N E W S R E L E A S E from FURMANITE NORWAY
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10/08/04
In-situ machining while operation continues avoids downtime for FPSO
Skilled on-site machining by Furmanite Norway has addressed problems of wear on the vital turret-turning system of an FPSO in the North Sea, and enabled modifications to be undertaken to allow future maintenance costs to be cut, all while operation continued as normal, maximising asset uptime.
The turret turning and locking system on the FPSO, situated in the Norwegian sector of the North Sea, has been operational since field installation in 1999 and was showing signs of excessive wear. The turning flange was deformed at the upper and lower edges, due to extreme contact pressures between the guide rollers and the flange. Some failures on the four grippers (the system comprises four deck-mounted jacking cylinders and a gripper unit per cylinder) were also detected.
Machining was required to the upper part of the turning flange to remove a protruding edge and make the top surface flat. However, a number of challenges meant that this was no routine exercise: there was to be no welding or drilling in mounting the machines, and the work was to be undertaken at sea, during full production. The turret turning system is vital to the safe operation of the FPSO, avoiding excessive twisting of risers and mooring lines as the vessel rotates, and 100% availability is required throughout the operational life of the FPSO.
Furmanite, known for its high level in-situ machining expertise, was called in to help, and was able to engineer a solution that met the onerous demands.
Additionally, it was recognised that some "minor" modifications would improve the performance and the system and significantly reduce the future need for repairs, thus cutting anticipated maintenance costs.
To undertake the modifications the grippers and push cylinders had to be dismounted, involving removal of the ΓΈ160 x 400 yoke pins at each end of the cylinders - a task that had proved difficult in previous maintenance operations. Furmanite, however, was able to remove the pins with no structural damage, using a boring and sawing process. The modifications were then successfully accomplished.
The work was completed while production continued uninterrupted - avoiding the need for shutdown and return to dock, thereby representing massive savings.