Flexible wedge gate valve

Abstract

A wedge gate valve having a valve body defining a valve chamber and flow passages and upwardly diverging circular seat surfaces of circular, flat configuration and defining seat planes. A valve disk or wedge having downwardly converging sealing surfaces is movable within said valve chamber between open and closed positions for controlling flow through the valve. Pressure boundary plates connected by hubs to the valve disk define the sealing surfaces of the disk and have bottom corners that establish line contact with the downstream seat surface and prevent any portion of said sealing surfaces of said valve disk from crossing the sealing plane of the downstream seat in the event of flow responsive downstream movement of the valve disk during its opening and closing movement. Guide ears of the disk are provided with flexible upper and lower extremities and rounded or chamfered inner end surfaces to minimize localized peak contact stress with disk guide rails of the valve body. The center section of the disk is rendered flexible by the provision of an internal transverse cavity that extends completely through the center section or is located centrally of the center section to define flexible walls between the hubs to thus provide for disk flexibility for overcoming the tendency for disk binding. A valve actuator for opening and closing the valve disk is provided with an adjustable downstop to prevent overtravel of the disk during seating.