National Grid takes on long installation

National Grid has installed a 4.9 km tunnel for a new gas pipeline under the River Humber, England.

The tunnel – which will now transport up to 25 per cent of the UK’s gas supply – will replace an old gas pipeline in the River Humber bed that was at risk of exposure.

Replacing the gas pipeline and pushing the pipe into the new tunnel of this length will become a world record, making this a key project for National Grid and its project partners, A.hak, Porr and Skanska.

National Grid Lead Project Manager Steve Ellison says some of the major challenges the project has encountered include the complicated ground conditions.

“We’ve had to work tirelessly and put some real, good engineering solutions to ensure the safety, and arrival of Mary, our tunnel boring machine (TBM),” said Mr Ellison.

“So we’re really pleased, to be able to engineer a solution to enable this to happen.”

The 160 m, 3,500 mm diameter TBM will now be dismantled and transferred back to Germany to be refurbished for future projects.

In early 2020, two hydraulic thrust machines will push eight 610 m, 850 t sections of pipe on rollers into the new tunnel from the Goxhill side. 

The pipes will be pushed at about 1 m per minute into the tunnel, which will have been flooded with water to aid installation.

When one pipe section has been installed, the next will be moved into position, welded to the one in front, and the push will continue until all 5 km of pipeline is installed beneath the river. 

Upon completion, it will be the longest hydraulically inserted pipe in the world – a feat of engineering for National Grid and its project partners.

For more information visit the National Grid website.

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