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Stakeholder Relations Team

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The north of England’s gas distributor, Northern Gas Networks (NGN), has become the first utility company in the UK to trial the revolutionary Subterra Subline structural close-fit PE pipe lining technology to minimise disruption to local communities caused by mains replacement.

The trial scheme which took place at NGN’s Considerate Constructor Site at Cutsyke Road, Castleford and a gas mains replacement project in Whitehaven, Cumbria, was conducted after NGN worked with Subterra (part of RadiusPLUS) to investigate alternative ways of replacing large diameter cast iron gas mains.

Using this innovative method in Castleford, the overall project duration was shortened by four weeks, causing less disruption for road users and pedestrians on one of the main roads from Castleford to Wakefield.  Over 100 tonnes of environmental waste was also saved at the site, greatly improving efficiency.

Although the technology has been used with solid wall PE pipes in the past, this is the first time that this pipe renovation method has been used with Radius Systems’ ProFuse, a peelable PE pipe.

In Whitehaven’s busy shopping district, the new technique enabled engineers to replace 740 metres of cast iron main with the new polyethylene pipe, without the need to use the traditional open cut method, avoiding lots of potential disruption to customers. The overall project duration was reduced by six weeks.

The Subterra Subline structural lining process involves concentrically reducing the diameter of the new PE pipe by approximately 10%, by squeezing the pipe between sets of rollers. The reduced PE pipe is then inserted into the existing gas main and expanded to its original size by pressurising with cold water to form a close-fit liner.

Following the success of the scheme, NGN is already investigating ways it can work with Subterra to develop the Subline PE pipe lining method across future gas mains projects.

Warren Iveson, construction services area manager at Northern Gas Networks said: “As Cutsyke Road is one of the main roads used in the Castleford area, we wanted to do everything we could to minimise the disruption to members of the public and limit traffic management without having to cut into the carriageway. The Subterra Subline technology was the best solution.

“Working with Subterra to be one of the first gas networks to utilise the new technology has allowed us to not only become more efficient and reduce the project time but to also guarantee future innovation within gas mains replacement technology. We are already looking into further ways that we can use different methods of ‘rolling down’ pipes that can be shared with other utility companies.”

NGN delivers gas to 2.7 million homes and businesses across the North of England and provides the region’s rapid response service for customers who smell gas at home or work.

The company is investing £90 million per year in its gas mains replacement programme which will see around 3,800 km of old metal gas mains replaced by 2021 to ensure the continued, safe and reliable supply of gas to customers for years to come.

For more information go to www.northerngasnetworks.co.uk