Fully lined butterfly valve is a kind of valve that opens, closes and regulates the fluid passage by turning the disc around 90 degrees. Fully lined butterfly valve is not only simple in structure, small in volume, light in weight, less in material consumption, small in installation size, but also has small driving moment, simple in operation and fast in operation. It also has good flow withering function and closing and sealing characteristics. It is one of the fastest growing valve varieties in recent decades.