Prague: Rehabilitation of Steel Gas Pipelines with egeLiner®

Relevance of Rehabilitations

Europe faces the challenge of renovating and modernizing its old and often dilapidated gas supply pipelines. This rehabilitation is also of great importance in the context of discussions about a future transition to new gas sources, particularly hydrogen. The egeLiner® technology, where a close-fit polyethylene pipe is installed against the inner wall of existing gas pipelines, offers a straightforward solution for trenchless rehabilitation of steel gas pipelines or pipelines made of other old materials.

Project Implementation

The construction project in the center of Prague, which involved the rehabilitation of steel gas pipelines in the areas of Klárov, Pod Bruskou, Kosárko-vo nábřeží, and surroundings, was implemented in 2022 by the company ZEPRIS s.r.o. The construction site was located near the government seat and in the immediate vicinity of the Vltava River. The DN 500 steel gas pipeline, rehabilitated here over a length of 600 m, is part of the critical infrastructure. For this reason, extensive safety measures were required during the rehabilitation. In addition, the immediate proximity of the gas pipeline to the government seat made precise coordination essential. For this project, there was also a requirement that the backfilling of the excavation pits could only be carried out under the supervision of a fire safety officer for safety reasons.

Rehabilitations in Prague

The installation company ZEPRIS s.r.o. has many years of experience with trenchless technologies and also collaborated with the Design Engineers and the investor in preparing the project documentation. The rehabilitation of gas pipelines in Prague is carefully scheduled for specific months of the year to avoid major disruptions. Design Engineer Arnošt Polák summarizes after the construction phase: “The egeLiner® technology is an excellent way to rehabilitate steel gas pipelines without the need for an open trench. The result is modernized gas pipe systems with a long service life and high reliability. Thanks to the advantage of small excavation pits and high installation speed, this technology minimizes environmental impact in dense cities like Prague. This method for gas pipeline rehabilitation requires careful preparation. But it also offers many advantages and is often the only available solution for trenchless rehabilitation.”

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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.