Valve Standard Reference
API 599
AmericanMetal Plug Valves — Flanged, Threaded and Welding End
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.
Overview — API 599
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.
Scope
Covers metal plug valves (cylindrical and conical tapered plug designs) with flanged, threaded, or butt-welding end connections, Class 150–600. Applies to both lubricated and non-lubricated plug valves in NPS ½" to NPS 24" sizes.
Applicable Valve Types
Plug Valves — lubricated (WCB, WC6)
Plug Valves — non-lubricated (CF8M, CF3M)
Eccentric plug valves
Applicable Pressure Classes
Key Requirements — API 599
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 — API 599
Shell hydrostatic test: 1.5× rated pressure, zero external leakage
Seat leakage test: 1.1× rated pressure per API 598 Class IV or VI
Documentation Required for API 599 Compliance
Material test certificates (EN 10204 3.1 or 3.2) for all pressure-containing parts
Hydrostatic shell test report
Seat leakage test certificate
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