TPi October 2009

after installation. One opening was made in the upper area of the old pipe both in the starting construction pit and in the destination construction pit. These openings allowed the remaining water quantity that was unable to be discharged by the existing drainage facilities to be pumped off. High-pressure cleaning was then carried out immediately, with simultaneous extraction and transportation away of the sludge residue. The solid incrustations left behind were removed by mechanical cleaning. Calibration then provided a ‘surprise’ – unlike the specifications in all planning documents, the old pipe in the repair section was not DN 1,050, as assumed, but was only DN 1,000. In order to able to use the PE 100 pipes already on site, it was necessary to implement a more major reduction. The technical parameters were recalculated. The high flexibility of the Simona PE 100 pipe allowed the work to continue within tolerance with no interruption. Calibration with 985mm diameter followed by a concluding camera inspection ensured that the old pipe had been adequately prepared for the pull-in operation. The counter-bearing structures required in the starting construction pit and destination construction pit were allowed for as early as digging the construction pits.

Figure 2 ▼ ▼ : Hot-tool butt welding is used to join the two pipe trains tension-proof with one another

The swagelining process met all these requirements. A great deal of positive experience with preceding constructionprojects done by LudwigPfeiffer documents the reliability of this repair process. The swagelining process The swagelining process is a cost-effective process for the repair of discharge pipes comprising standard PE 100 pipes without permanent annulus. It is one of the reduction processes in accordance with DVGW W 320. In the case of the swagelining process a long pipe train comprising several Simona PE 100 pipes is prefabricated on the construction site. The outer diameter of the PE 100 pipe, at 1,060mm, is larger than the inside diameter of the old pipe in order to guarantee a durable Close-Fit position after installation. The cross-section is reduced by tensile force and compressive force for the duration of pipe pull-in. The new pipe is pulled in with a pulling device on-site by a reduction tool. The pipe remains constantly subject to tensile stress during the pull-in process. Consequently, it can be interrupted at any time, eg in order to connect individual pipe trains before the pipe pull-in operation. When the final position is reached, the tensile force is reduced, thus increasing the outer diameter again. The result is a perfect Close-Fit. The new Simona PE 100 pipe tightly follows the course of the old pipe. One major advantage of this process is that time-intensive preliminary work, such as cleaning the old pipe and welding the individual pipe trains, can be carried out in parallel in the construction process. Preparatory measures Various types of preparatory work were required so that the new pipe could be easily pulled into the old pipe and so that a Close-Fit position in the old pipe was reached

Figure 3 ▲ ▲ : The 500m long pipe train was moved without difficulty to the starting pit using lightweight equipment

Figure 4 ▲ ▲ : The complete pipe train was pulled into the existing pipe in a single pulling operation

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October 2009 Tube Products International