Insulated pipe assembly

Claim 1

In an insulated pipe construction, a pipe, a layer of insulating material formed about said pipe, a barrier layer laid about the outside of said insulating layer, said barrier layer including an outer layer of felted, porous mat constructed of many intertwined and intermingled strands randomly oriented and interspersed so that said mat possesses many small, randomly oriented, and interconnected interstices, an inner layer of plastic material characterized by being impervious to the penetration of an incompletely cured second material or water, said inner layer being applied to said outer layer as an incompletely set plastic liquid so that said outer layer as an incompletely set plastic liquid so that said inner layer interpenetrates a partial thickness of the outer layer and flows into the interstices within said outer thickness to form an interconnected pliable mass throughout the available volume therein, the remaining thickness of said outer layer remaining available as a porous volume, an outer casing protective plastic formed and applied as an incompletely cured liquid polymeric formulation about said barrier layer and cured in situ thereon, said polymeric formulation being of such a character that it interpenetrates the available remaining thickness of said outer layer and flows into the remaining interstices to form an interconnected solid mass therein to the interface of the inner layer, said inner layer and casing together forming an integral structure with said outer layer, said structure characterized by complete mechanical interlocking of the plastic of the casing and inner layer into each partial thickness in which each plastic forms interconnected branches throughout the respective volume of the interstices.