Pneumatic pipeline pressure maintaining device

The utility model relates to the technical field of starting pipelines, in particular to a pneumatic pipeline pressure maintaining device which comprises a main air cylinder, the main air cylinder is communicated with a sliding pipe through a pneumatic pipeline body, a movable plate is slidably connected into the sliding pipe, the bottom end of the movable plate is fixedly connected with a valve plate through a stretching rod, and the bottom end of the sliding pipe is fixedly connected with a valve frame. The bottom end of the stretching rod is fixedly connected with the valve plate, a pressure maintaining device is arranged at the rear end of the sliding pipe, an auxiliary starting mechanism is arranged at the top end of the valve frame, the pressure maintaining device comprises two air conveying pipes, and one ends of the two air conveying pipes are communicated with the sliding pipe. Compared with the prior art, cost is wasted due to the fact that a main air cylinder large in air supply amount needs to be