Abstract

Resilient stoppers are temporarily compressed and are inserted into tubular conduits and then released to expand therein to stop fluid leakage therefrom. Tapered stoppers larger across than tubes to be plugged are inserted by a tapered hollow tool having a large end to receive a stopper and a smaller end inserted within a tubular conduit to be plugged. Application of pressure to the base of the stopper to force it through the tapered tool also compresses it to a temporarily lesser size. Upon leaving the tool end inside the tube, the stopper expands into non-slipping contact with the surrounding wall. Continued pressure, rather than sliding the stopper in the tube, backs the tool end away and out therefrom, leaving the stopper plugging the tube. Stopper embodiments may have one or more tapered portions, or one or more circumferential recesses into which resilient rings fit, and optionally are adapted to lengthen to receive such rings, and to shorten to compress them longitudinally and thereby expand them circumferentially as may be desired.