In the heart of Prague’s city center, an old steel pipeline was rehabilitated using egeLiner® technology. Due to the tight space constraints, high installation speed, and the need to avoid traffic disruptions, there is no economically viable alternative to this rehabilitation method for gas pipes. Consequently, Prague Gasworks uses the egeLiner® on a regular basis.
Project description
Rehabilitation of a historic gas pipeline in Prague’s city center near the riverbank
Challenges
- tight timeframe
- limited space constraints
- high traffic volume
Solution
Use of the egeLiner® RC on drums for trenchless pull-in
Project participants
| Client | Prague Gasworks |
| Location | Prague, city center |
| Planning office | Projektová Kancelár ANY |
| Implementation | Installation: Zepris s.r.o. / Ludwig Pfeiffer
Sales partner: Gerex Liberec as sales partner |
| Construction company | Zepris s.r.o. / Ludwig Pfeiffer |
Rehabilitation of a gas pipeline in Prague’s city center
In the course of planned road renovations and the reconstruction of the “Bridge of the Legions” in the city center on the banks of the Vltava in July and August 2020, the DN 500 steel pipe was rehabilitated. The insulation of the old steel pipeline no longer met today’s requirements. By rehabilitating the gas pipeline, Prague Gasworks is ensuring the future operational and supply security for its gas customers. Prague Gasworks has long been one of the most important energy suppliers in the Czech Republic, with a company history dating back to 1847. Today, they reliably supply around 420,000 consumers throughout the Czech Republic with gas and electricity. The project planning was carried out by Ing. Arnost Polak from the engineering office Projektová Kancelář ANY. He has many years of experience.
For operational and supply security
A total of 404 meters of egeLiner® gas pipes made of PE 100-RC, DN 500, SDR 21 were used. The construction site was divided into 6 sectors of 30, 82, 51, 67, 81, and 93 meters. The sections were produced exactly according to the sector lengths, delivered to the construction site wound on drums, and pulled directly into the old pipe by the installer on-site.
Easy pull-in into the old pipe
The investor deliberately chose the egeLiner® as a pre-deformed pipe for close-fit lining due to its special advantages, as the existing pipeline continues to be used in this rehabilitation method. The process is a close-fit technology according to EN ISO 11295. The egeLiner® PE 100-RC is stress-crack resistant and has been used in the gas industry for a long time due to special safety requirements and positive experience. The result of the rehabilitation is a PE 100-RC pipe with the same pressure class as the surrounding steel pipe, which additionally protects the internal PE pipe from potential mechanical damage. The installation was carried out by Zepris s.r.o., a subsidiary of Ludwig Pfeiffer, which specializes in trenchless rehabilitation methods for drinking water, wastewater, and gas pipelines. Many joint projects involving large pipes and special civil engineering have been successfully and professionally carried out by qualified personnel with this important egeplast partner in the Czech Republic. The egeLiner® system was supplied by Gerex Liberec as the exclusive sales partner in the Czech Republic.
Good planning and coordination
Construction work began on June 21, 2020, and commissioning took place as early as August 29, 2020. Installation during the peak tourist season in the center of Prague proceeded according to plan with only minimal traffic disruptions – thanks to good planning and close coordination between the utility, supplier, and construction company. Branislav Ohrablo, site manager at Zepris s.r.o. with many years of experience in the field of close-fit lining, has preferred using egeLiner® pipes in recent years. He says: “We appreciate the reliable transport and delivery of the egeLiner® pipes, the packaging in white foil, and the high-quality fastening on the drums, which allows for unwinding from the drum in several sections. The material is of high quality and behaves ideally in the reversion process. Thank you for the excellent cooperation.”
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.
Learn more
