The valve is fluid pipeline control device, its basic function is to connect or cut off the pipeline medium circulation, changing the medium circulation, change the direction of the flow medium, medium pressure and flow regulation, to protect the normal operation of pipeline equipment.
Application of a large number of industrial valves after Watt invented the steam engine, the past twenty or thirty years, due to the oil, chemical, power, metallurgy, shipbuilding, nuclear energy, aerospace and other aspects, put forward higher requirements on the valve, spurred the research and production of high parameters of the valve, its working temperature from ultra low temperature -269 C to 1200 degrees, even up to 3430 DEG C, working pressure from vacuum 1.33x10-8Mpa (1x10-1 mm Hg) to ultra high pressure 1460MPa valve size from 1mm to 600mm, and even reached 9750mm, the valve material from cast iron, carbon steel to the development of titanium and titanium alloy, high strength and corrosion resistant steel, valve drive from the manual to the development of electric, pneumatic, hydraulic, control, numerical control, remote control etc..
With the continuous development of modern industry, the valve demand continues to grow, a modern petrochemical device requires tens of thousands of only a wide range of valves, large valve usage. Open and closed frequently, but often because of the manufacture and the use of selection, improper maintenance, occurrence of leakage phenomenon caused by fire, explosion, poisoning, burns or accidents caused by the poor quality of the products, improve the energy consumption, equipment corrosion, material consumption increase, environmental pollution, and even cause the production accident, has It is often seen. therefore, people want to obtain the high quality of the valve, it also requires improving the use of the valve, when the valve in the maintenance level, operating personnel, maintenance personnel and engineering and technical personnel, put forward new requirements, in addition to elaborate design, reasonable selection and correct operation of the valve, but also timely maintenance and repair of the valve, the valve. "Run, run, drip, drain and all kinds of accidents to a minimum.