Valves are installed in a variety of piping systems, as a piping accessory, mainly used to control the pressure, flow and direction of the fluid, such as truncation, regulation, check, shunt, safety, decompression, etc. In fact, due to the fluid pressure, temperature, flow and chemical and physical properties of different fluid system control requirements and use requirements are also different. It is because of the particularity of the valve, also determines the complexity of the valve, so the type and quantity of the valve is incomparable to any kind of mechanical products.