Pipe Bursting in Norway
November 22, 2011

The pipeline, originally installed in the late 1960s, showed definite signs of wear. Leaks caused by corrosion requiring elaborate repairs were re-occuring all the time. To assure the water supply for the city it was about time to renew the 40-year-old pipeline. In doing so, it was absolutely necessary to maintain the pipe’s cross section. Due to the corrosive soil conditions a HD-PE pipe OD 710 x 52,2 mm (with coating) was chosen as the new pipe.

For this project, only the pipe bursting method was applicable. Just the right job for contractor Sandum AS from Geithus near Oslo. The civil engineering company won tender due to its long year experience, its know-how and the superior technical equipment. Costs were calculated with 12,000 crowns per meter for open trenching and only 8,000 crowns per meter for the trenchless renewal. These savings of more than 30 percent made the deal perfect.

The pipe bursting project started with a test section, with an option to continue the project. “Big guns” had to be brought up for this mammoth task. A GRUNDOBURST 2500G with 250-t pulling force and a special roller blade for cutting the ductile cast iron pipe was applied. An upsizing head Ø 830 mm was used to displace the split old pipe into the surrounding soil.
The test went well without any imperfection and the replacement of further sections of the pipeline could begin.

The roller blade and expander head were attached to the bursting rods, which had been pushed through the old pipe in advance. When being pulled back, the old pipe is cut and the new pipe is pulled into the expanded void using bentonite to reduce the casing friction at the same time. The tensile load affecting the new pipe was constantly monitored and logged with the GRUNDOLOG measuring device. An average tensile load of 500 kN was measured, which is way below the permissible limit.
The total replacement project was successfully completed within four months, ending in August to the client’s satisfaction.
This article was submitted by TRACTO-TECHNIK GmbH & Co. KG, based in Lennestadt, Germany.