The Right Ball Valves

What does the Valve Schedule say?

What do the Piping Standards say?

You are asking what the decision process is if a trunion or split body ball valve design is selected?

Start with the process pressure, temperature, fluid type.

Trunion design is for larger valves, >8"

SPlit body allow for in line maintenance.

Further investigation is needed!

I assume you are asking about full port valves and not reduced port valves.

The size of the valve is critical to the application. With larger sizes The differential pressure is what causes the ball to move (or float) against the downstream sealing surface and make the seal. If there is no (or low) differential pressure the two piece, three piece or floating ball valve should and will leak a little. (Because the ball falls to the bottom of the cavity. this provides a path around both ends of the ball. In my applications the have been superior compared to trunnion mounted.

Smaller sizes, less than four inches, the trunnion and plug valves worked well. For a trunnion valve to work the ball does not move downstream when pressure is applied. The seal comes from the ball always compressed between the two sealing surfaces or in a sleave. The "breakaway torque" is very high and if the product is sticky, can dry or polymerize, the torque to open may ecxeed the strength of the stem and twist or damage the fit. These valves have been known to be difficult to manage in applications where they do not get operated for long periods.