For this procedure, a thermomechanically deformed PE-HD pipe (a modified PVC-U version is also available or waste water application) is pulled into the existing pipeline. Deforming reduces the cross section of approx. 30% compared to the initial pipe.
The pipes are delivered to the site on drums and pulled into the existing pipes by a winch. The flexibility is increased by the deforming process and the smaller cross-section allows the pipe to be introduced via existing access shafts, or in the event of pressure pipes via small installation pits. Depending on the nominal dimensions several hundred meters of pipe can be wound on a drum and pulled in. After installation the factory-deformed pipe is pressure and steam treated and regaining its original shape (memory effect).
The new pipe is now close-fit to the inner wall of the existing pipe. The cross-section is only slightly reduced (twice the wall thickness of the liner pipe). Depending on static-related requirements, the liners are generally manufactured in various wall thicknesses.
Fields of application:
- Suitable for pressurized and non-pressurized pipelines
- Drinking and waste water, gas and industrial applications possible
- DN 100 - 400 mm (one manufacturer supplies pipes up to DN 500 mm)
- Circular profile
- Material: PE-HD, also in modified PVC-U material for non-prezurised pipelines
- Lateral connection mostly in the cut-and cover construction method or with specific welding suitable cap profiles for PE-HD liners for waste water applications
- Calibration of old pipes required
Advantages:
- Short construction time
- No remaining annular space; no filling required
- Introduction can be via existing shafts or in the event of pressure pipes via relatively small trenches
- Shafts without curved channels can be passed through
- Insignificant cross-section reduction (twice the wall thickness of the liner pipe)
- Factory-manufactured pipes with defined material properties
- Long unwelded length or plug connections possible
- The liner is hydraulically very smooth and resistant against aggressive waste water and mechanical
Disadvantages:
- Risk of incomplete recovery (folding) of the new pipe - particularly in the event of position deviation, drifts and nominal dimensions tolerances in the old pipe;
- Not suitable for damage such as position deviation and pipe collapse
