A ball valve whose ball has a stationary shaft is called as trunnion mounted ball valve. Trunnion mounted ball valves are mainly used for high pressure and large dimension. Based on different installation of sealing ring on seat, trunnion mounted ball valves have two types of structure: ball forward sealing seat, ball backward sealing seat.
Properties of trunnion mounted ball valves:
1. Double block and emission: Trunnion mounted ball valves adopt spring preload floating seat. No matter valves are opened or closed, upstream and downstream seat cuts off fluid. Rentate inside mesocoele of body is discharged through drain valve.
2. Automatic decompression: When the temperature of media in coelom of valves grows resulting in abnormal pressure rising, the pressure can be released automatically by seat instead of safety valves. It is vital for safety when valves transmitting fluid media.
3. Fire safe design: All of valves have fire safe design. Design and manufacturing follow API 607 and API 6FA standard.
Advantages of trunnion mounted ball valves:
1. Sealing added urgently with greases for rescue: Foreign materials contained in media or fire lead to seat lose its sealing by accident. Grease injection valves can connect with grease injection gun quickly. Inlet pump injects sealing greases into sealing parts of seat conveniently and quickly and relieves leakage.
2. Reliable stem sealing and low operation torque: Besides standard sealing ring, packing gland is also equipped with O-ring. Double sealing ensures reliability of stem sealing. Adding graphite packing and sealing grease injection lower leakage of stem to the lowest lever after fire. Sliding bearing on stem and thrust bearing make valve operation lightly and conveniently.
3. Full port and reduce port: Full port and reduce can be chosen based on requirements. Aperture of full port valves is consistent with inner diameter of pipeline, convenient for cleaning.
4. Stem can be lengthened: For installation and operation, stem can be lengthened. Ball valves with lengthened stem are quite suitable for pipelines which need to be laid underground, such as city gas. The dimensions of lengthened stem can be made to meet customers’ requirements.
5. Easy operation: Seat and bearing on stem have low friction coefficient and good self lubrication, which reduce greatly torque for operation valves. Nevertheless, without sealing grease, valves can also be operated easily for a long term.
Jan 29,2015
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