API 6A Plug Valves
What API 6A requires for plug valves — applicability, key and testing requirements, the alternative standards, and compliant supply with full certification.
What does API 6A require for plug valves?
API 6A (Specification for Wellhead and Christmas Tree Equipment, American Petroleum Institute (API)) sets the design, material and testing requirements for plug valves in its scope. API 6A is the fundamental specification for wellhead and Christmas tree equipment used in oil and gas well drilling and production. It covers all equipment installed at the top of a well casing - including casing heads, tubing heads, Christmas trees, choke valves, gate valves, and actuators - that must contain wellbore pressures that can reach 20,000 psi. API 6A valves are subjected to far more rigorous qualification testing than standard process plant valves and must be tested at the rated working pressure of the equipment, not a fraction of it. The standard is mandatory for virtually all oil and gas wellhead equipment worldwide.
Applicable Pressure Classes
Key Requirements
- Product Specification Level (PSL): 1, 2, 3, 3G, or 4 - each with escalating quality, testing, and documentation requirements
- Working pressure classes: 2000, 3000, 5000, 10000, 15000, and 20000 psi
- Temperature classes: K (−60 to 82°C), L (−46 to 82°C), P (−29 to 82°C), R (−18 to 121°C), S (0 to 60°C), T (−18 to 82°C), U (0 to 121°C), V (2 to 180°C)
- Material classes: AA (general service), BB (H₂S partial, CO₂), CC (H₂S full, NACE), DD, EE, FF, HH per NACE MR0175
- All load-bearing and pressure-containing parts must meet minimum yield strength per temperature class
- Traceability: full heat/lot traceability required for PSL 2, 3, 3G, 4
- Factory acceptance test (FAT): hydrostatic body test + seat test at rated WP for all PSL levels
- Third-party certification mandatory for PSL 3, 3G, 4
Testing Requirements
- Hydrostatic body (shell) test at 1.5× rated working pressure
- Seat (gate/seat interface) test at rated working pressure, both upstream and downstream seats
- Low-pressure gas seat test at 100–200 psi for PSL 3G/4
- Functional test: full open-to-close-to-open cycle under rated pressure
- Extended cyclic pressure test for PSL 3G and 4 qualification
Alternative Standards for Plug Valves
Other standards that also govern plug valves — useful for spec cross-acceptance.
Connected Engineering
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