Mitigating SF6-emissions: Performance evaluation of external adhesives as leakage mitigation in simulated and field conditions

Through market research and supplier engagement, several potential sealing products were identified. Products were evaluated on criteria such as safety, reliability, durability, flexibility, speed, applicability, shelf life, and cost. Five promising main products and one auxiliary product were selected for further testing in the laboratory. During phase 2, the main products and the auxiliary product were tested in various combinations and conditions on an in-house developed steel test compartment. Artificial leaks were created on steel test compartments, and products were tested for their ability to seal under increasing pressure (up to 800 kPa absolute

(abs). The key findings of phase 2:

 After full curing, metal composites and fast-drying epoxy achieved the best performance in pressure tests.  For overpressure applications, products with the shortest curing times were most successful.  All products were removable with minimal surface damage, although metal composites adhered more strongly. During phase 3, field tests were carried out on switchgear components at multiple substations where SF₆ leaks had been identified. Out of sixteen leaks, fifteen were successfully sealed, with pressure levels varying from ambient up to 800 kPa abs.

The best all-round product was epoxy with the additional auxiliary product also referred as

“putty”, while fast-curing rubber was most effective for sealing under pressure. Gas quality analyses showed no negative impact from the sealing products on the quality of the SF6.

The project developed a practical methodology for leak sealing, confirming that complex leaks can be addressed without taking equipment out of service (if safely accessible), especially at lower pressures. Long-term monitoring (at least six months) indicated that the seals remained effective and that refilling the compartments was unnecessary.

Complex SF₆ leaks can be sealed quickly and effectively, reducing emissions, costs, and downtime. Further practical experience is recommended to refine the methodology and answer remaining questions about long-term performance and gas quality impacts. The program provides a practical, tested approach on reducing SF₆ emissions in the Dutch electricity grid, supporting climate goals and operational efficiency. The methodology and product selection can serve as a framework for other network operators facing similar challenges.