Replacement pipeline will supply up to 25% of Britain’s gas

National Grid says work to replace a vital gas pipeline under the River Humber is almost complete.

Construction of a five km replacement tunnel 30m under the River Humber was finished last year and now, in the penultimate stage of the project, the last piece of gas pipeline has been inserted.

Working with project partners Skanska, A.Hak and Porr, the 3.65m diameter tunnel was built 30m under the river to replace a trench-laid gas pipe which had become exposed.

When gas begins to flow through the pipeline towards the end of this year, it will help ensure reliable and resilient supply of up to 25% of Britain’s gas.

Two hydraulic thrust machines began the task of carefully pushing eight 620m long and 850 tonne sections of pipe on rollers into the new tunnel from Goxhill side of the Humber on 23 June.

The pipes were pushed at around one metre per minute into the tunnel, which had been flooded with 50,000 cubic metres of pure and treated water to aid the installation.

After one pipe section had been installed, the next was moved into position and welded to the one in front. The push continued until all five kilometres of pipeline were fully installed on 9 July, becoming the world’s longest hydraulically inserted pipe.

Steve Ellison, senior project manager, Capital Delivery, for National Grid, said: “Completing the installation of the pipeline under the Humber is a major milestone for both the project team and partners.

“We will now begin work to connect the pipeline to the network, ready for gas to begin flowing towards the end of the year.”

Gregor Craig, CEO of Skanska, said: “This fantastic achievement shows what can be achieved when you put three expert companies together and create a highly collaborative environment.

“I am very proud of this joint venture between Ahak, Porr and Skanska. Our customer, National Grid, set us a considerable challenge; in fact a “world’s first” challenge and our team has risen to it brilliantly.

“Whilst we still have a way to go, it is clear that we are on track to provide National Grid with the critical national infrastructure solution that they were seeking.”