Cathelco Jotun are supplying their largest ever impressed current cathodic protection (ICCP) system for an FPSO which has been ordered from Single Buoy Moorings (SBM) by Petrobras of Brazil.

The FPSO P57 is a larger unit than any other previously supplied by SBM and will have the capacity to produce 180,000 barrels of oil per day and undertake the compression of 71 million cubic feet of gas per day.

The new vessel will be converted from the Accord, a 255,272 dwt VLCC, at the Keppel Shipyard in Singapore. When delivered at the end of 2010, the spread moored FPSO will be positioned in 4,100ft of water in the Jubarte Field off Brazil.

The Cathelco Jotun ICCP system will protect the entire wetted surface of the 322 metre hull against corrosion. It will consist of a 400amp forward system and a 1,000 amp aft system, making it the most powerful ever supplied for an FPSO.

The forward system will have a thyristor control panel connected to two hull mounted 'diver change' linear loop anodes and reference cells. In the case of the aft system, the arrangement will consist of 6 'diver change' linear loop anodes and reference cells.

"Diver change linear loop anodes are ideally suited to FPSO applications", said Kevin Ward, sales manager of Cathelco Jotun. "They emit a powerful current from a relatively small surface area, so fewer anodes are required. In addition, maintenance is simplified over the entire life of the vessel as the anodes can be changed at any time by a diver". In operation, the reference electrodes measure the electrical potential at the hull/seawater interface and send a signal to the control panel which automatically raises or lowers the output to the anodes. The current emitted by the anodes neutralises corrosive activity on the surface of the hull, ensuring that the optimum level of corrosion protection is achieved throughout the life of the vessel.

This is the third time that Cathelco Jotun has supplied equipment for FPSO conversions ordered by Single Buoy Moorings. In 2005, an ICCP system was supplied for the Capixaba during conversion in Singapore and in 2007 a system was installed on the Espirito Santo.

"We have the technical expertise to design ICCP systems which must operate in rigorous conditions over long periods of time and this is matched by equipment which has been specifically designed to simplify maintenance", Kevin Ward concluded.

Tags: Cathelco Jotun, Petrobras