Process for installing a new pipe inside an existing pipeline

A method of lining an existing pipeline with a substantially rigid thermoplastic pipe comprising the steps of:

• manufacturing a substantially rigid, thermoplastic pipe in a flattened and folded shape in at least a length comparable to the length of an existing pipeline to be lined;
• said flattened and folded thermoplastic pipe having cross-sectional dimensions less than the cross-sectional dimensions of the lumen of the existing pipeline to be lined to facilitate insertion of the flattened and folded pipe into the existing pipeline;
• storing the flattened and folded pipe on storage means in a layered condition to facilitate transport of the flattened and folded pipe to an installation site;
• heating the flattened and folded pipe at the installation site while the pipe remains in the flattened and folded shape;
• removing the heated, flattened and folded pipe from the storage means;
• said heating of said pipe being sufficient to render said pipe softened and deformable to facilitate extending of the pipe from the storage means to a substantially elongated condition for insertion into the existing pipeline and to enable subsequent expanding of the pipe from the flattened and folded shape;
• feeding the heated, elongated pipe through the lumen of the existing pipeline while it remains flattened and folded;
• positioning the heated, elongated, flattened and folded pipe within the lumen of the existing pipeline;
• heating the pipe, now positioned inside of the existing pipeline, the pipe remaining in its flattened and folded shape;
• applying internal pressure to the pipe positioned inside the existing pipeline thereby expanding the heated pipe from the flattened and folded shape to cross-sectional dimensions comparable to the cross-sectional dimensions of the existing pipeline;
• ceasing to apply heat to the pipe to allow the pipe to cool and again become substantially rigid thereby allowing the pipe to maintain its expanded shape;
• and,
• ceasing to apply internal pressure to the expanded substantially rigid thermoplastic pipe in place within the existing pipeline;
• said expanded, substantially rigid pipe being capable of withstanding hydrostatic and earth pressures.