The valve stem mainly has the advantages of being relatively compressible, capable of good heat preservation, and less prone to corrosion and rust. It has the sealing function of both sides, is relatively resistant to wear, and its service life is relatively long. Then there are several reasons why the valve stem is broken or deformed:
1. Area
The broken part of the valve stem is usually at the bottom of its upper and lower threads, because the area of ​​that place is relatively small, and the corresponding force concentration and exceeding the standard are prone to occur.
2. It breaks when opening
Generally speaking, the most likely occurrence of a broken valve stem is the moment it is opened. The main reason is that the gate has not separated from the valve seat, and the stem is broken at the root of the upper or lower thread. Under normal circumstances, it is considered that the gate is stuck. This is not the whole reason, and it is not the most important reason. .
3. Valve body
After the valve body is closed, abnormal temperature rise and pressure drop occur, that is, after the valve is closed, the fluid pressure in the middle cavity enclosed between the upstream and downstream sealing surfaces is much higher than the upstream pressure. The reasons are as follows:
(1) Expansion
(2) closed