SENSFIB Hull Stress Monitoring for FPSOs

The experience gained by Light Structures on ship hull stress monitoring is easily adapted to an FPSO. The system is of a similar technical scope, allowing computation of the FPSO's response to sea and cargo loading. This response can be linked to the ship's motion and the sea state, allowing predictions on a future condition statistics basis. Received data can be continuously logged during the day-to-day field operations as well as under towing to the field.

Of particular interest for FPSOs is the evaluation of fatigue accumulation. By comparing the logged strain (rainflow diagram) to the steel SN-curve, a remaining lifetime estimate (or damage parameter) can be kept continuously up to date. A single sensor in a key position can, through the use of information from the design-phase numerical model, provide a lifetime estimate for a number of different at-risk locations in the vicinity. The detailed loading history and fatigue accumulation is of great value as input to refurbishment and relocation processes.

Our recent FPSO installations include those on OSX Nexus I and Total's Pazflor FPSO.

Mooring Tension Monitoring

The SENSFIB system can be extended with a mooring tension display for moored offshore structures. In addition to the current mooring line tension, the graphical display shows the present positional and bearing offset, as well as key environment parameters.

Mooring tension data can be based on fiber optic sensors from Light Structures AS or signals from an
existing mooring tension monitoring system.