Flexible plastic tubing

Claim 1

A RELATIVELY THIN WALLED, HIGH STRENGTH FLEXIBLE TUBING COMPRISED OF RELATIVELY NON-ELASTIC PLASTIC MATERIAL AND BEING FORMED FROM A SPIRALLY WOUND STRIP OF SAID MATERIAL, SAID STRIP HAVING LATERALLY DISPOSED RELATIVELY THIN FLANGES AND AN INTERMEDIATE CONTINUOUS CENTRAL EXTERIOR RIB OF SUBSTANTIAL RADIAL DIMENSION AND WHEREIN SAID RIB EXTENDS SPIRALLY AROUND THE EXTERIOR OF SAID TUBING, AND WITH SAID FLANGES IN ANY ONE CONVOLUTION OF SAID STRIP BEING SECURED IN LAPPED RELATION WITH THE FLANGES OF THE ADJACENT CONVOLUTIONS OF THE SPIRALLY WOUND STRIP OF MATERIAL TO FORM THICKENED INTERMEDIATE WALL PORTIONS DISPOSED BETWEEN THE RIB PORTIONS AND DEFINING WITH SAID RIB PORTIONS THE ENCLOSING WALL STRUCTURE OF THE TUBING, THE WIDTH OF EACH OF THE FLANGES OF THE STRIP MATERIAL BEING IN THE GENERAL RANGE OF 1.3 TO 2 TIMES THE MAXIMUM WIDTH OF SAID RIB OF THE STRIP OF MATERIAL, THE OUTER EDGES OF EACH OF SAID FLANGES BEING DISPOSED IN AXIAL SPACED RELATION TO THE RIB PORTION OF THE ADJACENT CONVOLUTION, TO SUCH EXTENT THAT THE DISTANCE BETWEEN THE CENTERS OF ADJACENT RIB PORTIONS OF ADJACENT CONVOLUTIONS OF THE TUBING IS IN THE RANGE OF 1.7 TO 2 TIMES THE WIDTH OF ONE OF SAID FLANGES, THEREBY PROVIDING EACH INTERMEDIATE WALL PORTION WITH A PLURALITY OF HELICALLY EXTENDING SECTIONS OF A LESSER WALL THICKNESS THAN THE WALL THICKNESS OF THE REMAINDER OF THE RESPECTIVE INTERMEDIATE WALL PORTION, SAID LESSER WALL THICKNESS SECTIONS BEING OF SUFFICIENT DIMENSION IN A DIRECTION AXIALLY OF THE TUBING TO ADAPT SAID LESSER WALL THICKNESS SECTIONS TO BE FOLDED INWARDLY UPON BENDING OF SAID TUBING TO PROVIDE FOR FLEXURE OF THE LATTER.