First, an overview Plug valve structure is simple, fast switching, fluid resistance, angular travel fast. In emergency situations such as accidents, can quickly connect or cut off the pipeline. Compared with gate valve and stop valve, the operation is more flexible and the switch is faster. Stopcock is a plug with a through hole as a hoist, plug body with the stem rotation, in order to achieve opening and closing movements. Small non-packing plug valve, also known as "Cork." Stopcock plug bodies are mostly cones (also cylindrical), and the valve body with tapered bore surface to form a sealing pair. Second, the soft seal plug valve soft seal plug valves are commonly used in harsh environments such as corrosive, highly toxic and highly hazardous media, strictly prohibited leaks occasion, and the valve material will not pollute the media. The valve body can be selected according to the working medium carbon steel, alloy steel and stainless steel. A. According to the use of temperature and working medium using F4, F46, PVDF, PP, PO, PE and other self-lubricating material bushing, lubrication, the whole process of sealing friction coefficient is small, plug body flexible operation, long service life . B. The valve body inlet and outlet end window design and dual groove seal ring structure, the cock in the rotation process, the sealing pressure between the sealing pressure is gradually changing until it reaches full open or fully closed position, to produce adequate sealing Pressure than the seal to achieve zero leakage. C. Dual groove seal ring can not only make the sleeve stable in the valve body does not produce displacement, but also absorb the temperature changes caused by the liner caused by micro deformation, while producing strong friction between the bushing and the cock, with automatic cleaning Role, improve the sealing surface of the service life. D. plunger at the top of the unique anti-lip seal design, the use of a soft seal material diaphragm and the metal diaphragm and adjusting the gasket combination can both adjust the seal than the pressure between the sealing surface, so that plug rotation flexibility, but also to ensure that into, Seal the outlet and center flange connections. E. Suitable for high erosion gas-solid. Liquid-solid media. Such as PVC, urea, the anhydride, caustic soda production facilities, or external media require high leakage, such as HF, phosgene and so on. F. medium can flow in both directions, the installation direction is unrestricted, online maintenance, more convenient to use G. unique design to prevent static electricity, fire safety, safe to use. Third, the oil-lubricated hard-sealed plug valve Oil-lubricated hard-sealed plug valve can be divided into conventional oil-lubricated plug valves and pressure-balanced plug valves. Special grease from the top of the plug body into the cone between the body and plug to form a film to reduce valve opening and closing torque, improve sealing and service life. Its working pressure up to 64MPa, the maximum working temperature up to 325 degrees, the largest caliber up to 600mm. 1, the conventional oil-lubricated plug valve A. Conventional hard-sealed plug valve, cock plug cones installed formally. In order to reduce the friction between the valve body and the plug sealing surface, the sealing structure of the valve is generally used to lubricate the valve 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 a layer of oil film between the valve body and the plug cone surface, which can be closed and lubricated, and the opening and closing is easy. B. In order to further reduce the opening and closing force of the stopcock, the method of reducing the stopcock diameter is usually adopted. Therefore, the stopcock usually adopts a rectangular runner. This method increases the fluid resistance of the stopcock while reducing the opening and closing torque of the stopcock C. Stopcock Cone Sealing STL alloy or surface hardening technology to enhance the wear resistance and corrosion resistance of the sealing surface, long service life D. Rotor cone surface to the mirror surface, and the body seal Surface grinding, with a lower opening and closing torque. 2, pressure balanced plug valve In order to reduce the conventional hard seal plug valve torque, often using pressure balanced plug valve. In addition to the pressure balanced plug valve has the characteristics of the conventional oil-lubricated plug valve, there are the following characteristics: A. Pressure balanced plug cock plug conical way of mounting. There is a check valve in the upper part of the cock plug cone. When the valve is closed, due to the poor cross-sectional area of ​​the plug cone, the high-pressure sealing oil is injected to lift the plug body upwards so that the sealing face of the plug body and the valve can be better sealed. B. At the moment when the valve is open, the pressure in the lower chamber of the valve is balanced with the pressure of the medium in the pipeline. The high-pressure sealing oil in the upper chamber causes the plug body to be pushed downwards so that a slight gap occurs between the plug cone and the sealing surface of the valve body, Torque when rotating the plug body will be effectively reduced. Can also protect the seal pair. C. In high temperature conditions, the thermal expansion of the cock can be absorbed by its lifting, to avoid wedging the seal pair. Oil-lubricated hard-sealing plug valves, although the use of oil lubrication can reduce the opening and closing torque, but it may cause contamination of the medium. Therefore, select the actual conditions for sealing oil.