What is the failure analysis and treatment of globe valve
The leakage of the bellows globe valve of the gate valve manufacturer is usually divided into external leakage and internal leakage, and there are many reasons for the leakage. Under normal circumstances, the liquid medium contains solid impurities, which will damage the sealing surface and cause failure. Combined with on-site application analysis, the main reasons for valve stem leakage of gate valve manufacturers are related to the operation mode, valve structure and working environment.
1. Structure:
The valve stem adopts a double sealing structure of bellows and packing. The bellows is welded with the inner ring and the outer ring to form a bellows assembly, and then welded with the valve stem and the guide body to prevent the medium from leaking through the valve stem. The valve stem moves up and down from the flat key I until the upper end face of the flat key I contacts the lower end face of the lower packing. Since the lower packing is made of PTFE, if the valve is opened too much, the flat key I will be embedded in the packing, the valve will no longer be able to open and close, and the bellows assembly will be crushed to death, causing the medium to leak along the valve stem. The tensile length and compression amount of the bellows are determined according to the valve stroke. If stretched or compressed beyond the limit, the bellows can be damaged, causing the small braided tube to rupture and seal failure. Therefore, it is necessary to increase the opening and closing limit device of the valve, so that the bellows can expand and contract within the design range during the opening and closing of the valve.
2. Working environment:
The poor working environment of the bellows globe valve of the gate valve manufacturer is also one of the reasons for its failure. Because the bellows globe valve installed on the ship has been working in the salt fog environment for a long time, the upper part often has condensate droplets, which causes the corrosion of the upper thrust ball bearing. In severe cases, it will lead to contact corrosion of the valve stem.
3. Operation:
If the bellows globe valve of the gate valve manufacturer opens and closes excessively in use, it may not meet the corresponding performance requirements. If the valve is closed excessively, it may damage the sealing surfaces, causing the seal to fail when the valve is reused. If the valve is opened excessively, the bellows assembly may be manipulated, causing the valve to leak.