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.

This DVGW worksheet shows the revision and extension to the standard approved DVGW G 478 worksheet concerning the water application area. It determines requirements, quality assurance and tests for procedural practice in line with quality. Likewise, the requirements for the material used, i.e. woven fabric liner as well as its combination with the pipe wall, are determined in the DVGW worksheet W 330 entitled Pasted woven fabric liner for water pipes. According to this state-of-the-art, woven fabric relining is regarded as a burst-proof rehabilitation procedure. The existing pipe will be lined holohedrally and sealed against exfiltration with a non-aging woven fabric liner. Corresponding to DVGW test basis VP 404, it is proven through 10,000 hours of creep testing that a bridging of corrosion damage in pipe diameters of up to 2-inch has a life span of at least 50 years. An overview of the possible fields of application for woven fabric relining based on the aforementioned DVGW worksheets is provided in table 1.

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Fig. 5
Small pit for high-pressure water cleaning with mobile hose reel and rotating nozzle with 22,500 psi (1,500 bar) (View from pit 2 towards pit 3)

Fig. 6
See article header.

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Fig. 7
Small target pit of section one.

Procedural application, recommissioning
March 21: Due to the local conditions and existing fittings, a total of five pits were dug and two sections for the woven fabric liner reversion with lengths of 721 feet and 994 feet respectively were designated (Fig. 3). Therefore, the layout of the pits was in such a way that apart from the pit in the area of the burst pipe, no further sports fields were taken up or spoiled by cleaning and inspection equipment. All prepared work has finished. The inner cleaning (Fig. 4) of the pipe is followed by high-pressure water cleaning (Fig. 5) and subsequent partial sandblasting.

The result was checked and documented by camera inspection. The diameter of the woven fabric liner to be constructed and the necessary reversion pressure were determined by bore-measuring. An economic implementation was achieved through use of a special inspection and bore-measuring system for tracks lengths of up to a maximum of 3,000 feet.