Valve maintenance method
The valve is a control component in the fluid conveying system, which has the functions of cut-off, regulation, diversion, prevention of reverse flow, stabilization, diversion or overflow and pressure relief. Valves used in fluid control systems, ranging from simple shut-off valves to various valves used in more complex automatic control systems, have a wide range of varieties and specifications.
There are many types of valves used in pipelines, with different structures, and they are the most easily damaged pipeline accessories. The maintenance of each valve should be carried out according to the specific structure. The specific maintenance methods are as follows:
 
1: Maintenance of the valve body and bonnet. The valve body and bonnet are closed shells outside the valve 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 bonnet are required to have a certain strength and rigidity. Their damage is mainly local defects caused by medium corrosion, erosion and mechanical damage. When the wall is thinned due to corrosion or erosion, it will affect their strength and When rigid, it cannot be repaired and should be replaced.
 
During maintenance, the valve body and bonnet should be tested for hydraulic strength first, and then water, compressed air, kerosene or other media should be used to check their tightness. The defects of the valve body and bonnet are generally repaired by welding, and selected according to the different materials. Corresponding welding rod and welding process. Defective metal should be cleaned before welding repair, and inspection and repair should be carried out after repair welding, and stress should be eliminated.
 
2: Inspection and repair of the packing room The inspection and repair of the packing room includes replacement of packing and inspection and repair of stuffing box parts. When selecting packing, use conditions and medium conditions must be considered. Generally speaking, oil-invaded asbestos packing is suitable for air, steam, and steam at a certain temperature. Water and heavy oil products. Graphite asbestos packing can be used under high temperature and high pressure, especially graphite asbestos packing with steel wire is more resistant to pressure. Asbestos and lead packing can be used for high temperature and frequently changing media. Strong corrosive media can be used to invade PTFE asbestos packing or PTFE braid.