Threaded gate valve installation and maintenance should pay attention to the following: Handwheel, handle operation of the bellows valve can be installed in any position on the pipeline. Hand wheel, handle and Wei moving mechanism, do not allow lifting. The flow direction of the medium should be the same as the direction of the arrow shown on the valve body. Threaded gate valve, also known as cut-off, is the most widely used type of valve, it is popular because of the friction between the sealing surface during opening and closing process is small, more durable, open height is not small, easy to manufacture, Easy maintenance, not only for low pressure, but also for high pressure. Its closure principle is to rely on the valve stem pressure, so that the sealing surface of valve flap and seat sealing surface closely fit, to prevent the flow of media. Threaded gate valve only one-way flow of media, installation direction. Its structure is longer than the gate valve, while fluid resistance, long-term operation, the sealing reliability is not strong. Threaded gate valve is divided into three categories: Straight-through, right-angle and DC oblique stop valve. Threaded gate valve opens, the valve opening height, 25% to 30% of the nominal diameter, the flow has reached its maximum, indicating that the valve has reached the fully open position. Therefore, the full-stop position of the valve, valve stroke should be determined.