Discussion from the gas tightness of valves, valve selection

Valves are gas transmission and distribution , storage systems, safe operation and maintenance , renovation, development indispensable equipment . If the gas valve selection of inappropriate or poor quality , it may lead to leaks , stop and other accidents. When an accident occurs , ranging from affecting normal social life, production , heavy to the state, bringing heavy losses of life and property . Therefore, the gas valve must be carefully chosen .
At present China's natural gas industry to use gas valve from the structural form of three main categories, namely, gate valve, ball valve, butterfly valve and so on. The following aspects of the valve from sealing analysis and comparison :
As technology continues to improve , the safety of a variety of valve has also been improved. Parallel Gate Valve stem installed inside protective sleeve , so that stem from erosion of media ; shell using a specially designed " rib cage frame " , reducing the overall weight of the valve , enhanced strength and stiffness of the housing ; resilient elastic sealing valve seal , valve fully open or fully closed , sealing the valve cavity completely isolated from the same media to make the gate with a fire-resistant , high temperature resistance , corrosion resistance characteristics. Valve open and close with a fully enclosed indicator , so that the operator a clear understanding of the state in which the valve .
Ball also has a fire resistance, high temperature characteristics . Fire burned hot seat PTFE sealing material, metal seal seat and the various sealing parts can form a metal -to-metal seal structure, prevents gas diffusion media , to prevent the disaster continues to expand ; it also has anti-static structure, so that valve opening and closing process formed electrostatic into underground , to avoid accumulation of static electricity ignited the media , to ensure safety of equipment ; ball finite bit locking mechanism prevents the operator from misuse or illegal operations.
Vice isolation valve seal width is too narrow , likely to cause the valve flap closure process too far or not in place , the impact seal ; addition, since the sealing of - part of the rubber or PTFE, is easy on the gas erosion damage or loss , and fire when the temperature easily damaged, life is short.
Due to space constraints , the buried gas pipeline can only use butterfly valves. Election should be used more eccentric butterfly valve quality , sealed Teflon or hard high security seal material selection , testing must be accurately adjusted to the closed position.
Valves and ball valves from the structural characteristics and safety are more suitable for underground gas pipeline . But they also have their disadvantages. Ball from design to manufacturing needs a high level of technology , so its higher cost. When you need to rotate the valve opening and closing a lot of laps , opening and closing with a longer time . So we should be integrated in the selection of valves of various factors in ensuring the safe and reliable as far as cost savings , from this perspective, we should be based on the use of the gas pipeline pressure characteristics and rational use of valves, pipeline meets safe operation but also to reduce the cost and make the best use purposes.