Offshore contractor Allseas has equipped its giant heavy-lift vessel Pioneering Spirit with a second unique lift system capable of removing and installing complete offshore jackets weighing up to 20,000 t in one go.
Allseas said in an update on Wednesday that the installation works of the “Jacket lift system” (JLS) on the Pioneering Spirit lasted several months.
The company added that recent activities had focused on the “hang-off and upend system” (HOUS), the function of which is to raise and tilt the 170-m lifting beams.
As explained by Allseas, the HOUS comprises integrated upend systems, each with a pair of 50-m skid tracks fitted with “push-pull” mechanisms. Hydraulic cylinders drive the push-pull devices along the tracks, moving the beams up, while transom-mounted hang-off frame (HoF) assemblies function as hinges around which the beams rotate.
Allseas emphasised that, while the technology installed on the Pioneering Spirit is ground-breaking, the way the system works is rather simple.
After cuts are made to a jacket’s foundation piles at seabed level, hoisting blocks suspended from the lifting beams raise the jacket at the main legs. The jacket is subsequently aligned with the beams, reclined, and skidded further inboard before transit.
According to Allseas, the jacket lift system will further enhance Pioneering Spirit’s versatility and capability and provide the offshore energy market with a total solution for heavy lift work.
In recent company news, Allseas and its Pioneering Spirit vessel were in January 2021 awarded a contract to remove the DP3 and DP4 platforms from Morecambe Bay off the UK for Spirit Energy.