Valves are pipeline accessories used to open and close pipelines, control flow direction, and regulate and control the parameters of the conveyed medium (temperature, pressure, and flow). According to their function, they can be divided into shut-off valves, check valves, control valves, etc.

Valves are control components in fluid transport systems, with functions such as shutting off, regulating, diverting flow, preventing backflow, stabilizing pressure, splitting flow, or relieving pressure. The valves used in fluid control systems range from simple shut-off valves to various types of valves used in highly complex automatic control systems, with a wide variety and specifications.

Valves can be used to control the flow of various types of fluids including air, water, steam, various corrosive media, slurry, oil products, liquid metals, and radioactive media. Valves can also be classified by material, such as cast iron valves, cast steel valves, stainless steel valves, chrome-molybdenum steel valves, chrome-molybdenum-vanadium steel valves, duplex steel valves, plastic valves, and custom non-standard valves.