A tube testing system consists of two subassemblies, the probe and the applicator. The probe uses a stack of Belleville style washers that when compressed allow the locking fingers to relax and the probe to be inserted into the tube. Once the probe is placed in the correct location using the applicator, the Belleville style washers are allowed to expand, locking in the fingers and engaging the urethane seals. As the water fills the tube, the air is pushed through a bleed hole in the mandrel of the probe. The bleed hole leads to a chamber in the top of the probe that contains a plastic ball. The ball floats on water and as the chamber fills, the ball seals off the leak path and the tube can then be pressurized and the test performed. Once the test is complete, the water is drained and using the applicator, the probe is removed from the tube.