The function of trunnion ball valve

Q: What is the main function of a trunnion ball valve in pipeline systems?

A: The trunnion ball valve is a quarter-turn shut-off valve built with a fixed ball supported by upper and lower trunnion shafts. Its core function is to reliably block or permit fluid flow within pipelines. The trunnion structure bears pipeline pressure thrust and keeps the ball stable, while spring-loaded seats press against the ball to achieve tight shut-off. It can also be configured with double block and bleed function for cavity pressure relief and seal verification, protecting system safety during isolation and maintenance.

Conclusion: Therefore, the main function of the trunnion ball valve is to provide stable, tight fluid shut-off for high-pressure and large-diameter pipelines, with optional cavity venting capability to guarantee operational safety.

The principle of using trunnion ball valve

Q: What is the working principle of a trunnion ball valve?

A: Its operation relies on 90-degree rotation of the ball, and the ball is mechanically fixed by trunnion supports instead of floating freely. When opening, the ball’s through bore aligns with the pipeline to allow medium to pass. When closing, rotating the ball makes the solid surface contact the upstream and downstream spring-loaded seats. Line pressure pushes seats toward the stationary ball to form sealing. The trunnion absorbs fluid thrust, avoiding excessive friction between ball and seats. For DBB style, the trapped pressure in the body cavity between two seats can be vented via a bleed port.

Conclusion: Therefore, the operating principle of the trunnion ball valve depends on a trunnion-fixed ball and spring-loaded seat sealing. Pressure loads are borne by trunnions to lower operating torque and wear, achieving reliable on-off control and optional cavity pressure management.

The operating conditions and advantages of trunnion ball valve

Q: What are the common applications and key advantages of trunnion ball valves?

A: This valve is widely used in oil & gas, petrochemical, power, and long-distance pipeline industries, suitable for large diameter, high pressure, high temperature, and corrosive working media. Its key advantages include:

Low Operating Torque: The trunnion takes pressure thrust, greatly reducing friction, so smaller actuators can be adopted.

Long Service Life: Fixed ball reduces seat abrasion under high pressure, improving durability. Reliable Bi-directional Sealing: Spring preloaded seats deliver bubble-tight shut-off for bidirectional flow.

Customizable DBB / DIB Function: Integrate double block and bleed structure for safe isolation and seal test.

Wide Material Options: Available in carbon steel, stainless steel, duplex steel and alloy for corrosive media.

Full bore design option: Enables pipeline pigging and minimizes pressure drop.

Conclusion: Therefore, the trunnion ball valve delivers stable shut-off performance for severe high-pressure pipeline services. With benefits of low torque, long lifespan and flexible configurations, it is the preferred isolation valve for critical process pipelines.

As a leading industrial valve manufacturer, SJ is proud to offer its high-performance trunnion mounted ball valve solutions, specifically engineered for critical isolation in oil, gas, and chemical applications. Our trunnion ball valve adopts a robust fixed-ball trunnion design, which transfers pipeline pressure thrust to the trunnion bearings rather than squeezing the valve seats. This design effectively cuts operating torque and seat wear, suitable for large size and high pressure pipeline services. It can be built with integral double block and bleed function for cavity depressurization and seal integrity checking. Available in multiple material options including LF2, F304, F316L and duplex stainless steel, our trunnion ball valve complies with API 6D, fire-safe and NACE standards, to deliver the safety, efficiency, and durability your process lines demand.