Abstract: A wrapped conduit and method of forming it are described in which a layer of hot applied cold flowable waterproofing material of nonuniform thickness is flowed onto a conduit, and over said layer is spirally wrapped under tension a sheet of a nonwoven permeable randomly arranged heat-resistant thermoplastic fibers. An outer or shielding wrap of asbestos felt, plastic film, kraft paper, or the like, is also employed. The product thus obtained has a waterproof layer of essentially uniform thickness which impregnates the sheet of aforesaid fibers.

Abstract: Outer wrap for pipelines is made of essentially flat thermoplastic fibers preferably woven in a basket weave pattern with from about 15 to 20 per cent of the fabric area being open. On wrapping a pipe freshly coated with coal tar or equivalent material, the wrap does not tend to sink into the coating as is found to be the case with other outer wraps, such as those made from round glass fibers. Because of the ability of the mesh wrap of this invention to eliminate air entrapment during the wrapping operation, an essentially holiday-free coating results. This system also lends itself to uniform distribution of cathodic current over the entire surface. The tough, smooth wrapping does not allow cold flow of coating material through the fabric due to the weight of backfill and tension of the wrap.