The valve is an important part of the pipeline system, and the maintenance of the valve is one of the main tasks in the production operation. The Lanzhou high-pressure valve gearbox on the Sichuan-to-East Gas Transmission Pipeline has accumulated rust when it is put into use, which increases the difficulty of maintenance and safety risks. Starting from the gear box structure, the paper analyzes the sealing point of a typical Lagoon valve gear box, explores the cause of fluid accumulation in the gear box, uses contact sealing technology, and uses a reasonable combination of sealing elements in the structural space to strengthen the gear box seal and completely change the gear The closed condition of the box realizes the isolation of water vapor and ensures the dry running conditions of the gear box.