A gate valve including a valve housing defining a valve chamber having an opening therethrough along a flow path, a gate support supported within the valve housing between a closed position in the flow path, an open position outside of the flow path, and a service position extending out of the valve housing, and a dual actuator assembly having a service piston assembly having a service piston reciprocable within the valve housing, and an inner piston assembly having an inner piston reciprocable within the service piston assembly. The gate support is configured to reciprocate with the inner piston between the closed and open positions, and with the service piston between the closed and the service positions. A method of using the gate valve is also disclosed.