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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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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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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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In general, industrial valves don’t have to do a strength test in use. But repaired or corroded body and bonnet should do that. Common media used in valve pressure testing are water, oil, air, steam, nitrogen and so on. And valve pressure test methods of all kinds of industrial valves, including pneumatic, are as follows: 1.For ball valve The pneumatic test of the ball valve should be carried out ...
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If the medium remained in the cavity after the cryogenic gate valve is closed, the residue will gradually absorb the heat in the air and re-gasify. After the gasification, it will expand violently up to 600 times and generate extremely high pressure on the valve, which is called 'abnormal boost'. When the unusual occurrence happens, the wedge will be pressed firmly onto the seat and can’t be opene...
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