Underground pipe lining procedure uses plastic tube that can be reduced in diameter for insertion in pipe and then expanded to fill it

摘要

A procedure consists of forming a plastic tube that can adopt a first stable state in which its external diameter is smaller than the internal diameter of the pipe to be lined and a second stable state where its external diameter is at least equal to the internal diameter of the pipe. The procedure consists of forming a plastic tube (7) that can adopt a first stable state in which its external diameter (d7) is smaller than the internal diameter (D1) of the pipe to be lined and a second stable state where its external diameter (D7) is at least equal to the internal diameter of the pipe. The tube is inserted into the pipe to be lined in its first state and then expanded inside it by a pressure fluid into its second stable state, pressing against the pipe's inner wall. The lining tube is made by extruding the plastic material in a diameter (D7) corresponding to its second stable state, cooling it and then applying a mechanical force with by means of a lubricated reducing cone to reduce its diameter so it corresponds to the first stable state.