D63, D963, D663, D363 (H, Y, F) - PN6, 10, 16, 25 three eccentric multi-level butt welding butterfly valves are suitable for regulating flow and cutting off fluid on medium pipelines such as metallurgy, power, petrochemical, air, and water supply and drainage with medium temperature s65C. They have reliable sealing performance and are an extension and development of butterfly valves to the medium pressure and medium high temperature fields.