Numerical simulation and re‐design optimization of impressed current cathodic protection for an offshore platform with biofouling in seawater

• Published in: Materials and corrosion 2018-02, Vol.69 (2), p.239-250
• Main Authors: Wang, W., Li, W.‐H., Song, L.‐Y., Fan, W.‐J., Liu, X.‐J., Zheng, H.‐B.
• Format: Article
• Language: English
• Subjects: Anode effect; Anodic protection; Biofouling; biofouling deposits; Calcium oxide; Cathodic protection; Computer simulation; Condition monitoring; corrosion; Corrosion prevention; Corrosion products; Corrosion tests; Design optimization; Finite element method; Legs; Lime; Magnesium oxide; Mathematical analysis; Mathematical models; Offshore drilling rigs; offshore platform; Protective coatings; remotely operated vehicle (ROV); Remotely operated vehicles; Seawater; Simulation; Superconductors (materials)
• ISSN: 0947-5117; 1521-4176
• DOI: 10.1002/maco.201709685

A finite element model (FEM) of the offshore platform with biofouling is developed here to predict the effectiveness of the ICCP under seawater. Remotely operated vehicle (ROV) test verified that the offshore platform was fully covered by a coating‐like biofouling to protect the structures from corrosion. FE‐SEM and EDS tests demonstrated that the biofouling deposits on the offshore platform mainly contained magnesium oxides, biofouling deposits, and corrosion products doped with calcium oxides. The polarization relationships of platform steel with biofouling coverage were used as boundary conditions for the numerical simulation. Furthermore, the factors including output current, anode location, seawater conductivity, and biofouling coverage rate, which influenced the protective effectiveness, were comparatively evaluated by FEM. Then, a re‐design two‐anode ICCP system was employed to keep offshore platform in protective condition. A ROV monitored the potential distributions of the legs and demonstrated that numerical simulation results of ICCP had a good agreement with measured data. A finite element model of the offshore platform with biofouling is established to predict the effectiveness of the ICCP under seawater. The factors including output current, anode location, seawater conductivity, and biofouling coverage rate were comparatively evaluated by FEM. A ROV monitor demonstrated the protective condition of a re‐design offshore platform.