specify.
What API 602 Covers
API 602 (Compact Steel Gate Valves — Flanged, Threaded, Welding, and Extended-Body Ends) applies to small bore valves used in refineries, pipelines, and production facilities. It references:
- ASME B16.34 — pressure-temperature ratings
- ASME B16.10 / B16.5 — dimensions and flanges
- API 598 / ISO 5208 — inspection and testing
- ASTM material specs — body, bonnet, and trim materials
Key Requirements
| Requirement | Detail |
|---|---|
| Size range | NPS 1/2 to 4 |
| Valve types | Gate, globe, and check valves |
| End connections | Flanged, threaded, butt-weld, socket-weld |
| Bonnet design | Bolted bonnet standard (welded optional) |
| Testing | Hydrostatic shell and seat tests per API 598 |
| Ratings | Class 150 through Class 800 typical |
API 602 vs. API 600
API 600 covers large bolted-bonnet steel gate valves (NPS 2 and larger, typically Class 150-2500). API 602 covers the compact small-bore range (NPS 1/2-4). The compact design of API 602 valves reduces weight and cost while keeping heavy-duty service capability.
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Common Mistakes
- Assuming API 602 is a certification — it is a specification; conformance is declared by the manufacturer and can be witnessed by third-party inspectors
- Using a general-purpose ball valve where an API 602 gate is required for hydrocarbon block service
- Specifying API 602 without a trim material — API 602 allows several trim classes that must be chosen for the service
- Forgetting to verify the fire-safe design requirement for soft-seated variants
Frequently Asked Questions
What is the difference between API 602 and ASME B16.34?
ASME B16.34 is the general pressure-temperature rating and design standard for all flanged valves. API 602 is a product specification that builds on B16.34 with additional material, testing, and traceability requirements for small steel valves.
What sizes does API 602 cover?
API 602 covers NPS 1/2 through NPS 4 compact steel gate, globe, and check valves.
Is API 602 the same as API 600?
No. API 600 covers larger bolted-bonnet gate valves; API 602 covers the compact small-bore range up to NPS 4.
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Disclaimer: This article is provided for general educational and informational purposes only and does not constitute professional engineering advice. Valve applications vary with pressure, temperature, media, and applicable codes. Always verify specifications against the manufacturer’s data sheet and consult a qualified engineer before selecting, installing, or repairing any valve. Valve Knowledge Hub makes no warranties about the accuracy or completeness of the information on this site and assumes no liability for any use of it.