1 working principle and function of gate valve:
Gate valve belongs to block valve type, which is usually installed on the pipe with diameter greater than 100mm to block or connect the medium flow in the pipe. As the disc is a gate plate, it is generally called gate valve. The gate valve has the advantages of less switching force and less flow resistance. However, the sealing surface is easy to wear and leak, the opening stroke is large, and the maintenance is difficult. The gate valve cannot be used as a regulating valve. It must be in the fully open or fully closed position. The working principle is: when the gate valve is closed, the stem moves downward depending on the height of the gate valve sealing surface and the valve seat sealing surface, which are smooth, flat and consistent. They fit each other to prevent the medium from flowing through, and rely on the top wedge to increase the sealing effect. Its closure moves vertically along the centerline. There are many kinds of gate valves, which can be divided into wedge type and parallel type. Each type is divided into single ram and double ram.
The gate valve body adopts the self sealing form. The connection mode of the valve cover and the valve body is to use the upward pressure of the medium in the valve to compress the sealing packing to achieve the purpose of sealing. High pressure asbestos packing with copper wire is used for sealing of gate valve.
Gate valve structure is mainly composed of valve body, bonnet, frame, stem, left and right valve disc, packing sealing device, etc.
The valve body material is divided into carbon steel and alloy steel according to the pressure and temperature of the pipeline medium. Generally installed in the valve of superheated steam system, t > 450 ℃, the valve body is made of alloy material, such as boiler exhaust valve, etc. If the valve is installed in the water supply system or medium temperature T ≤ 450 ℃, the valve body material is carbon steel.
Gate valves are generally installed on steam water pipes with DN ≥ 100mm. There are three types of nominal diameters of gate valve in the first stage wgz1045 / 17.5-1 boiler in Zhangshan, i.e. DN300, dnl25 and dnl00.
Post time: Apr-07-2020