Structure of gate valve

1. Use of gate valve:

Gate valve is a kind of shut-off valve used to connect or cut off the medium in the pipeline. The gate valve has a wide range of use. At present, the performance parameters of commonly used gate valves produced in China are: nominal pressure PN0.1 ～ 32MPa; nominal diameter DN15 ～ 1800mm; working temperature t≤550 ℃.

2.The characteristics of the gate valve

   (1) Low fluid resistance Because the medium channel inside the gate valve body is straight through, the medium does not change its flow direction when flowing through the gate valve, so the fluid resistance is small.

   (2) Low opening and closing resistance Because the gate movement direction is perpendicular to the medium flow direction when the gate valve is opened and closed, compared with the stop valve, the opening and closing of the gate valve is labor-saving.

   (3) Unlimited flow direction of the medium The medium can flow from any direction on both sides of the gate valve, which can achieve the purpose of use.

   (4) Short structure length Because the gate of the gate valve is placed vertically in the valve body, and the shut-off valve disc is placed horizontally in the valve body, the structure length is shorter than that of the stop valve.

   (5) Good sealing performance The sealing surface is less eroded when fully opened.

   (6) The sealing surface is easy to damage. There is relative friction between the two sealing surfaces where the gate and the valve seat are in contact during opening and closing, which is easy to damage and affect the sealing performance and service life.

   (7) Long opening and closing time and large height Because the gate valve must be fully opened or closed when it is opened and closed, the gate stroke is large, a certain amount of space is required for opening, and the external dimensions are high.

   (8) The structure is complicated, there are many parts, it is difficult to manufacture and maintain, and the cost is higher than the globe valve.

     3.the structure of the gate valve

    The gate valve is mainly composed of valve body, valve cover or bracket, valve stem, valve stem nut, gate plate, valve seat, stuffing box, sealing packing, packing gland and transmission device. Figure 2-1 is a typical flange connection Rod wedge spring gate valve. For large-diameter or high-pressure gate valves, in order to reduce the opening and closing torque, a bypass valve (stop valve) can be connected in parallel with the inlet and outlet pipes adjacent to the valve. Then open the gate valve. The nominal diameter of the bypass valve is not less than DN32.