With the development of social economy, the use of valves is becoming increasingly widespread. There are many types and structures of valves used in pipelines, which are also easily damaged pipeline accessories. The maintenance of each type of valve should be carried out according to the specific structure. There are many types and structures of valves used in pipelines, which are also easily damaged pipeline accessories. The maintenance of each type of valve should be carried out according to the specific structure.

1. The maintenance of valve body and valve cover. The valve body and valve cover are the closed shells outside the valve, used to withstand the pressure of the medium, the additional force during operation, the weight of other parts of the valve, and the tightening force of the flange or thread at the connection The valve body and valve cover require a certain level of strength and stiffness, and their damage is mainly caused by local defects caused by medium corrosion, erosion, and mechanical damage. When the wall thinning due to corrosion or erosion affects their strength and stiffness, they cannot be repaired and should be replaced

During maintenance, the valve body and valve cover should first undergo a hydrostatic strength test, and then be inspected for tightness using water, compressed air, kerosene, or other media. Defects in the valve body and valve cover are generally repaired by welding, and corresponding welding rods and welding processes are selected according to the different materials Defective metal should be cleaned before welding repair, and after welding repair, it should be inspected and repaired, and stress should be eliminated

2. The maintenance of the packing chamber includes the replacement of packing and inspection and repair of the packing box. When selecting packing, the use conditions and medium conditions must be considered. Generally speaking, oil impregnated asbestos packing is suitable for air, steam, water, and heavy oil products at a certain temperature. Graphite asbestos packing can be used under high temperature and high pressure conditions, especially for graphite asbestos packing with steel wires, which has better pressure resistance Medium with high temperature and frequent temperature changes can be treated with asbestos and lead packing. Strong corrosive medium can be treated with PTFE impregnated asbestos packing or PTFE braided material