1. Shut off valve: This kind of valve is open and close. Standing on the inlet and outlet of cold and heat sources, the inlet and outlet of equipment, pipe branch lines (including riser), can also be used as water and air discharge valve. Common shut-off valves include gate valve, globe valve, ball valve and butterfly valve. 2. Check valve: This kind of valve is used to prevent the backflow of the medium, the use of the fluid's own kinetic energy to open, reverse flow automatically closed. Standing at the pump outlet, trap outlet and other places do not allow the reverse flow of fluid. 3. The regulating valve: the regulating valve can according to the direction and size of the signal, change the spool stroke to change the valve resistance number, so as to achieve the purpose of regulating the flow of the valve. The regulating valve breaks up the regulating valve and the automatic regulating valve, and the manual or automatic regulating valve is divided into many kinds, its regulating performance is also different.Shandong Zhongao Steel Co. LTD. is a large-scale iron and steel enterprise integrating sintering, iron making, steel making, rolling, pickling, coating and plating, tube making, power generation, oxygen production, cement and port. The main products include sheet (hot rolled coil, cold formed coil, open and longitudinal cut sizing board, pickling board, galvanized sheet), section steel, bar, wire, welded pipe, etc. The by-products include cement, steel slag powder, water slag powder, etc. Among them, fine plate accounted for more than 70% of the total steel production.1. The valve is used to open and close the pipeline, control the flow direction, adjust and control the transmission medium parameters (temperature, pressure and flow) of the pipeline accessories. According to its function, can be divided into shut-off valve, check valve, regulating valve and so on. 2. The valve is the control part of the fluid delivery system, with cut-off, regulation, diversion, prevent countercurrent, pressure regulation, shunt or overflow pressure relief functions. Valves used in fluid control systems range from the simplest globe valves to the most complex automatic control systems used in a wide variety of varieties and specifications.