Abstract: A gate valve including the usual resilient seal around the stem also includes a single metal seal which provides a fluid-tight metal-to-metal seal around the stem when the valve is either in a fully opened or a fully closed position. In a fully closed valve position the resilient seal around the valve stem can be replaced without interfering with the operation of the valve. The metal seal can be used to provide and maintain a fluid-tight seal between the stem, the valve body and the valve bonnet when extreme conditions of temperature, pressure and/or fluid contact where the resilient seal might fail.

Abstract: A manual override control for use with a double-acting hydraulic or electric powered valve actuator provides means for selectively moving the actuator rod between its extended and retracted positions in the event of a failure of the primary actuator control means. The override control includes a generally cylindrical housing having an axial passage throughout its length, means for connecting one end of the passage to an actuator housing, a threaded drive nut rotatably mounted in the other end of the passage, a threaded member having a socket portion at one end thereof for releasably connecting it to an actuator rod, and means for rotating the drive nut to move the threaded member, and thus the actuator rod, in an axial direction. When functional operation of the primary actuator control means is restored, the override control can be quickly disconnected from the actuator rod and/or normal operation of the actuator can be resumed.