Abstract: A method producing deformed pipe liners from continuously extruded thermoplastic material by collapsing and bending deformable portions of the tube toward a back-up portion thereof and without elongation to maintain diameter and wall thickness, and apparatus to carry out said method and characterized by at least one back-up roller and at least one shaping roller folding the deformable portion along a line of symmetry and juxtaposing a fold of the tube to the back-up portion, all at raised temperature followed by reduced temperature on a rail conforming to the deformed tube configuration.

Abstract: A method is provided for lining a pipe wherein a thermoplastic liner is initially formed in a cylindrical shape with a diameter slightly larger than the internal diameter of the pipe. The liner is temporarily deformed at an elevated temperature to a different cross-section, preferably U-shaped, to reduce its overall cross-sectional dimension to facilitate insertion into the pipe to be lined. The deformation occurs with substantially comparable elongation of the pipe lining along its opposite sides thereby precluding variations in wall thickness and stress in the pipe. Once inserted, the liner is pressurized and reheated first to a temperature below its crystallization temperature to round the lining in the pipe and subsequently, further pressurized and reheated to a second temperature higher than the crystallization temperature to cause the liner to retain its original round shape.

Abstract: Apparatus is provided for lining a pipe wherein a thermoplastic liner is initially formed in a cylindrical shape with a diameter slightly larger than the internal diameter of the pipe. The liner is temporarily deformed at an elevated temperature to a different cross-section, preferably U-shaped, to reduce its overall cross-sectional dimension to facilitate insertion into the pipe to be lined. The deformation occurs with substantially comparable elongation of the pipe lining along its opposite sides thereby precluding variations in wall thickness and stress in the pipe. Once inserted, the liner is pressurized and reheated first to a temperature below its crystallization temperature to round the lining in the pipe and subsequently, further pressurized and reheated to a second temperature higher than the crystallization temperature to cause the liner to retain its original round shape.

Abstract: Method is provided for lining a pipe wherein a thermoplastic liner is initially formed in a cylindrical shape with a diameter slightly larger than the internal diameter of the pipe. The liner is temporarily deformed at an elevated temperature to a different cross-section, preferably U-shaped, to reduce its overall cross-sectional dimension to facilitate insertion into the pipe to be lined. Once inserted, the pipe liner is reheated to the crystallization temperature of the thermoplastic material to cause the liner to return to its original cylindrical shape. Pressure within the liner is also increased in two stages to cause the liner to conform to the interior surface of the pipe. An expansion pig may also be employed to ensure even more exact conformance. After expansion, ends of the liner which extend beyond the pipe are flared into engagement with the pipe flanges. Service fluid under pressure is introduced into the liner to maintain the liner in its cylindrical shape.

Abstract: A method producing deformed pipe liners from continuously extruded thermoplastic material by collapsing and bending deformable portions of the tube toward a back-up portion thereof and without elongation to maintain diameter and wall thickness, and apparatus to carry out said method and characterized by at least one back-up roller and at least one shaping roller folding the deformable portion along a line of symmetry and juxt posing a fold of the tube to the back-up portion, all at raised temperature followed by reduced temperature on a rail conforming to the deformed tube configuration.