Offshore cutting solutions provider Decom Engineering deployed its recently launched, ultralight chopsaw, the C1-16UL, to complete a “challenging” deep-water project in the Gulf of Mexico.

The subsea cutting specialist was approached by a major contractor 18 months ahead of its campaign to devise a protocol for cutting a 137-mm-diameter stud-less mooring chain, located in an active field with tight restriction around dropped objects.

The floating production system had been towed into place and connected to the mooring system where it was locked into position with the 137-mm link chain. Three chains on each corner of the platform were then tensioned, leaving 12 loops of loose chain which needed to be cut and removed by Decom.

“We had no doubt our C1-16UL chopsaw was suitable for this project, but the real challenge was in the link retention. We overcame this by developing link retention clamps which allowed the cut links to be tethered back to the other chain links, ensuring they could not fall to the seabed when cut,” says Decom MD Nick McNally.

“The retention clamp system was positioned [using a] remotely operated vehicle (ROV) and tightened with a Class 4 torque tool. The 12 cuts were all completed successfully with the fastest cut being completed in just 15 minutes,” he adds.

The project also needed to be executed on a Jones Act vessel which meant Decom supplied and trained US personnel to operate the tools on deck, while providing 24-hour onshore support during the cutting phase.

The C1-16UL is the latest development in Aberdeen-based Decom's “highly respected” chopsaw range, that is specifically engineered to cut flexible risers and mooring chains under tension, riser turret moorings and deepwater tensioned moorings.

The C1-16UL has also been designed to accommodate multiple deployment methodologies which include Decom’s purpose-built deployment frame, typically used with a subsea basket or, as in the Gulf of Mexico project, attached directly to the front of an ROV.

Weighing about 270 kg, but only 30 kg in seawater, the ultralight chopsaw offers “unprecedented manoeuvrability” with ROVs, while maintaining “robust and efficient cutting capabilities”.

“The versatility of the C1-16UL combined with its lightweight design, [creates] entirely new possibilities for subsea intervention work. A focus of our growth strategy is to secure more projects in North and South America, and this successful campaign is another feather in our cap which strengthens our position as an innovative, trusted and reliable technology partner,” concludes McNally.