RELINEEUROPE and Rohrsanierung Jensen recently set what is claimed to be a new standard with the rehabilitation of a sewage pipe stretching over 1.1 km along the River Elbe in Hamburg, Germany.
The spectacular projects in Hamburg’s lively St. Pauli quarter are not all at street level. Beneath this quarter in the Hamburg-Mitte borough, a steel pipe of 1,600 mm diameter runs underground. Some sections are up to 80 years old and the wall thickness had been reduced by abrasion and corrosion over the years. Weakened and exposed to static forces, some deformation of the pipe had already occurred. After close investigation, the pipe was therefore no longer deemed stable.
Structural load-bearing capacity a crucial requirement
One of the key requirements of the rehabilitation was to avoid reducing the pipe’s hydraulic capacity while reinforcing it structurally. This significantly limited the cost-effective rehabilitation options. The city of Hamburg therefore opted for rehabilitation with a UV light-curing GRP liner, even though this technology had not yet been used for such a comparatively large project. The part of the old steel pipe in need of rehabilitation measured 1,133 m in length with a diameter of DN1600.
For the installation, the total length was divided into eight rehabilitation sections with individual lengths of up to 230 m. RELINEEUROPE’s Alphaliner1800H product was used for the lining work. This liner can be produced for diameters up to DN1900 and has some of the highest mechanical properties of any CIPP liner in the world. Thanks to its outstanding mechanical load-bearing capacity, the hose liner can be used in projects particularly with very high structural requirements that additionally necessitate/involve high wall thicknesses. In combination with the UV equipment produced by RELINEEUROPE, liners with walls up to 30 mm thick can be cured using UV light.
RELINEEUROPE produced the eight liners in total, one after the other, at its headquarter factory in Rohrbach and delivered them to the Hamburg site on a ‘just-in-time’ basis. Having completed the expansion of its production building and facilities at the turn of the year, RELINEEUROPE was in a position for the first time to produce Alphaliners of up to 600 m in length and weighing up to 70 metric tons. The heaviest liner for the Hamburg project measured 230 m in length and weighed an enormous 45.5 metric tons, making it the heaviest GRP hose liner to date. Together with the reinforced transport box produced specifically for this project, the record- breaking liner reached an impressive gross weight of 52 metric tons. For the first time, two 300 metric ton cranes had to be ordered to load it onto the heavy-duty transporter.
Curing The Liners
All eight Alphaliners had a wall thickness of 20.5 mm and weighed approximately 200 kg/m. As curing such a high wall thickness in the course of this extensive project was a particular challenge, the decision was taken to opt for combination curing. Thanks to a peroxide additive, the resin used would react not only to the UV-light but also to the process heat released during the light-curing process. In order to achieve the best possible outcome during the curing, RELINEEUROPE’s REE4000 UV curing system was used. This offers a maximum output of 24,000 watts in combination with the Power Cube UV core. The automatically extendable UV-light core with a lamp output of 6 x 4,000 watts is specifically designed for curing the largest hose liners. All-important parameters for the curing process, such as pressure, temperature, curing speed and the actual output of all individual UV lamps used, were carefully documented in a curing report. Thanks to the ideal coordination of the Alphaliner and REE4000, curing speeds of up to 1.2 m/minute were achieved.
Not only did the test of the Alphaliner’s material properties meet all expectations, giving the rehabilitated pipe a new service life of up to 70 years, but Hamburg Wasser was also more than satisfied. Although the rehabilitation works had originally been scheduled to last eight weeks, it only took half the time expected. In spite of the disruption caused by the onset of winter, all eight Alphaliners were installed on schedule by contractor Rohrsanierung Jensen within four weeks. In addition to a great deal of experience and professionalism, a very close and cooperative partnership among all involved is key to ensuring the high-efficiency execution of such rehabilitation projects.