Abstract: A repair of a butterfly valve having metal seat includes de-watering of the valve, and movement of the disc to the open position. As in the prior art, the extant (usually brass) valve seat is machine in situ and capped with a stainless steel substitute seat having relatively low slope in the range of 10.degree. to 20.degree. with respect to the closing valve disc. The valve disc edge and valve disc edge caps are removed. A new valve flap seal clamp and relatively hard rubber seal (in the range of 70.+-.5 shore) is inserted. The new valve seal edge clamp has a profile to completely capture the inserted rubber valve seal edge and assure that all elastic extrusion occurs only to and toward the refurbished valve seat. This elastic extrusion necks down and decreases in cross-section toward the edge of the disc of the valve. When the clamp is compressed, the elastic section of the rubber valve seal is extruded to extend to and toward the valve seat.

Abstract: A butterfly valve construction for use particularly on pipelines through which fluid under pressure is adapted to flow and to be selectively cut off. The butterfly valve disc is rotatably supported within the valve casing. Within the valve casing at a region whereat the valve disc is adapted to be turned for closing an elastomeric ring is supported and a plurality of clamp ring segments are supported about the casing periphery to abut one face of the elastomeric ring. Each clamp segment is adjustable to a fixed selective position by positively acting means to compress the elastomeric ring against an internal surface of the disc, thereby also extending the ring in a direction toward the valve disc edge when the latter is in a closed position. This extension is adequate to force the elastomeric ring to fit tightly to the valve ring at valve closing times and directly form a tight seal thereto.