Abstract: A butterfly valve is provided having a disc with a hub. The disc is adapted to be rotated between an open and a closed position. A valve seat is adapted to engage the disc in the closed position. A shaft has one end affixed to the hub and extends outwardly therefrom to permit torque to be transmitted to the disc from a point external thereof. The end of the shaft affixed to the hub includes a plurality of splines for securing the shaft to the hub. Each of the splines interfers with the hub by a maximum dimension of 0.030 inches. The hub has a stress that is less than 20,000 pounds per square inch. The shaft is joined to the disc by forming the valve disc with a portion of increased thickness (hub) relative to the main portion of the disc. The portion of increased thickness is formed adjacent the circumference of the disc. A hole is then machined into the portion of increased thickness parallel to the disc, with the hole having a diameter slightly smaller than the diameter of the shaft.

Abstract: A butterfly valve is provided having a disc adapted to be rotated between an open and a closed position. A valve seat made of resilient material is adapted to engage the disc in the closed position. The valve seat has an outer wall surrounding the disc and has an aperture therein. A shaft has one end affixed to the disc and extends outwardly through the aperture. A ring surrounds the valve seat and is permanently affixed thereto for preventing deformation of the outer wall of the valve seat. The ring is made of a material that is much stronger and more rigid than the valve seat and includes a cylindrical lip defining an aperture in the ring. This aperture is in line with the aperture in the valve seat wall with the lip projecting into the aperture in the valve seat wall. A cylindrical collar surrounds the shaft and is positioned within the cylindrical lip and supported thereby. The collar provides a bearing surface for the shaft.