Abstract: An apparatus for plugging a pressure piping system includes one or more segments that may be positioned in the system to hold a plug therein. Each segment is held in position by a holding assembly including a plunger slideably mounted within the apparatus and actuable to move the segments to a position for engaging and locking the plug in place. A pin or similar member may be employed to affix the segment to the plunger, and an actuator is threadably mounted within the apparatus and used to adjust the position of the plunger. In the preferred embodiment, the actuator is coupled to the plunger by a threaded stud, with the threads of the actuator and of the stud being cut in opposite directions. The stud threadably engages the plunger such that rotation of the actuator activates the plunger toward and away from the segment.