Temperature effect on cathodic protection (CP) design current density was examined by electrochemical tests, and a case study of optimized CP design for the FPSO (Floating Production Storage and Offloading) using a computational analysis tool was performed. Electrochemical test results showed the specimen (EH36) in 28 °C had the lower current density and higher resistance than that of 5 °C. It was because of calcareous deposit which was verified by surface analysis using SEM and EDS. Computational analysis results showed that the structure in 5 °C didn't satisfy the CP criteria at the bottom shell and mooring chain. The structure at 28 °C satisfied the protective potential range, however, unstable enough to predict corrosion damage. To optimize and resolve the problems, the CP design was changed. Consequently, the structure at 5 °C is sufficient to satisfy the protective potential criteria at bottom shell and mooring chain. In the case of 28 °C, a more even potential distribution is achieved.


Increasing energy consumption leads to building a large number of offshore platforms, pipelines, ships, and underwater storage. These steel structures are exposed to seawater in various environments from tropical to arctic climatic regions, so the corrosion deterioration has to be significantly concerned. In this reason, recently, the importance of cathodic protection (CP) which is one of the protection methods against corrosion is being gradually highlighted with a demand for long lasting design life of offshore structure in the various environments.

Cathodic protection (CP) has been used as a primary method to control the corrosion of metal in conjunction with organic coating. It can reduce corrosion rate, and a properly maintained system will provide protection in accordance with the designed life of the structure. Currently, the importance of CP is being gradually highlighted with a demand for longer lasting design life of offshore structures so that the long-term electrochemical performance of CP becomes a key concern to ensure structural integrity. There are two basic types of CP systems: impressed current CP (ICCP) and sacrificial anode CP (SACP). The ICCP system has a power supply (rectifier), which is used to generate larger potential differences between anode and structure, permitting more current to flow to the structure being protected. In the SACP system, the anodes have more negative potential than the protected structure. When they are connected in seawater, the galvanic current flows from the anode (relatively negative potential) to the protective structure (relatively positive potential) in a DC circuit. They do not require an outside power source to operate, so sacrificial anodes have few limited in their use. Generally, the offshore structure is designed to prevent corrosion by sacrificial anode.

This content is only available via PDF.
You can access this article if you purchase or spend a download.