API 599 Plug Valves
What API 599 requires for plug valves — applicability, key and testing requirements, the alternative standards, and compliant supply with full certification.
What does API 599 require for plug valves?
API 599 (Metal Plug Valves - Flanged, Threaded and Welding End, American Petroleum Institute (API)) sets the design, material and testing requirements for plug valves in its scope. API 599 specifies requirements for metal plug valves with flanged, threaded, and welding end connections, in sizes NPS ½" to NPS 24" for Class 150 to 600. It covers both lubricated and non-lubricated designs in carbon steel, stainless steel, and other alloy materials for general chemical, oil & gas, and refinery process service.
Applicable Pressure Classes
Key Requirements
- Pressure-temperature ratings per ASME B16.34 for the applicable pressure class and body material
- Seat leakage testing per API 598 - Class IV or Class VI leakage rates as specified
- Shell hydrostatic test at 1.5× rated pressure, minimum hold time per API 598
- Stem sealing: live-loaded packing or equivalent to prevent fugitive emissions
- Fire-safe design per API 607 when specified for hydrocarbon service
- Minimum wall thickness per pressure class and temperature requirements
- Material qualification per ASTM specifications for pressure-containing parts
Testing Requirements
- Shell hydrostatic test: 1.5× rated pressure, zero external leakage
- Seat leakage test: 1.1× rated pressure per API 598 Class IV or VI
Alternative Standards for Plug Valves
Other standards that also govern plug valves — useful for spec cross-acceptance.
Connected Engineering
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