1. Butt flange flat plate valve seat seal structure should be elastic pre-tightening, upstream and downstream seals at the same time sealed structure. Seat and seal are always face-to-face seals. 2. Seat has a self-cleaning function, and the valve is opened or closed during the direct flow of air erosion. Seat should be made of lubricated, non-abrasive material. 3. Valve actuator failure does not affect the rest of the valve, maintenance and replacement work can be carried out without removing the valve. Welded flange plate gate valve at full open, the channel is smooth for the straight line, the flow resistance coefficient is minimal, no pressure loss, the ball can be used to clean the pipeline. Flat gate valve with self-sealing ability of the packing structure, without frequent adjustment, open, off extremely light, and reliable sealing, stuffing box at the auxiliary seal grease injection structure, the sealing performance is absolutely reliable, truly zero leakage; Solve the common Valve packing at the most easy to leak the ills. This article Keywords: gate valve