Valve Standard Reference
API 623
AmericanSteel Globe Valves — Flanged and Butt-Welding Ends, Bolted Bonnet
API 623 is the API specification for steel globe valves with flanged and butt-welding ends and bolted bonnets, intended for petroleum, petrochemical, and allied industries.
Overview — API 623
API 623 is the API specification for steel globe valves with flanged and butt-welding ends and bolted bonnets, intended for petroleum, petrochemical, and allied industries. Published as a companion standard to API 600 (gate valves) and API 602 (smaller steel valves), API 623 establishes design, material, dimensional, testing, inspection, and marking requirements for globe valves that provide precise throttling and flow control in process plant service. Globe valves specified to API 623 are the standard choice for control valve bypass lines, let-down stations, and any service requiring precise flow regulation under sustained differential pressure.
Scope
Covers carbon steel, alloy steel, and stainless steel globe valves with flanged ends (per ASME B16.5) or butt-welding ends (per ASME B16.25), bolted bonnet construction, in sizes NPS ½" through NPS 24", pressure classes 150 through 2500 (ASME Class). Intended for petroleum refining, petrochemical, chemical, and gas processing plants.
Applicable Valve Types
Globe Valves — straight pattern (flanged and butt-welding ends)
Globe Valves — angle pattern
Globe Valves — Y-pattern (oblique body)
Applicable Pressure Classes
Key Requirements — API 623
Body and bonnet wall thickness must meet ASME B16.34 minimum requirements for rated pressure class
Trim (disc and seat ring) hardness: hard-faced Stellite 6 or 21 for erosive, cavitating, or high ΔP services
Bolted bonnet: ASME B16.5 flange standard for bonnet joint; ring-joint (RTJ) optional for Class 600+
Rising stem (OS&Y — outside screw and yoke) design standard for visibility of valve position
Backseat provision for stem packing replacement under pressure (when specified)
Anti-rotation pin between disc and stem to prevent disc spin in service
Fugitive emission packing systems per ISO 15848-1 available as option
Marking: ASME class, material designation, size, body material heat code on body casting
Testing Requirements — API 623
Shell test: 1.5× rated pressure, 15 minutes, zero leakage through body or bonnet joint
Seat leakage test: 1.1× rated pressure per API 598 acceptance classes
Backseat test when backseat is provided: 1.1× rated pressure, zero leakage
Documentation Required for API 623 Compliance
API 623 compliance certificate
Shell and seat test certificate with pressure, duration, and leakage data
Material Test Reports (MTR) per EN 10204 3.1
Dimensional report for body and end flanges
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