Patent ID: 6058978
Filing Date: 2000-05-09
Classification: B29C,F16L,Y10S

Abstract:
A method for relining an existing pipeline, comprising the steps of:deforming a lining pipe having a cylindrical shape to produce a deformed pipe having a deformed shape with a reduced diameter, said deforming step comprising heating said lining pipe to a first temperature at which said lining pipe can be deformed without removing the circular memory of said lining pipe, such that said deformed pipe will return to said cylindrical shape;inserting said deformed pipe into the existing pipeline;heating said deformed pipe to a second temperature above said first temperature while applying an internal pressure, such that said deformed pipe expands beyond said cylindrical shape; andcooling said lining pipe to a third temperature below said first temperature while maintaining said internal pressure to set said lining pipe;wherein only variations in temperature while maintaining said internal pressure are used to reform, expand and set said lining pipe.