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The blow-out proof stem is one of basic design features of ball valve. Ball valve stem is inserted from the valve body inside with integral T-type shoulder to provide blow-out proof effectively. It is internally inserted as a function of backseat to assure stem sealing safety. To describe it in details, the stem is sealed by o-rings & packing rings, and held in position by the stem housing whi...
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(6) Effect of surface hydrophilicity on sealing property The hydrophilicity of the surface affects the amount of leakage due to the characteristics of the capillary. When there is a thin film of oil on the sealing surface, it is necessary to increase the pressure of the water passing through the gap. Due to the good hydrophilicity of the metal surface, kerosene can easily penetrate the gap between...
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Anti-static device is another basic and mandatory design for ball valve. During the operation of valve, the constant friction between ball and soft seat will generate static electricity. The spark caused by static electricity may ignite the inflammable fluid inside the valve and cause a potential fire hazard. To get rid of the hidden danger, an anti-static device is invented for ball valve. Like t...
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These three materials of stainless steel 304, 304H and 304L are often used in valve industry. Among three, 304 is the most common one, like SS304 ball valve, SS304 gate valve, SS304 globe valve, SS304 check valve we often see. In fact, according to the content of chromium and nickel, they all belong to stainless steel 304, since they all contains 18% chromium (Cr) and 8% nickel (Ni). The ma...
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There are many ways to classify plug valves. In this article, we will introduce four main type of plug valves. 1. Lubricated Plug Valve A lubricated plug valve functions with the help of a lubricant (a base oil and viscosity improver) which is injected between the plug and body seat facing to reduce the frictions between them. The lubricated plug valve must be resealed after a few cycles. Due to i...
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For trunnion-mounted ball valve, there is a metal seat ring and a soft seat insert to ensure the sealing performance of seat. The seat inserts are element mounted inside a metal seat ring and perform the same sealing functions as seat ring. There are mainly two types of seat insert materials, elastomeric and thermoplastic. Elastomeric seat insert is softer to achieve zero leakage of ball valve. Wh...
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