A method for in-situ fabrication of a bi-layer composite pipe by feeding a compression-fit, shape memory polymer inner pipe into a host pipe, the method comprising the steps of:
- providing an inner pipe comprised of a shape memory polymer which exhibits the ability to return from a deformed shape to an original shape induced by an external stimulus;
- feeding the shape memory polymer inner pipe to a pipe tensioner mechanism which pulls a tail end of the inner pipe rearward while simultaneously pushing the inner pipe forward at a constant velocity to a deformation tool mechanism and then into the host pipe, with no pull tension being used to drag the inner pipe to the deformation tool mechanism, the inner pipe being fed at constant velocity to the deformation tool mechanism;
- the deformation tool mechanism being comprised of a plurality of stations of orifice forge rings of mechanically variable diameter, each of the orifice forge rings having a parabolic curvature, each forge ring having an entry and an exit, the exit of one forge ring being separated sufficiently apart from the entrance to a next successive forge ring so as to develop pipe wall axial compression in the wall of the inner pipe, resulting in recoverable radial wall thickening rather than axial elongation and wall thinning between successive forge rings;
- pulling the shape memory polymer inner pipe forward with a pulling mechanism while holding the inner pipe in axial tension sufficient to inhibit diameter memory recovery of the shape memory polymer inner pipe and to overcome drag friction of the inner pipe at axial tension loads low enough to minimize axial creep elongation of the inner pipe undergoing insertion;
- monitoring the pulling force of the pulling head and winch on the shape memory polymer inner pipe with a load feedback controller to thereby provide a controlled tension differential that prevents premature memory recovery of the shape memory polymer inner pipe;
- discontinuing pulling of the inner pipe once the inner pipe is fully inserted within the host pipe and allowing the shape memory polymer inner pipe to recover memory and be mechanically seated and locked by compressive friction within the host pipe.