The DT373 worm gear-to-clamp type elastomeric hard seal butterfly valve uses a "U" stainless steel seal ring with a precision elastomeric seal in three-dimensional eccentric contact with the polished butterfly plate. It solves the drawback of sliding contact friction on the sealing surface of the traditional eccentric butterfly valve at the moment of opening and closing 0 ° ~ 10 °, and realizes the effect of separating the sealing surface of the butterfly plate at the moment of opening and sealing when the contact is closed, so as to achieve the purpose of extending the service life and the best sealing performance. Therefore, it is widely used in pipelines of metallurgy, electric power, petroleum, chemical, air, gas, combustible gas and water supply and drainage and other corrosive media with a medium temperature of ≤ 550 °C, and is the best device for adjusting the flow rate and cutting off the fluid.