High Performance Fabric In Old Piping: Quick, Durable Restoration Of Operational Safety

By Andreas Hüttemann, Qualified Engineer Director, R&D/Quality Management, Karl Weiss Technologies and Brian Mattson, Business Development Manager, GTI | December 2009 Vol. 64 No. 12
Fig. 6 Woven fabric reversion of pit three toward pit one with a length of 994 feet.

March 24: Reversion of the woven fabric liner takes place in section one. Overall, for the track length of 994 feet, over 2,200 pounds of adhesive are mixed in and filled into the woven fabric liner. The reversion of pit three takes place towards pit one. In this instance, the self-propelled and thus mobile pressure drum proves to be particularly advantageous because an exact positioning in the pit can take place on a platform area. Despite the large working weight of approximately 31,000 pounds, no damage to the surface fastening occurs due to the rubber-reinforced caterpillar chassis. As the diameter of the woven fabric liner is designed for placement within the inner diameter of the pipe to be rehabilitated, a long-term, crease-free liner is achieved despite the high-strength woven fabric. Through the cold, hardening adhesive system with a very long pot life, the thermally induced tensions in the existing pipe which can occur during warm hardening and cause weld seam breaks in bitumen-coated pipes, will be closed. After hardening of the adhesive, the woven fabric liner is holohedrally and permanently stuck to the inner wall of the old existing piping.

March 25: The woven fabric liner reversion of the 721-foot-long section two is being carried out. For this purpose, 1,764 pounds of adhesive is used. Reversion takes place from pit five (Fig. 8 + 9) to pit three.

The pipe is positioned after the carrying out of the pressure test and trenchless opening of hydrant connections in section one with the aid of tiller robots. Once the water test corresponds to the drinking water ordinance.

May 14: The works are completely finished. During construction time, the existing sports fields were able to be used apart from the actual area of pipe damage.

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Fig. 8
Positioning of the self-propelled pressure drum with rubber-reinforced caterpillar chassis at the starting pit (pit five)

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Fig. 9
Pressure drum during hose reversion at the starting pit (pit five) of section two.

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Table 2 List of DVGW rules for trenchless constructions