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The flanged trunnion ball valve is a quarter-turn valve with a fixed ball supported by upper and lower trunnion bearings. This design transfers pipeline pressure loads to the trunnion bearings rather than the seat rings, resulting in lower operating torque compared with floating ball valves at equivalent pressure ratings. The valve is used for on-off and control service in high-pressure pipelines across the oil and gas, petrochemical, and natural gas transmission sectors.
In natural gas transmission pipelines, trunnion ball valves provide reliable shutoff at compressor stations and meter runs. Refineries and petrochemical plants install them on process lines handling hydrocarbons and chemical media at elevated pressures. Offshore platforms and onshore production facilities use these valves for wellhead isolation and manifold systems. They also appear in power generation plants, water injection systems, and industrial gas supply networks where consistent sealing performance under pressure is required.
The trunnion-mounted ball remains in a fixed axial position, with upstream and downstream seat rings pushed against the ball by spring force and line pressure. This configuration achieves bi-directional sealing and allows the seats to absorb thermal expansion without binding. The trunnion bearings support both radial and thrust loads, reducing stem torque and enabling use of smaller actuators on large-bore valves.
The valve incorporates a fire-safe design per API 607 standards, where secondary metal-to-metal sealing maintains a basic shutoff level if soft seat materials are compromised by fire. An anti-static device provides electrical continuity between the ball, stem, and valve body to dissipate static charge buildup. The stem is designed with blow-out proof construction to prevent stem ejection under internal pressure.
Component | Standard Material Options |
|---|---|
Body | A216 WCB, A351 CF8 (304), A351 CF8M (316) |
Ball | A105 + ENP, 304 Stainless Steel, 316 Stainless Steel |
Seat | PTFE, RPTFE, Nylon, Devlon, Metal Seated |
Stem | A105, 304 Stainless Steel, 316 Stainless Steel |
Seat Seal | PTFE, Graphite |
Stem Packing | PTFE, Graphite, Flexible Graphite |
Valve design follows API 6D and ANSI B16.34 standards. Flange dimensions conform to ANSI B16.5 for Class 150 through Class 2500 ratings. Pressure testing is performed per API 598, including shell test and seat leakage test. Optional supplementary testing includes cryogenic testing, fugitive emission testing per ISO 15848, and gas seat testing.
Size Range | Pressure Class | Temperature Range |
|---|---|---|
DN50 - DN600 (2" - 24") | Class 150 - 600 | -29°C to 180°C (soft seat, PTFE) |
DN50 - DN400 (2" - 16") | Class 900 - 1500 | -29°C to 180°C (soft seat, PTFE) |
DN50 - DN300 (2" - 12") | Class 1500 - 2500 | -29°C to 450°C (metal seated) |
Note: Temperature ratings depend on seat material selection. Cryogenic service down to -196°C is available with extended bonnet configurations. Consult factory for specific medium compatibility.
Each valve undergoes hydrostatic shell testing at 1.5 times the rated working pressure and low-pressure air seat testing before shipment. Material test reports (MTR) are provided for all pressure-containing parts. Additional certifications available upon request include CE marking per PED, third-party inspection certificates, and PMI (Positive Material Identification) reports for critical commercial procurement projects.
Trunnion ball valves have a fixed ball supported by trunnion bearings, which reduces operating torque and makes them suitable for high-pressure and large-bore applications. Floating ball valves rely on line pressure to push the ball against the downstream seat, and are more commonly used in lower-pressure, smaller-size applications.
Yes, spring-loaded seats on both sides of the ball enable bi-directional sealing. This means the valve can seal against pressure from either flow direction, which is useful for pipeline pigging and double block and bleed (DBB) configurations.
The valve can be supplied with manual gear operators, pneumatic actuators, electric actuators, or hydraulic actuators. ISO 5211 mounting pads are standard on most sizes, allowing direct actuator mounting without custom brackets.
Standard documentation includes material test reports and pressure test records. Additional certifications available upon request include API 6D monogram, CE/PED, ISO 9001 quality system certification, and specific project inspection requirements. Lead times for certified orders vary based on specification complexity.