Abstract: A method for internally lining ducts and sleeves for ducts lined in accordance with this method are provided. The inner lining sleeve is formed in the duct by the action of a uniform pressure on the inner face of a second sleeve in a form of a sheet made from a sealed synthetic material whose outer face is provided with fibers. This pressure acts so as to enlarge the section of this sleeve by plastic deformation of said sheet and to apply the sleeve against the inner face of a first sleeve made from a composite material permeable over the whole of its thickness and coated with a heat hardenable resin. The section of said first sleeve enlarges without the composite material undergoing elastic or plastic deformation. The two joined sleeves continue to enlarge their sections until the outer face of the first sleeve is applied firmly against the inner face of an envelope in the form of a sheet of sealed synthetic material.

Abstract: An internal lining for ducts (C) is provided by introducing into one end of the duct an assembly (E) which comprises a sleeve (5) and an inflatable system (2) and which is provided with heating means for applying a sheath (1) impregnated with a resin against the inner wall of said duct (C). After partial polymerization at least of the resin, the sheath (1) adheres to the inner wall of the duct. The system (2) is then deflated, the heating stopped and the assembly (E) withdrawn from the duct. With the length of the duct a multiple of the length (l) of an assembly (E), the operation is repeated by introducing into the duct successively a multiplicity of sheaths (1) until the inner wall of the duct (C) is provided with an internal lining over the whole of its length.

Abstract: Process for internally lining a conduit by bonding with a resin to the inner wall of the conduit, of a fluidtight inner lining sleeve under the urging of at least one pressurized fluid acting on the inner wall of the sleeve through an inflatable envelope. The temperature in the envelope required for polymerization of the resin, and the pressure inside the inflated envelope may be controlled.