the actual lifetime consumption, but also explains possible deviations from design predictions.
Monitas Group AHMS provides not only detailed fatigue estimates, but also extensive databases of operational and environmental conditions. Results and findings of the Bonga FPSO will be analysed in parallel with those of other ongoing hull structure monitoring programmes. Results and analyses are discussed in plenary sessions between all Monitas Group participants. These results can be used in various ways including design verification, inspection planning and life- time extension.
For Bonga, AHMS comprises 12 active sensors, 4 Long Base Strain Gauges on deck and 8 strain gauges in the water ballast tanks. These sensors are located at two cross sections of the vessel at both the portside and starboard side. At each cross section two junction boxes (portside and starboard side) are installed on top of the main deck nearby the water ballast tank where the strain gauges are installed. Power supply is distributed from the AHMS panel to all the junction boxes. From these junction boxes signal cables run to all sensors.
Upon completion of the Factory Acceptance Tests of the AHMS equipment at MARIN, it was shipped to Nigeria. The AHMS panel and junction boxes were installed by the Shell crew aboard, and they also installed and terminated the cabling.
Teamwork vital In June 2016, the Long Base Strain Gauges on deck were installed by MARIN. These sensors were glued on deck to avoid hot work during production and the sensors in the water ballast tanks will be installed in the spring. The main challenges so far have been the installation procedures. Synergies with all teams involved in the installation phase were vital to manage the operational exigencies.
Past and future findings regarding the accuracy of lifetime predictions for FPSOs are of paramount importance. Through systematic and dedicated monitoring equipment and coherent analysis, hull integrity can be visualised for the personnel onboard, as well as for naval architects in the office. The structural performance of the Bonga FPSO will be examined and compared to its peers, extending MARIN’s and the Monitas Group participants’ knowledge on fatigue loads and overall lifetime assessment.
The Monitas Group project, which starts a new three-year phase in 2018, is still open for new participants.
SInstallation of Long Base Strain Gauge on deck
AHMS installation team report 23
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