The Development of Corrosion Monitoring Technique on the Coating of Offshore Wind Turbines

Corrosion is always accompanied by disaster in Taiwan because of the high temperature, high humidity, and high salinity environment. To protect metal from corroding in this severe environment, paint coatings are commonly applied on the surface of metal to enhance its corrosion resistance. In order to monitor the health and effectiveness of the coating in the corrosive environment, ElectraWatch Coating Health Monitor (CHM) is employed in the investigation of the corrosion characteristics of coating in this paper. First of all, we compare the data between CHM and Potentiostat Gamry Ref600 to confirm the accuracy of CHM. Then, we test the sensitivity, the limit of impedance at low frequency, and remote transmission ability about CHM. Finally, we focus on the limit of impedance at low frequency and remote transmission ability to make improvements. We design a circuit board to increase the measurement range of impedance. Then, we design the experiment to test the ability of Circuit Test System about its accuracy, limit of measurement, and corrosion monitoring. From the first part of experiment, we discover the accuracy of CHM is consistency with Potentiostat, but CHM has poor ability to test the change of the impedance when the coating is little defect. Moreover, in the test of commercial coating, CHM can’t measure the impedance of the coating because the impedance exceed 108 ohms, the limit of CHM. We also test the measurement range about CHM, and we find its measurement range is apart from electrode type only 30 millimeters. Finally, we test about the remote transmission distance of CHM, and we find that the remote transmission distance of CHM is about 20 meters From the second part of experiment, we discover the accuracy of Circuit Test System is also consistency with Potentiostat. In addition, the measurement limit on testing the impedance of the Circuit Test System is higher than 1010 ohms. Finally, from the experiment of the corrosion monitoring test, we find Circuit Test System can accurately test the change of impedance when the coating begin to emerge defect. We can use Circuit Test System to solve the problem of CHM about testing limit when we need to monitor the corrosion of the coating of offshore turbines. In the future, we will develop the equipment and improve the ability of the remote transmission distance.