Method and means for sealing leaking pipes

Claim 1

A METHOD OF INTERNALLY LINING UNDERGROUND PIPES AND THE LIKE OF EXTENSIVE LENGTH, SAID METHOD COMPRISING THE STEPS OF INSERTING INTO SUCH PIPE A LENGTH OF PLASTIC TUBING OF A TYPE WHICH, UPON APPLICATION OF HEAT THERETO, EXPANDS DIAMETRICALLY TO A DEGREE SUCH THAT IT PRESSES FIRMLY AGAINST THE INSIDE SURFACE OF THE PIPE AND CONTINUES TO SO PRESS AGAINST THE PIPE AFTER AGAIN COOLING, THEREAFTER HEATING SAID TUBING ALONG A LIMITED PORTION OF ITS LENGTH SO THAT ONLY SAID LIMITED PORTION EXPANDS DIAMETRICALLY TO PRESS AGAINST AND BE ANCHORED TO SAID PIPE AND SO THAT ONLY SAID LIMITED PORTION OF SAID TUBING UNDERGOES CORRESPONDING LONGITUDINAL CONTRACTIONS, THE LONGITUDINAL MOVEMENT OF SAID TUBING WHICH ACCOMPANIES SAID LONGITUDINAL CONTRACTION BEING THUS LARGELY LIMITED TO THE UNEXPANDED PORTIONS THEREOF, AND THEN SUCCESSIVELY SO HEATING ADJACENT LIMITED LENGTH PORTIONS OF SAID TUBING TO CAUSE DIAMETRICAL EXPANSION THEREOF, WHEREBY THE RESULTING LONGITUDINAL CONTRACTION ALONG THE LENGTH OF SAID TUBING IS LARGLY LIMITED TO ITS UNEXPANDED REGIONS.