Jumbo Offshore Handles Riser Caisson for Technip FMC

Jumbo Offshore, part of the Netherlands-based Jumbo Group, has called into action its Fairplayer heavy-lift crane vessel to carry out the transport and wet storage of a 120-metre-long riser caisson for oil services specialist Technip FMC.

The Fairplayer picked up the riser caisson, a component commonly used in offshore foundations, from the Port of Nigg in the Scottish Highlands. The ship’s two 900-tonne capacity mast cranes used double slings and five connection points to handle the highly-flexible unit.

The caisson was then transported to the offshore location for wet storage – the most challenging phase of the project, said Jumbo’s project manager Carol Granneman. Wet storage is a technique often used in offshore operations whereby structures are temporarily kept on the seabed.

“Due to the motions of the waves and the buoyancy of the caisson, the most critical moment was when we lowered the caisson through the splash zone,” Granneman said. “Then we had to lower it evenly through the water column to avoid excessive stresses in the caisson.”

Once set on the seabed, Jumbo used a remotely operated vehicle, or ROV, to disconnect the caisson, leaving two rigging points in place to allow Technip FMC to pick it up for installation at a later date.

“This job involved the careful handling of fragile offshore equipment,” Granneman said.

“But with our experienced crews and engineering teams, combined with the dual cranes of the Fairplayer, Jumbo Offshore had the technical capabilities and offshore expertise that made this precision operation a success. Technip FMC is a very valued client of ours and we look forward to working with their team in the future.”