Two hydraulic thrust machines began the epic task of carefully pushing eight 620m long sections into a pre-bored tunnel from Goxhill side of the Humber on 23 June.
Each 850 tonne pipe section was steadily pushed at around one metre per minute into the tunnel, which had been flooded with 50,000 cu m 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.
Project partners Skanska, A.Hak and Porr built the 3.65m diameter tunnel 30m under the river to replace a trench-laid gas pipe which had become exposed.
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.
“Our customer, National Grid, set us a considerable challenge; in fact a “world’s first” challenge and our team has risen to it brilliantly.”While 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.”
When gas begins to flow through the pipeline towards the end of this year, it will help ensure a reliable and resilient supply of up to 25% of Britain’s gas.
Steve Ellison, Senior Project Manager, Capital Delivery, for National Grid, said: “We will now begin work to connect the pipeline to the network, ready for gas to begin flowing towards the end of the year.”