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New Molten Metal Technology For Substation Repairs

image credit: Rawwater repair at Dinorwig
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  • Mar 15, 2023

Anti-leak solution helps to keep UK's National Grid substations in service during SF6 maintenance

A UK-based engineering technology company called Rawwater has created an innovative solution to repair key grid infrastructure, without the need for outages. Sulfur hexafluoride (SF6) is an insulating gas traditionally used in high-voltage electrical equipment to prevent short circuits, ensuring networks are safe and reliable. Unfortunately SF6 is a polluting gas and many organizations, including the National Grid, are pledged to phase it out. It can leak during repairs and this will mean that the substation has to be shut down.

This new technology has been successfully used for repairs at Dinorwig and Sizewell substations, major nodes on the grid network.

Rawwater has worked with National Grid to utilize its 'M3 Molten Metal Manipulation' technology, to seal flowing leaks, which used to require a planned outage. SF6 infrastructure is designed to be effectively sealed, however small leaks can occur as equipment ages – and it often requires an outage for the SF6 gas to be safely extracted, the repairs carried out and the gas container refilled.

The company's novel solution involves the application of a mould to leaking pipework, into which a low-melting point liquid alloy is injected. The seal requires no setting time once solidified, so it can be applied to equipment while it is in service.

After an initial trial at National Grid’s Deeside Center for Innovation, and further studies at Cardiff University, this technology has been successfully implemented onsite at the Dinorwig and Sizewell substations – proving the concept that while leak repairs took place, electricity could continue flowing to the grid from two of the country’s largest hydroelectric and nuclear plants.

Nicola Todd, head of strategy and innovation at National Grid Electricity Transmission, says, “This clever and cutting-edge new technology is helping us reduce SF6 leaks while keeping our critical infrastructure in service, reducing the need for outages. That’s a double benefit for consumers as we reduce environmental impact and keep electricity flowing around the country.”


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