A wellhead module, comprising: a housing, a valve member, an actuator assembly, and a locking mechanism. The valve member extends through an opening at an end of the housing and is translatable between an open position and a closed position. The actuator assembly is disposed within the housing and is configured to translate the valve member between the open position and the closed position. The locking mechanism is convertible from a first state to a second state, the actuator assembly is axially locked to the housing at a first axial position in the first state, and the actuator assembly is unlocked from the housing in a second state and thus movable to a second axial position within the housing.