Method of making hose construction

Claim 1

In a method of making a hose construction for conveying fluids having nonpolar hydrocarbons comprising the step of providing a seamless tube of a polyolefin material and of indefinite length, and treating the inner surface of said tube with a fluorine gas to define a barrier layer having a fluorocarbon composition as an integral portion of said tube, said barrier layer rendering said tube substantially impermeable to said hydrocarbons, the improvement comprising the steps of disposing an inert treating gas inside said tube as said tube is being extruded from a mass of said material through a tube forming die means so that the inner surface of said tube is maintained oxygen free at the time of forming thereof, sealing a leading end portion of said tube to prevent loss of said treating gas, winding the treated tube to define a first supply roll thereof, cutting said tube between a pair of sealing clamps after extruding a predetermined length thereof thereby sealing both the trailing end of said tube wound on said first supply roll and a leading end of said tube to be wound on another supply roll, forcing said fluorine gas through said trailing end of said tube while in said first supply roll thereof to displace said inert treating gas and to treat said inner surface thereof while the same is still oxygen free, and, thereafter, purging said fluorine gas from said tube while still in said first supply roll thereof by forcing a purging gas through said trailing end thereof.