HOBAS® - and the Heat Is On: Relining Cooling Pipes in Bremen, Germany

Special about this new power plant is that the use of the fossil fuel can be reduced considerably by using so-called medium-caloric fuels to generate power and heat. This fuel consists of a mixture of paper, plastic, wood and packaging materials. Until 2005, residual material like this was stored at waste dumps as it was unsuitable for recycling. Other than black coal, it primarily consists of renewable raw materials yet generates a similar heating value. Thus, the operator of the power plants, Bremen’s public utility, is able to save over 90,000 tonnes of coal and reduce the environmentally harmful CO2-emission by around 230.000 tonnes.

In summer 2008, corrosion was discovered on a cooling water pipe in the heating power plant. This asked for immediate repair under strict safety conditions, without restricting the energy production and without endangering the construction schedule of the new plant.

An open trench construction was not an option as the line crosses a coal storage area which would have had to be removed with tremendous effort. Under the given conditions, relining with HOBAS Pipes proved to be the ideal solution. The old steel line was rehabilitated by the company Michel Bau GmbH & Co. KG utilizing 180 m HOBAS CC-GRP Pressure Pipes HOBAS CC-GRP Pipe DN 1200, PN 6 with a wall thickness of only 27 mm. The thin walls and excellent hydraulic properties of HOBAS Pipes resulted in absolutely no loss in flow rate despite the reduced diameter compared to the old steel line. In addition to the 180 meter long straight section, two 20 m long curved branches DN 900 that merge into the larger cross-section were installed by open trench. Once more, the broad range of HOBAS Fittings, that is easily adapted to individual customer requirements, proved to be highly advantageous. The final pressure test was completed successfully and on the first attempt. Bremen’s public utility was very satisfied with the result, particularly with the fast and simple installation of HOBAS Pipes and the professional project support by HOBAS experts.