Integrating inspection data with a CP simulation model enables the creation of a “digital twin” of the structure which can be used to predict the present and future protection provided to all parts of the structure. The design of marine structures is typically based on design guidelines that specify the protection potentials on the structure to be achieved by the CP system and the rate at which elements of the protection system such as coatings are to be assumed to degrade over the life of the structure. As part of the design study, the performance of the CP system can be evaluated and optimised using a CP simulation model which predicts year by year the protection potentials, the depletion of the anodes, and in the case of ICCP the current to be required by the system. While this type of simulation provides valuable information to the design engineer by confirming that the required protection will be achieved. In reality, the actual performance of the CP system will be often different as coatings for example often degrade at different rates to that described in the design rules, environmental conditions may vary, the “as-built” structure may be different and changes and retrofits are made over time. Integrating the CP data collected during the routine inspection surveys with a CP simulation model enables a “digital twin” of the structure to be created by adjusting the model to match the inspection data. In this way, the simulation digital twin represents the behaviour of the structure and the CP system at the time the inspection survey was performed. This then provides the ability to predict the present and future protection for all parts of the structure. By repeating the process with each new inspection report the engineer can easily monitor the differences between the model predictions and survey data systematically to assess current “health” of the structure, identify anomalies, predict and plan for future risks, optimise the inspection strategy and provide early identification of problems which will require actions. In this paper, a case study is presented where the approach is used as part of the integrity management of an FPSO. The paper will describe the system developed and applications of both the 3D corrosion data visualisation and the simulation-based digital twin.
Key words: Corrosion, Corrosion Data Management, Digital Twin, Cathodic Protection