PE Reduction Method
Refurbishing/installation using the Close Fit method
In rehabilitation of pipes without an annular gap, the PE pipes are inserted into the old pipe in such a way that the outer diameter of the PE pipe is equivalent to the inner diameter of the old pipe, and the new pipe thus contacts tightly with the old pipe, leading to the use of the term “close fit”. For this purpose, the new pipe is either deformed (“squashed”) to an irregular cross-section and restored to its original shape using steam pressure after installation, or the outer diameter of the new pipe is reduced. This procedure is referred to as “swage lining”. The pipe is drawn onto a die matching the inner diameter of the old pipe and kept under tension until the complete pipe string has been installed. When the tension is removed, the pipe reassumes its original shape until the annular gap has been closed and the new pipe contacts closely with the old pipe.