Valve control device is a fluid conduit, its basic function is on or off the flow of the pipeline medium, changing the medium flow, the flow direction of the medium changes, the pressure and flow control medium, to protect the normal operation of the pipeline.

Industrial valves large number of applications in Watt invented the steam engine, the past three decades, since the petroleum, chemical, power, metallurgy, shipbuilding, nuclear power, aerospace and other needs, the valve put forward higher requirements, prompting people to study and production of high parameters of the valve, working temperature from -269 ℃ ultra-low temperature to a high temperature 1200 ℃, even up to 3430 ℃, working pressure from ultra-high vacuum 1.33x10-8Mpa (1x10-1 mm Hg) to the high pressure 1460MPa, valve size from 1mm to 600mm, even up to 9750mm.

Valve material from cast iron, carbon steel to titanium and titanium alloy development, high-strength corrosion-resistant steel, valves driven approach developed from manual to electric, pneumatic, hydraulic, programmable, digital, remote control and so on.

With the continuous development of modern industry, growing demand valve, a modern petrochemical plant will need tens of thousands of kinds of valves, valve with volume. 

Opened and closed frequently, but often due to the manufacture, use selection, improper maintenance, the occurrence of run, run, drip, leak, thereby causing fire, explosion, poisoning, burns and accidents, or cause poor product quality, increased energy consumption, equipment corrosion material consumption increase, environmental pollution, and even cause accidents such as shutdown, has been uncommon, so people want to get high-quality valves, also requires improving the use of valves, maintenance level, then engaged in valve operation, maintenance personnel as well as engineering and technical personnel , put forward new demands, in addition to well-designed, reasonable selection of the correct operation of the valve, should also be timely maintenance, repair valves, the valve's "run, run, drip, leak," and all kinds of accidents to a minimum.

Keywords:knife gate valve,ball valve,globe valve,slurry gate valve