Full sealed butterfly-shaped isolation door with high temperature resistance

A full sealed butterfly-shaped isolation door with high temperature resistance comprises a cylindrical housing. Two ends of the housing are respectively provided with an inner end opening and an external end opening. In the housing, a place close to the inner end opening is provided with an annular seal seat fastened on the inner wall of the housing; the housing inner wall tightly abutted against the external end of the annular seal seat is fixedly connected with a protective ring; an annular expansion joint is disposed in the protective ring; the external side of the inner end of an annular seal sleeve in the housing is fixedly connected with the inner side of the annular seal seat; the external side of the external end of the annular seal sleeve is abutted against the annular expansion joint; a round valve cover is formed in the annular seal sleeve; the round valve cover and the annular seal sleeve are concentrically arranged; the external edge of the round valve cover is provided with a bead weld layer; an