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What Is the Difference Between a Floating and a Trunnion Ball Valve?

Direct Answer

RelativerelativeFloating:seat loadTrunnion:seat loadFloating:torque (large/high-P)Trunnion:torque
Trunnion mounting carries the ball, cutting seat load and torque on large or high-pressure valves. Illustrative cross-section; not to scale.
How the ball is supportedFloating: seats hold ballball floats onto downstream seatTrunnion: pinned top & bottom
A floating ball shifts onto the downstream seat to seal; a trunnion ball is pinned, so seats take the load. Illustrative cross-section; not to scale.

A floating ball valve suspends the ball between two seat rings without mechanical support — line pressure pushes the ball against the downstream seat to achieve shutoff, making it suitable for small-to-medium bore, moderate-pressure service. A trunnion-mounted ball valve anchors the ball through upper and lower trunnion shafts, isolating seat load from line pressure — enabling reliable low-torque operation in large-bore, high-pressure applications within the industrial valve selection framework.