BigPatents India

A flexible tubular article for transport of volatile hydrocarbons permitting only negligible escape of such vapors comprises: (a) a relatively thin, inner layer of an elastomeric form of an FKM fluoropolymer, and (b) one of more relatively thin intermediate layer of a thermoplastic form of an THV fluoropolymer extruded in tubular form over the inner FKM layer, the FKM inner layer and the intermediate THV layers together having a transverse thickness sufficient to present a substantial barrier to volatile hydrocarbon escape, and (c) a durable outer layer of an elastomeric polymer bonded to the outside surface of the intermediate layer and being coextensive therewith. The intermediate layers having increasing amounts of fluorine content and at least on the intermediate layers comprises a THV grade 800. (FIG). 1