Abstract: A gate valve for controlling the flow of pressurized fluid having a dynamically-energized seal between a seat ring and a valve body. The dynamically-energized seal may be located in an annular groove defined in a flange sealing face of the seat ring to seal against an annular shoulder sealing face of the valve body. A plurality of fasteners may bring the flange sealing face of the seat ring to a mechanical stop against the shoulder sealing face of the valve body and dynamically energize the dynamically-energized seal. An obturator may engage and disengage the seat ring to control flow through the gate valve.