A visual demonstration of a Thaxton high pressure, hydrostatic test plug in action. Standard pipe test plugs are factory tested up to 3,000 PSI depending on size. Test plugs are inserted in the pipe and held in place by the steel grips which grab against the inside wall of the pipe when the nut is tightened. At that same time, a neoprene seal cup is compressed and expanded to make a tight seal. A safety gag can be installed after the test plug is in place. The clamp is tightened around the pipe, with the bull ring located loosely over the stem. Pressure is slowly increased and held for the amount of time to test. Once testing is complete, pressure is released from the piping and drained.