Pipe wrapping

Claim 1

IN COMBINATION, A CONDUIT, A COVERING FOR SAID CONDUIT COMPRISING AN ELONGATED FLEXIBLE SHEET-LIKE CARRIER BOARD OF A STRONG ABRASION-RESISTANT HEAT-INSULATING MATERIAL, AN ELONGATED FLEXIBLE SYNTHETIC RESINOUS PLASTIC FILM COEXTENSIVE WITH AND PERMANENTLY BONDED INSURFACE-TOSURFACE RELATION TO ONE SIDE OF SAID CARRIER BOARD TO PROVIDE AN ELONGATED COMPOSITE WRAPPER CONSISTING ONLY OF SAID CARRIER BOARD AND PLASTIC FILM AND SUFFICIENTLY FLEXIBLE TO BE READILY WOUND ABOUT THE CONDUIT, SAID FILM EXTENDING LATERIALLY OUTWARDLY BEYOND ONE LONGITUDINAL EDGE OF SAID CARRIER BOARD TO PROVIDE A CONTINUOUS PLASTIC LAP SURFACE, SAID COMPOSITE WRAPPER BEING WOUND HELICALLY ABOUT SAID CONDUIT WITH THE PASTIC FILM TOWARD SAID CONDUIT AND WITH A LEAD SUCH THAT THE LAP SURFFAC EOF THE UNDERLYING CONVOLUTION IS OVERLAPPED AND SEALINGLY ENGAGED BY THE INNER SURFACE OF THE PLASTIC FILM OF THE OVERLAPPING CONVOLUTION IN A CONTINUOUS OVERLAP JOINT, THE PLASTIC FILM OF SAID HELICAL COMPOSITE WRAPPER PROVIDING A DIELECTRIC MOISTURE PROOF, CONTINOUS INNER PLASTIC BARRIER WHICH IS RESISTANT TO SOIL CHEMICALS AND BACTERIA AND IS COMPLETELY SEALED AT SAID CONTINUOUS OVERLAP JOINT, THE CARRIER BOARD OF SAID HELICAL COMPOSITE WRAPPER PROVIDING AN OUTER COVER FOR SAID PLASTIC FILM PROTECTING THE SAME AGAINST MECHANICAL DAMAGE, SAID CARRIER BOARD PREVENTING SAID PLASTIC FILM FROM SHRINKING BY REASON OF ITS HEAT-INSULATING CHARACTER AND BY REASON OF ITS BEING BONDED IN SURFACE-TO-SURFACE RELATION TO SAID PLASTIC FILM.