The Flanged Concentric Butterfly Valves uses a polytetrafluoroethylene lined butterfly plate with a spherical seal surface. The valve operates light, tight sealing performance and long service life, and can be used for fast cutting or regulating flow. It is suitable for occasions requiring reliable sealing and good regulation characteristics. The valve body is divided into body type, and the seal at both ends of the valve shaft is controlled by the rotating base surface and the fluorine rubber between the butterfly plate and the valve seat, and the valve shaft is not contacted with the fluid medium in the cavity. It is widely used for the transportation of liquid and gas (including steam) in various types of industrial pipes, and has serious corrosive medium, such as sulfuric acid, hydrofluoric acid, phosphoric acid, chlorine gas, strong alkali, and aqua regia.