To consider the differences between floating ball valve and trunnion mounted ball valves for selection: as floating ball valve, the ball is floating, the ball can produce a certain amount of displacement and pressed on the sealing ring on the export side under media pressure, which guarantee export side seal, it is forcing seals on single side. But the ball for trunnion mounted ball valve is fixed, it does not move under the compression, so, two sealing rings should have enough preload guarantee seal in design, it is a two-sided mandatory seal.
Usually in the upper and lower stem which is connected with ball equipped with thrust or plain bearings. Floating ball valve should consider that if sealing materials is able to withstand the spheres of media loads , because the load that ball work under medium all passed to the export seal . Therefore, this floating ball structure is widely used in the low pressure ball valves. In addition, the design should also take into account that large caliber ball valve operation requires greater torque.