N-Sea, the Inspection, Maintenance and Repair (IMR) specialist, has utilised the world’s first wet repair habitat to complete an in-situ subsea cable repair.
The habitat was developed by Moyle Interconnector as part of the seabed repair project, with ESB International the owner’s engineer for the project. The habitat allows repairs to be implemented in-situ below sea level, as opposed to the conventional method of recovering the subsea cable prior to repair.
The diving scope was performed as part of a Moyle Interconnector project to carry out the repair on the Moyle Interconnector cable, a 500MW HVDC electrical interconnector, in the Irish Sea.
The interconnector cable links the electricity grids of Northern Ireland and Great Britain through submarine cables running between converter stations at Ballycronan More in Islandmagee, County Antrim and Auchencrosh in Ayrshire. The fault area was located approximately 2.5km from the Scottish coast and submerged between one and three metres below the seabed, in approximately 25 metres of water.
Explaining the technology and design behind the product, CEO, Gerard Keser, says: “The principle employed by ESB International is based on an incubator design which surrounds the cable section whilst providing a dry and conditioned repair option. We deployed our TUP Diving System® (Transfer Under Pressure) along with one of our subsea support vessels, the Siem N-Sea, which allowed the cable to be repaired in its current position.”
According to the company, N-Sea’s TUP Diving System®, a closed bell diving system, was key to the project, providing safer operations and longer bottom times in comparison to other surface supplied diving techniques. Due to the efficient work process, this diving scope was completed within one month.
Keser adds: “We are proud to have been involved in this innovative project which truly showcases the capabilities of N-Sea and our products. We continually strive to spot and deploy pioneering technology for our clients in the offshore subsea industry, and are delighted that we have provided an efficient and effective solution for subsea repair challenges.”