In order to achieve zero leakage inside and outside the valve seal, save energy, protect the environment and improve work efficiency, the valve must have a reliable sealing performance. The sealing parts of the valve mainly include the contact between the two sealing surfaces of the opening and closing member and the valve seat, the contact between the valve stem and the valve cover, the sealing position of the valve stem, the gasket contact between the valve body and the valve cover, and the like. Among them, the opening and closing parts and valve seat leakage between the two sealing surfaces is called the valve's internal leakage, and the valve stem and valve cover, valve stem seal and the valve cover sealing surface leakage between the leakage as the valve. Valve leakage will affect the ability of the valve to cut off the medium. Leakage of the valve will result in the loss of transport medium or pollute the environment, causing serious accidents in severe cases. For flammable, toxic or radioactive medium, the valve leakage phenomenon is even more not allowed to happen. The sealing performance of the valve is an important technical indicator to measure the valve quality. The national standards set the relevant requirements for the technical requirements of sealing the steel gate valve and the steel stop valve. The sealing effect of the steel gate valve and the stop valve is related to many aspects of valve material, processing equipment, tooling manufacturing, heat treatment, processing technology, form tolerance and part machining accuracy, and a certain technology can not meet the design requirements Will directly affect the sealing effect. According to the relevant standards, the valve seal should have a conical or spherical sealing structure. However, the conical or spherical sealing structure has some unfavorable factors with respect to the planar sealing structure, such as the friction phenomenon of the sealing surface, the difficulty of maintenance, the high processing difficulty and the increase of the production cost. The result is an increase in production costs and a lack of competitiveness of the product. At the same time, the valve sealing performance is also difficult to meet the standard technical requirements, often after several sealing performance test will fail.
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