Trunnion Mounted Ball Valve is a specially designed fixed ball valve, the core feature of which is that the ball is rigidly fixed in the valve body by upper and lower trunnions (support shafts). The following is a detailed description of its key features and working principles:
- Core structural features
1.Trunnion fixed design
The ball is connected to the valve body through two rigid trunnions, so that the ball will not move under fluid pressure and only rotate around the trunnion axis.
2. Valve seat sealing mechanism
Spring loaded valve seat: The valve seat and the ball are tightly fitted by the spring preload to ensure initial sealing.
Pressure assisted sealing: The medium pressure pushes the valve seat against the ball. The higher the pressure, the stronger the sealing effect (bidirectional sealing capability).
- Differences from traditional floating ball valves
| Features | Trunnion Ball Valve | Floating ball valve |
|---|---|---|
| Sphere Fixing Method | Rigid fixing of the trunnion | Only stem connection, ball can float |
| Operating Torque | Low (more stable at high pressure) | Torque increases dramatically at high pressure |
| Applicable working conditions | High pressure, large diameter, high temperature | Low pressure, small diameter |
- Working Principle
Open/Close Action:
The rotating valve stem drives the ball to rotate 90°, so that the ball hole is aligned with the pipeline (fully open) or vertical (fully closed).
Sealing Process:
When closed, the spring preload + medium pressure work together to achieve zero leakage sealing.
Special anti-flyout structure prevents the valve stem or ball from detaching under high pressure (safety design).
- Core Advantages
High Pressure Tolerance: The trunnion structure disperses the fluid pressure and avoids excessive wear of the valve seat.
Low operating torque: Suitable for large-diameter valves (such as ≥8 inches commonly used in oil pipelines).
Medium Adaptability: Can handle particle-containing, high-viscosity media (such as slurry, oil).
- Typical Application Areas
Energy Industry: High-pressure cutoff of oil/gas pipelines.
Heavy Industry: Chemical reaction unit, metallurgical high-temperature fluid control.
Harsh working conditions: Corrosive media control in water treatment, mining, and papermaking.
