InterMoor, a brand in Acteon’s Moorings and Anchors business line, was contracted by a major North Sea operator to provide project management, planning and offshore support for planned maintenance on its floating production storage and offloading (FPSO) vessel. The maintenance on the FPSO, involved the replacement of the winch wire, the top chain replacement on three mooring lines and post-recovery testing of the recovered chains to assess their condition.
THE CHALLENGE
Each of the three key scopes of the project presented several unique challenges that needed detailed planning and engineering during offshore and onshore execution.
Winch wire replacement
Due to restricted space and handling constraints on the FPSO, the replacement of the mooring winch wire was completed by transferring the wire between an anchor handling vessel (AHV) and the FPSO. Although this method avoided any heavy machinery on board the FPSO, it involved transferring the wire from the geostationary part of the FPSO turret, through fixed structures on the rotational part of the hull and transfer to and from the assisting AHV. The complexity of the transfer presented challenges due to the tight tolerances required for the line routing and coordination between the vessels including the control of the catenary line to achieve required back tensions.
