UK COMPANY Cutting Underwater Technologies (CUT) has just completed what is described as ground-breaking decommissioning work on North West Hutton, a redundant North Sea platform.
The work was commissioned by Dutch heavy-lift specialist Heerema Marine Contractors and involved CUT using innovative diamond-wire slicing technology to make 77 separate cuts, including those of the BP platform’s massive steel corner legs (120in outside diameter and 2.75in thick), and including 14 grout and vent lines, the structure’s two launch runners’ legs and other jacket structural members.
To accomplish this huge, yet delicate, task 130km (81 miles) north-east of Shetland, the Aberdeen-based company developed new machines and methodologies. CUT used four specialised cutting machines of 10, 18, 30 and 50in cutting capacity, along with the custom-built 60-12in modular unit needed to slice through the legs.
Extensive onshore tests were carried out to assess the efficiency of this new design – and, for example, full-scale mock-ups of key elements such as a section of the 120in corner legs, including all internal piping were made.
This dry-run part of the project was carried out both in the UK and The Netherlands. Only then was the full equipment spread mobilised to the Heerema heavy-lift vessel, Hermod, in mid-March this year.
Cutting Underwater Technologies was formed 10 years ago by Italian parent Tecnospamec, since when the firm has expanded, with bases now established in Norway, the US, Singapore and, most recently, Brazil.