What is the working principle of the trunnion ball valve

1. Ball Fixing and Trunnion Support

The core components of a trunnion ball valve are the ball and trunnions. The ball is secured to the top and bottom of the valve body via trunnions. This design prevents ball drift under media pressure, ensuring stable sealing performance. The trunnions not only provide mechanical support but also effectively distribute fluid pressure stress on the valve seat and seals, extending valve life.

2. Sealing Mechanism

The trunnion ball valve features a spring-loaded seat design. When media pressure acts on the seat, the spring automatically preloads, tightly fitting the seal against the ball, achieving a reliable bidirectional seal. This design maintains excellent sealing performance in both low- and high-pressure systems while reducing seat wear caused by sudden pressure changes.

3. Low Operating Torque
Because the trunnion design reduces lateral force exerted by the fluid on the ball, the operating torque of a trunnion ball valve is significantly lower than that of a comparable floating ball valve. This makes the valve easy to operate and is particularly suitable for applications with frequent on/off cycles, such as pipeline bypass, batch control, and emergency shutdown services.

4. High-Pressure and High-Temperature Adaptability
Trunnock ball valves are particularly well-suited for high-pressure and high-temperature applications. Their compact construction and optimized flow path design allow them to withstand operating pressures up to 10,000 psi (690 bar) and temperatures up to 232°C (450°F). Furthermore, the trunnion design allows the valve to handle high flow demands in large-diameter pipelines while reducing pressure drop and improving system efficiency.

5. Bidirectional Sealing and Leak-Proof Design
Trunnock ball valves typically utilize a double-seat design, with the upstream and downstream seats independently floating, ensuring a seal regardless of flow direction. This design not only improves valve reliability but also reduces the risk of leakage.

6. Material Selection and Corrosion Resistance
High-performance trunnion ball valves are typically manufactured from corrosion-resistant materials such as 316 stainless steel, PEEK (polyetheretherketone), or PTFE (polytetrafluoroethylene) to accommodate diverse media environments. These materials not only enhance valve durability but also ensure long-term stability under harsh operating conditions.

7. Quick Closure and Flow Control
The trunnion ball valve can be quickly closed or opened with a 90-degree rotation, making it ideal for applications requiring rapid shutoff or restoration of fluid flow. Furthermore, its full-bore design allows for maximum flow, reducing pressure drop and improving overall system efficiency.