Bent valve stems are generally common in gate valve failures. Of course, ball valves and globe valves may also occur. The main cause of valve stem bending is stress. The main source of stress is that the valve stays in the same state for a long time without movement, so that the valve stem is squeezed by the upward stress and the stress concentration at the copper sleeve cannot be eliminated, and the valve stem is bent at the copper sleeve. Of course, this is related to the stem material and valve structure. However, it is directly related to the state of use of the valve.
The usual processing method is to process a new replacement according to the size. Pay attention to several points of processing here. First, the size must be accurate to ±0.01, second, the direction and pitch of the thread must be accurate, third, polishing to the mirror effect is a must, fourth, the choice of material is very important, general requirements Quench after processing.
The usual cause of valve stem fracture is due to improper operation. When the valve is in a state of slight internal leakage, our operators always feel that it is not closed in place when closing the valve, so the force is far greater than the design torque to close, which causes the valve stem to break. Therefore, it is very important to use the appropriate torque when operating the valve. Of course, some valves are difficult to operate because of foreign objects stuck or other reasons, but this is not the reason that the design torque should be used to operate. As the processing requirements for replacement are consistent with the above processing requirements!