Trunnion Mounted Ball Valve Advantages

Low Torque
A Trunnion Ball Valve uses a Trunnion, or lower stem to support the ball within the valve body. trunnion stem absorbs the thrust from the line pressure, preventing excess friction between the ball and seats, so even at full rated working pressure operating torque remains low. For eg.  6″  Class 300, the torque for a floating ball valve is 1350 N.m, while it is 780 N.m for a trunnion ball valves with the same size and pressure rating.

trunnion ball valve

Large Application
The Trunnion-Mounted Ball Valve are suitable for high pressure, middle pressure and low pressure rating. The trunnion ball valves can be used for large size ranges, up to more than 1000 mm bore size. The trunnion ball valves are suitable for oil, gas and water etc. Trunnion Ball Valves tend to be more expensive than their floating ball valves and build by more specialized manufacturers – there tends to be a lot more parts in a trunnion ball valve.  However, depending on the application, they can often be a better choice, expecially for higher pressures. Most of  the clients specify all ball valves 6″ and larger or class 600# and higher and are to be trunnion mounted.

Self Relief Pressure
For trunnion mounted ball valves with cavity relief, the seat is energized initially using the springs, but the main sealing force comes from the line pressure differential between the seat and the cavity. The springs get a seal started so that the pressure can build up and to seal the valve at low pressures. For cavity relief, all the cavity pressure has to overcome is the load generated by the springs – once the cavity pressure and line pressure are the same, the springs are the only thing generating the seal. It does not take much cavity overpressure to have this relieve and the valve will always relieve to the low pressure side.

Double Piston Effect Seat Upon Request
You can also get into double piston trunnion ball valves that DO NOT self relieve (seat seals by pressure in BOTH directions – if upstream seat fails, downstream seat maintains seal). Valves with DPE on both seats do need PSV’s.

© 2019 Relia Valve Co., Ltd. Trunnion ball valve manufacturer

Tel: + 86-577-86373155, E-mail: export@reliavalve.com