Trunnion mount ball valve

A trunnion mount ball valve has the ball connected to a shaft above and below the ball. The upper shaft transmits the actuator torque to the ball and both shafts together hold the ball in a centralized position against the line pressure. Bearings are typically provided between the trunnion shafts and the valve body. The advantage of this approach is that a lower torque is required to move the ball when compared at similar pressures to a floating ball valve. 

Both floating and trunnion-mounted designs are available with other design variations that include metal seied valves, soft seated valves, top-entry valves, end-entry valves, and split body valves. Valves in all these design variations are available as either full port or reduced port. Port refers to the round-bore fluid flow area through the ball. Full port valves have a bore that is approximately equal to the inside diameter of the mating pipe. Reduced port valves have a bore that is approximately equal to the inside diameter of pipe one size smaller than full bore. 

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