A trunnion mounted valve means that the ball is con- strained by bearings and is only allowed to rotate, the majority of the hydraulic load is supported by the Sy- stem constraints, resulting in low bearing pressure and no shaft fatigue.
How do you install a slip ball valve?
https://www.youtube.com/watch?v=SZIVueYA6bU
What is the difference between trunnion and floating ball valves?
The ball in a trunnion ball valve is supported by the stem and trunnion, reducing the operating torque, while the seats are spring loaded. In a floating ball valve, the ball floats and the seats are fixed while the ball is only supported by the stem.