The valve is used to open and close the pipeline, control the flow direction, adjust and control the parameters of the transmission medium (temperature, pressure and flow) of the pipeline accessories. According to its function, it can be divided into shut-off valve, check valve, regulating valve and so on.

The valve is a control component in the fluid conveying system, which has the functions of shutting off, regulating, diverting, preventing countercurrent, regulating pressure, diverting or overflow pressure relief. Valves for fluid control systems range from the simplest globe valves to valves used in extremely complex automatic control systems in a wide variety of varieties and specifications.

Valves can be used to control the flow of various types of fluids such as air, water, steam, various corrosive media, mud, oil, liquid metal and radioactive media. Valve according to the material is also divided into cast iron valves, cast steel valves, stainless steel valves (201, 304, 316, etc.), chromium molybdenum steel valves, chromium molybdenum vanadium steel valves, biphase steel valves, plastic valves, non-standard valves and so on.