The API standard for plug valves is mainly API 599-2007 "Metal Plug Valves with Flange Ends, Threaded Ends and Welded Ends", and its core specifications are as follows:
1. Scope of application
Connection form: Covers three connection methods: flange end, threaded end, and butt welding end.
Valve body material: Applicable to steel and alloy plug valves (including carbon steel, stainless steel, etc.), as well as flange end ductile iron plug valves.
Diameter and pressure: Nominal size DN25~DN600 (NPS 1~24), pressure level covers CL150~CL2500 (corresponding to ASME B16.34 standard).
2. Key technical requirements
Sealing system classification: Oil-sealed plug valve: Rely on grease to fill the sealing cavity to reduce friction; Non-lubricated plug valve: Use polymer bushings such as PTFE or metal hard seals.
Structural design:
It must meet the bidirectional sealing capability, and the port form is limited to bidirectional coaxial port (not three-way or multi-channel);
It is allowed to configure internal valve body/plug lining (such as PFA lining) or hardening treatment (surface welding of cemented carbide) to improve corrosion resistance.
Pressure performance:
The valve body pressure-temperature rating must comply with the ASME B16.34 standard, and the welding end valve must specify the groove size.
3. Procurement and inspection requirements
Buyer's responsibilities: The order must specify the valve size, pound class, seal type (oil seal/non-lubricated), end connection details (such as flange sealing surface type) and actuator configuration.
Test standards:
The sealing and strength tests follow API 598 "Valve Inspection and Testing", including shell tests, low-pressure/high-pressure sealing tests;
The fire protection requirements refer to API 607 (applicable to non-metallic soft-seal plug valves) or API 6FA (metal-sealed valves).
4. Related standard system
Interface standard: Flange size is based on ASME B16.5/B16.47, butt welding end complies with ASME B16.25; Material specification: Pressure-bearing parts materials must meet the requirements of ASME II, and non-standard alloys must provide corrosion resistance data.
Note: API 599 is the core procurement specification for metal plug valves in the petroleum, chemical and natural gas industries, and together with ISO 14313 (general requirements for pipeline valves) and ASME B16.34, it constitutes a complete technical system.
