In a bid to cut greenhouse gas emissions and improve asset reliability, National Grid is now using a new method to seal leaks of sulphur hexafluoride (SF₆), a potent greenhouse gas used in high-voltage switchgear and circuit breakers. The solution, developed by materials engineering firm Belzona, allows for leak repairs without taking equipment offline.
SF₆ plays a critical role in insulating high-voltage equipment, but aging infrastructure can develop leaks over time. These leaks not only pose environmental concerns but also traditionally require scheduled outages for repair. The new system — known as SF₆-FIX — uses a composite encapsulation method to contain and seal the leak while the equipment remains in service.
Initial trials began in 2022 following a joint evaluation between National Grid and Belzona. Since then, the repair method has been deployed at several substations including Seabank, Stocksbridge, and Tilbury, with further installations expected throughout 2025. Sixteen additional sites were surveyed in 2024 for future applications.
As part of the rollout, National Grid engineers received hands-on training at Belzona’s UK facility earlier this year, ensuring that in-house teams can support the ongoing implementation. Technicians from Belzona have also completed National Grid’s safety and competency training standards, enabling on-site work with minimal disruption.
“This collaboration demonstrates how innovative repair technologies can support the sustainable and efficient operation of power grids,” said Phil Robinson, director of Application and Training at Belzona. “By sealing SF₆ leaks quickly and reliably, we’re helping minimise environmental impact while ensuring the resilience of the UK’s electrical infrastructure.”
National Grid has set a target to cut SF₆ emissions from its transmission network by 50% by 2030, compared to 2018/19 levels. Rob Mills, Commercial and Portfolio manager for SF₆ Emission Abatement at National Grid, emphasized the dual value of the solution: “This means we can keep electricity flowing while reducing environmental impacts — a double benefit for consumers.”
As utilities globally seek ways to reduce emissions from essential infrastructure, low-disruption methods like this one are gaining traction. The success of the early applications could inform future best practices for managing aging SF₆ equipment across the power sector.
