Managing ageing and corroding pipes to prevent life threatening leaks and explosions is a top priority for the gas industry and the Health and Safety Executive as well as Ofgem, the government regulator for the gas and electricity markets.

To tackle the issue, it has been mandated that all iron gas mains pipes that fall within 30 metres of a property must be replaced by the end of 2032.

Energy giant National Grid is responsible for around 50 per cent of the UK’s gas distribution network and has been working with contractors Balfour Beatty and TRIIO to replace these at risk pipes. This labour intensive and disruptive process involves placing a new polyethylene pipe inside the existing cast iron host and then making gas tight connections between the replaced mains pipes and smaller service pipes that feed properties.

Currently, these connections can only be made by excavating the pipes and manually connecting them using a process known as electro-fusion. Typically, this involves more than 20 excavations for every 80 metres of mains pipe – a process that is not only costly and time-consuming, but can result in complaints from customers.

Ofgem is challenging network owners to develop and utilise innovative methods to carry out this work to minimise the impact on both customers and the environment.

Now an innovative gas pipe refurbishment solution developed using 3M resin technologies is being trialled by National Grid and Balfour Beatty to make the process quicker and less disruptive to households and road users.

Said senior technical manager from the UK and Ireland Project Management Office, Malcolm Butler: “Cast iron pipes are brittle and prone to degrading as they get older. Our solution involves spraying a specially formulated resin inside the pipe that cures and sets to form a new gas-tight pipe.

“This offers a much quicker and more cost effective solution and causes significantly less disruption as fewer excavations are needed, both on private property and on the road.”

The Pipe Replacement in Situ Manufacturing (PRISM) solution utilises Scotchkote rapid setting polymeric lining resins developed by 3M to recondition water pipes rather than replacing them.

Explained Malcolm: “For the gas pipe application we formulated two resins, one for main pipes and one for the service pipes, under the Scotchkote brand. We also developed a conformable adhesive sleeve that is inserted using a remote controlled robot where the pipes meet. The sleeve creates a continuous pipe surface that forms an unbroken resin lining once it is sprayed.

“For the service pipes, a complementary technology, Blown Air Extrusion, applies a resin using a patented air vortex system that injects the mixed resin into a carefully controlled air flow. This carries the product quickly down the pipe, depositing the fast-curing resin evenly to the dry wall of the pipe, travelling around corners where necessary and up to 20 metres from the point of application.”

The PRISM solution is in the process of being rigorously tested using real, but disused, gas pipe systems, with excellent results so far. It is expected that the 3M solution will start to be used by National Grid in live situations from April 2017.

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