Rotary valve with pressure energized seal

Abstract

A rotary valve is provided including a valve element mounted within the flow path of a valve body and rotatable about a stem axis. A peripheral seating surface on the valve body surrounds the flow path through the valve body and is spaced from the stem axis for sealing engagement with the valve element when rotated to its closed position. The peripheral seating surface on the valve body is preferably annular, and more preferably has an arcuate cross-sectional configuration and includes a central annular seating line spaced closer to the center point of the valve than adjoining upstream and downstream portions of the seating surface. The valve element includes a rigid body with a peripheral resilient overlay. The resilient overlay has a peripheral pressure-responsive sealing member for flexing in response to fluid pressure into sealing engagement with the seating surface. A peripheral backup shoulder is provided on the rigid body of the valve element for preventing extrision of the sealing member under high pressure when the valve element is in engagement with the annular seating surface. The concepts of the present invention are particularly well suited for a plug valve and provide reliable sealing engagement between the plug and the seating surface when a high pressure differential exists across the closed valve.