The Effects Of Applied Potential And Coating Thickness On Cathodic Disbondment Of Polyurea Coating

• Main Author: Abdul Halim bin Razak , Abdul Halim
• Format: Final Year Project
• Language: English
• Published: Universiti Teknologi Petronas 2010
• Subjects: TJ Mechanical engineering and machinery
• Online Access: http://utpedia.utp.edu.my/1471/1/Abdul_Halim_bin_Razak.pdf; http://utpedia.utp.edu.my/1471/

Cathodic disbondment of buried pipelines is a serious threat to the integrity of the corrosion protection system of the pipelines. This project investigates the effects of applied potential and coating thickness to cathodic disbondment of polyurea coating. The objectives of this project are to determine suitable applied potential of cathodic protection and dry film thickness that will not cause cathodic disbondment. The investigation involved two cathodic protection experiments. For the first experiment, four samples with 1.5 mm coating thickness were used and each of them were exposed to different applied potential which varied from -600 mV to -1500 mV. For the second experiment, four samples having 1.0 mm, 1.5 mm, 2.0 mm and 2.5 mm coating thickness were used and the same applied potential of -850 mV were used. Result from the experiments show that at coating thickness of 1.5mm, -850 mV is the best applied potential for cathodic protection that can avoid cathodic disbondment. When -1500 mV applied potential is used, it causes a lot of cathodic disbondment effects. Then, at -850 mV applied potential, 1.5 mm is the optimum coating thickness that can reduce cathodic disbondment effects. When the coating thickness increases more than 1.5 mm, cathodic disbondment effects are also increase. Besides that, absorption of water also increases as the coating thickness increases. In conclusion, an applied potential of -850 mV and a coating thickness of 1.5 mm was found able to reduce cathodic disbondment effects.