At present, as an equipment used for the on-off and flow control of pipeline, the centerline type butterfly valve has been widely used in many fields such as petroleum, chemical industry, metallurgy, hydropower. In the well-known butterfly valve technology, its sealing mostly adopts the sealing structure with the materials in rubber, polytetrafluoroethylene, etc. Due to the structural limitation, it cannot withstand high temperature and high pressure, and not resistant to corrosion and wear.
The structure feature of the centerline butterfly valve is that the shaft center of stem, the center of the disc and the center of the body are in the same position. The structure is simple and the manufacture is convenient.