Abstract: A valve seat for a butterfly valve having an annular, rigid reinforcement ring embedded in a body of molded elastomeric material. The seat has a pair of diametrically aligned shaft openings for the valve disc supporting and actuating shaft. These holes extend through the elastomeric material and the reinforcement ring and, during molding of the elastomeric material, are occupied by removable cores which center the reinforcement ring about the cores between the end faces of the mold and position it concentrically between the inner and outer circumferential walls of the mold cavity. To prevent the reinforcement ring from rotating about the cores and to center it positively between the end faces of the mold, a pair of aligned pins are provided, one in each of the mold end faces, which clamp the reinforcement ring between them. These pins are located circumferentially along the reinforcement ring approximately halfway between the cores.