Oil-lubricated hard-sealed plug valves can be classified into conventional oil-lubricated plug valves and pressure-balanced plug valves. Special grease is injected from the top of the plug body between the cone hole of the valve body and the plug body to form an oil film to reduce the valve opening and closing torque, improve the sealing performance and service life. The working pressure can reach 64MPa, the maximum working temperature can reach 325 degrees, and the maximum diameter can reach 600mm.
1, the conventional oil-lubricated plug valves
A. Conventional hard-sealed plug valve, the plug cone is mounted in a formal dress. In order to reduce friction and the valve plug sealing surface, the valve seal construction generally sealed grease seat. The high-pressure sealing oil injected from the high-pressure oil nozzle forms a high-pressure sealing ring around the cock, that is, there is an oil film between the valve body and the sealing surface of the cock cone, which can be closed and lubricated, and is easy to open and close.
B. In order to further reduce the opening and closing force rejection of the plug valve, the method of reducing the diameter of the plug is usually adopted. Therefore, the plug valve usually adopts a rectangular flow passage. This method increases the fluid resistance of the plug valve while reducing the opening and closing torque of the plug valve.
C. Surfacing the STL alloy material in the sealing part of the taper cone or using surface hardening technology to enhance the wear and corrosion resistance of the sealing surface and long service life
D. The surface of the taper cone is finely ground to the mirror surface, and the sealing surface of the valve body is ground to have a lower opening and closing torque.
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