Abstract: A high pressure seal structure to seal against fluid pressure around a cylinder member movably. The structure includes an integral circular metal sealing ring including a pair of first circular sealing lips having a cross-section of chevron shape axially opening in a first direction to flexibly extend with a first inner lip in sealing relation against the cylindrical surface of the cylinder member and with the first outer lip in sealing relation against a cylindrical wall formed in the housing. Also included is a pair of second circular sealing lips having a cross-section of chevron shape axially opening in a second direction to flexibly extend with a second inner lip in sealing relation against the cylindrical surface and with a second outer lip in sealing relation against the cylindrical wall. A deformable inner sealing ring having a triangular cross-section is closely fitted in the space defined by the first inner lip, the second inner lip, and the cylindrical surface.

Abstract: Wellhead flow control valve including a valve body, a hydraulic linear actuator means connected to valve body in alignment with operating chamber. Actuator has Belleville spring return. A seat sleeve carrying a valve seat and an internal lining mounts at outlet of operating chamber. Drive shaft moves flow control member of prescribed configuration into and out of valve seat sleeve. Flow control member and valve seat cause complete flow closure. Hydraulic conduit connects into actuator to admit hydraulic fluid to move piston and to compress spring. Activator is responsive to a pilot signal for: activating a pump control switch; to permit operation of pumps; activating a by-pass valve switch to keep closed a by-pass valve between conduit and sump of pump; and activating a blocking valve switch to keep open a blocking valve connected between pump and actuator.