Methods and apparatus for sealing an aperture that provides fluid communication between a second and first chamber of a dual chamber orifice fitting. A sealing assembly comprises a closure member that is rotatably moveable between an open and closed position relative to the aperture. A secondary seal is disposed within a recessed portion on a sealing face of the closure member. The recessed portion has a perimeter defined by a shoulder. A primary seal is disposed within a groove formed between the shoulder and the secondary seal.
