1.1  Jam: When the medium temperature exceeds 80°C, the soft seats expand rapidly, the valve may happen to get jam or even cannot be operated. 

1.2  Jam: After some time running online, the operating torque increases significantly, the valve may happen to get jam or even cannot be operated.

1.3  Jam: For valves of the same specification and batch, part of valves may get jam after some time using.  

2.1  Internal Leakage: Under alternating medium pressure, cold flow of the valve seat may accelerates, lead to a shortened valve service life.  

2.2  Internal Leakage:For big size soft-seated ball valves (≥8 inch), large self-weight of the ball may causes uneven compression on the sealing surface, resulting in a short service life of the valve.