Valves are pipeline accessories used to open and close pipelines, control flow direction, and adjust and control the parameters (temperature, pressure, and flow) of the conveying medium. According to their functions, they can be divided into shut-off valves, check valves, regulating valves, etc.
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. Valves are also divided into cast iron valves, cast steel valves, stainless steel valves (201, 304, 316, etc.), chrome-molybdenum steel valves, chrome-molybdenum-vanadium steel valves, duplex steel valves, plastic valves, non-standard custom valves, etc. according to the material.