The gate valve is a shutter of the opening and closing member. The direction of movement of the gate is perpendicular to the direction of the fluid. The gate valve can only be fully open and fully closed, and cannot be adjusted and throttled. The gate valve is sealed by the contact between the valve seat and the gate. Usually, the sealing surface will be welded with metal material to increase wear resistance, such as surfacing 1Cr13, STL6, stainless steel, and the like. The gate has a rigid gate and an elastic gate. According to the gate, the gate valve is divided into a rigid gate valve and a flexible gate valve.