Leakage problems in fixed ball valves and floating ball valves

The seat spring at the outlet end of a fixed ball valve is not subject to any shocks, so there’s no need to worry about that. The floating ball itself provides a secure seal at the outlet end; it’s possible for the medium to enter the valve chamber. However, if the design is proper, the sealing surface at the inlet end will not come loose. Moreover, during the opening and closing process, the medium will definitely enter the valve chamber, so its presence there does not affect its functionality.

Thank you. Regarding your answer, there’s one thing I’m not quite sure about: the seat of a fixed ball valve is floating, and it’s the spring on the back side that presses against the ball to create a seal. If the flow rate is high enough, won’t this cause stress on the spring of the seat at the outlet? Thank you.

The ball valve seat is not directly exposed to the flow of the medium; it is protected behind the ball

If a fixed ball valve is in the closed position with the ball in that position, the pipeline is sealed, and the medium will not impact the spring of the outlet valve seat. If the ball is in the open position, the medium still will not affect the valve seat spring. Generally, during those brief moments when the pipeline is first opened or closed, there are significant fluctuations in pipeline pressure; however, when the pipeline is either closed or open, there are hardly any pressure fluctuations. Even if the medium were to impact the spring, it would not get damaged, as long as the deformation of the spring does not exceed its elastic limits. As for the issue of the spring losing its tightening force, that won’t happen either. Both fixed ball valves and floating ball valves have some form of pre-tightening force applied to them. In the case of fixed ball valves, this pre-tightening force is provided by springs, ensuring that the valve remains sealed even at low pressures. For floating ball valves, if they have soft seal valve seats, the pre-tightening force is achieved by adjusting the compression of the gasket, while hard seal valve seats rely on disc springs behind the valve seat for this purpose. In floating ball valves, the ball is pressed against the outlet valve seat by the force of the medium, thereby achieving sealing. As long as the valve seat does not undergo plastic deformation, the higher the pressure of the incoming medium, the better the sealing performance. Whether it is a fixed-ball valve or a floating-ball valve, applying preload is intended to ensure sealing at low pressures