Metal sealed butterfly valve has the advantages of compact structure, small volume, light weight, convenient operation, reliable performance and simple maintenance. It is widely used in thermal pipeline, boiler auxiliary system, petrochemical and metallurgical industries. It is used to cut off or adjust various corrosive and non corrosive media. Its products are divided into single eccentric, double eccentric and three eccentric structures. The metal hard seal butterfly valve is an eccentric structure. It is the extension and development of the general soft seal butterfly valve in the middle and high pressure field. Besides the original characteristics of the butterfly valve, it also has the characteristics of anti-aging, irradiation, durability, long life, high temperature and high pressure, and wide application range.