Abstract: A removable plug for an internally threaded opening has particular application in a system for closing an opening in the sidewall of a pipe. The system includes a nipple having an inner end attached, such as by welding, to a pipe, and an outer end having internal threads. A short length externally threaded cylindrical plug body is threadably positionable within the nipple outer end, the plug body having a recess in a top surface thereof. An insert is affixed within the plug body recess providing an operating space within the recess below the insert, the insert being formed of a metal plate having a tool receiving central opening therethrough and at least one integral tang portion extending downwardly into the plug body operating space, the insert being secured, such as by welding to the plug body. The insert central opening is shaped in a geometrical pattern, such as a square, to slidably and non-rotatably receive a plug engaging portion of a driver of matching cross-sectional configuration.