Cathelco is supplying a hull corrosion protection system for the Cidade de Paraty, an FPSO which is being converted at the Keppel Shipyard in Singapore.
After completion the vessel will be operated in the Tupi Nordeste development off Brazil by SBM Offshore who have signed a twenty year charter and operation agreement with Petrobras.
The FPSO is being converted from the Mt Theseus (265,243 dwt), a VLCC built by Hyundai Heavy Industries in 1988.
The Cathelco impressed current cathodic protection system (ICCP) will protect the entire wetted surface of the 322 metre hull against corrosion. It will consist of a 400amp forward system and an 800 amp aft system.
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 8 ‘diver change’ linear loop anodes and reference cells.
“This vessel will operate for twenty years without drydocking and therefore the Cathelco system has been designed with diver changeable anodes which can be changed at sea, if necessary”, said Aneel Mumtaz, a corrosion engineer at Cathelco.
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.
“We have a considerable amount of experience in designing hull corrosion protection systems for FPSOs and are aware of the factors which need to be taken into consideration such as the drain on the system from mooring chains”, Aneel Mumtaz explained.
This is the fourth time that Cathelco 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. Two years ago, another Cathelco system was installed on the FPSO 57 during conversion at the Keppel yard in Singapore.