The close-fit method using pre-deformed PE pipes is a highly efficient and cost-effective solution for rehabilitating old drinking water lines. Thanks to the trenchless construction method, high durability, and improved hydraulic properties, it offers a future-proofed alternative to replacing old pipes and contributes significantly to the sustainability of the supply.
The maintenance and renewal of existing drinking water lines presents many utilities with major challenges. In addition to cost considerations, environmental factors, operational interruptions, compliance with hygiene standards, and structural constraints play an essential role. An innovative and sustainable method for rehabilitating existing lines is the close-fit method using pre-deformed polyethylene pipes (PE pipes). This method enables cost-efficient, trenchless rehabilitation and significantly extends the service life of the pipe network. The newly installed pipe does not merely represent a repair, but is equivalent to a new installation with a corresponding expected service life of over 100 years.
How the close-fit method works
In the close-fit method, a pre-deformed, folded PE pipe with reduced diameter is pulled into the existing pipeline. The original shape is then restored using steam pressure, causing the new pipe to fit tightly against the inner wall of the old pipe (close-fit). The process comprises several steps:
1. Preparation of the existing line:
- Cleaning of the old drinking water pipe to remove deposits and corrosion residues.
- Inspection of the old pipe to assess
structural integrity.
2. Installation of the pre-deformed PE pipe:
- The new PE pipe is initially manufactured round at the factory and then pre-deformed in a special production process so that it has a smaller cross-section.
- Due to the reduced size, it can be pulled into the old pipe over longer distances with minimal resistance.
3. Expansion using steam pressure or hot water:
- After installation, the pipe is returned to its original round shape through controlled heating with steam or hot water.
- The new PE pipe fits tightly against the inner wall of the old pipe and forms a structural, tight, and statically self-supporting inner lining.
4. Cooling and pressure testing:
- After complete expansion, the new pipe cools down. It is then both seamless and load-bearing, making it equivalent to a new pipe.
- Finally, a pressure test is performed to ensure the tightness of all connections and fittings.
The close-fit method is particularly suitable for:
- Drinking water and gas lines in urban and industrial areas
- Wastewater lines with critical infrastructure where conventional rehabilitation measures would be problematic
- Areas with high traffic volumes where open construction would cause significant disruptions
Performing such close-fit rehabilitation requires specialized contractors. Two partners of our company introduce themselves briefly below:
Diringer and Scheidel
DIRINGER & SCHEIDEL DRUCKROHRTECHNIK offers innovative solutions for the trenchless rehabilitation of pressure pipelines. The traditional company employs all common, certified rehabilitation methods, including close-fit lining.
In this area, the company relies on quality products from egeplast. Through decades of accumulated expertise, DIRINGER & SCHEIDEL DRUCKROHRTECHNIK can also offer customized solutions from a single source. This ensures high cost-effectiveness and shortened construction times while conserving resources.
PRS
PRS Rohrsanierung GmbH is a company of the PREUSS Group. Utilities and industrial companies have relied on the proven competence and performance of the PREUSS Group for over 20 years when it comes to the construction, modernization, and operation of infrastructure and facilities. With close-fit lining, PRS offers an optimal liner rehabilitation method with which pressure pipelines in particular can be renewed to the highest quality in a sustainable and environmentally friendly manner. Water means life – drinking water pipelines require special care. Experts must also be deployed to ensure safety in gas pipelines. You will find them at PRS! You can rely on the expertise of the PRS Rohrsanierung rehabilitation teams.
Advantages of the close-fit method
Trenchless rehabilitation
No extensive road or earthworks, minimizing traffic disruptions and surface disturbances.
Optimized hydraulics
The smooth inner surface of the PE pipe reduces flow resistance, improves flow capacity, and minimizes deposits.
Minimal operational interruption
Due to rapid installation, drinking water supply is maintained in many cases or only briefly interrupted.
High longevity
PE pipes are corrosion-resistant, chemical-resistant, and have a service life of over 100 years.
Sustainability
The method conserves resources, reduces the CO2 footprint, and extends the service life of existing infrastructure without extensive new construction measures. 100% recyclable pipe material.
egeplast
egeLiner®
The pre-shaped egeLiner® is wound onto steel drums, tailored to the length of the section being renovated. This achieves a cross-sectional reduction of up to 40 percent, allowing long construction lengths to be delivered to the site.
Fundamentally, the folded egeLiner® pipe strives to equalize the stresses frozen in its wall and transform back into its round original shape — this is referred to as the reversion process, which causes the return to the original form (“memory effect”). This property makes the close-fit method highly efficient and ensures that, after successful Installation, the egeLiner® adheres closely to the inner wall of the old pipe and can be fully integrated into the existing pipeline network without restriction.
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Source: Sustainability
