The gate valve is opening and closing parts are gates, and the movement direction of the gate is perpendicular to the direction of the fluid. The gate valve can only be fully opened and fully closed, and cannot be adjusted or throttled. The gate has two sealing surfaces. The two sealing surfaces of the most commonly used mode gate valve form a wedge shape. The wedge angle varies with the valve parameters, usually 5°, and 2°52' when the medium temperature is not high. The gate of the wedge gate valve can be made into a whole, called a rigid gate; it can also be made into a gate that can produce a slight deformation to improve its processability and compensate for the deviation of the sealing surface angle during the processing. This gate is called an elastic gate. When the gate valve is closed, the sealing surface can be sealed only by the medium pressure, that is, the sealing surface of the gate is pressed against the valve seat on the other side by the medium pressure to ensure the sealing of the sealing surface. This is self-sealing. Most gate valves use forced sealing, that is, when the valve is closed, the gate is forced to press against the valve seat by external force to ensure the sealing of the sealing surface.