Diamond Wire Cutting Makes the CUT with DP1 Jacket, North Sea

As part of the Frigg DP1 Jacket removal project in the North Sea, Saipem UK (Sonsub Division) awarded a major contract to Cutting Underwater Technologies (CUT).

The contract is to carry out several Diamond Wire Cuts on the jacket before the pieces are lifted to the surface by a crane and taken onshore for recycling.

CUT will use its innovative Diamond Wire Cutting Machines to sever jacket members, trusses and jacket legs for removal. The DWCM's will cut along horizontal and vertical planes, along with angled cuts to ensure that the cut sections do not "bind" when they are lifted to the surface. Tecnospamec's specially designed Launch Runner Cutting Tool will be used along with the standard DWCMs, which have cutting capabilities of 36, 50, 64 and 74 inches.

"The versatility of the Tecnospamec design, and their in-house engineering expertise, allows CUT to offer exact solutions to any particular requirement that the client may have," Duncan Griffiths, CUT sales and marketing manager, commented. "This allows specialist contractors, such as Saipem to develop innovative solutions to their decommissioning strategies that save both time and money whilst minimizing any environmental impact that the removal operation may incur."

While competing for the contract, CUT performed a number of trial cuts on a mock-up of the DP1 Jacket. During the trial, the DWCM cut through hardwood blocks, rectangular steel sections and a circular section that represented the actual jacket leg. The same diamond wire was used to cut all the different materials and sections.

"Not only did this test validate the effectiveness of our Diamond Wire Cutting Technology," CUT's General Manager Dino Vallarino said, "it reinforced the fact that Diamond Wire Cutting offers the reassurance that once the wire has passed through the target, there can be no doubt that the piece has indeed been severed. This is especially important when cut sections are to be removed by crane to ensure that no excess loads are placed on the hoist components during lifting operations."

Damaged during installation in the 1970s, the 10,000 ton, 8-legged DP1 Jacket has stood on the seabed for more than 30 years while the Total-operated Frigg gas field was in operation.

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