CO2 Corrosion Study of Carbon Steel in Natural and Induced Film Forming Environment
Carbon dioxide (CO2) corrosion prediction is complicated as it affects the application of carbon steel material due to possibility of high corrosion rate and the formation of protective iron carbonate (FeCO3) film layers. The formation of FeCO3 film layers is observed to reduce corrosion rate partic...
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| Format: | Final Year Project |
| Language: | English |
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UNIVERSITI TEKNOLOGI PETRONAS
2009
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| Online Access: | http://utpedia.utp.edu.my/4012/1/Dissertation_Report.pdf http://utpedia.utp.edu.my/4012/ |
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| Summary: | Carbon dioxide (CO2) corrosion prediction is complicated as it affects the application of carbon steel material due to possibility of high corrosion rate and the formation of protective iron carbonate (FeCO3) film layers. The formation of FeCO3 film layers is observed to reduce corrosion rate particularly at high temperature and high pH. Most of the FeCO3 film formation studies were done by inducing film formation through the addition of Fe2+ ions into the test solution to reach saturation condition where the product of Fe2+ and CO32- exceeds the solubility product limit and not in natural film condition. This project aims to understand the FeCO3 film formation by conducting laboratory experiment of CO2 corrosion on carbon steel in natural and induced film forming environment with Fe2+concentration (cFe2+) of 50 ppm. The study is conducted at various temperatures from 25°C to 80°C at pH 6.0, partial pressure of CO2 at 1 bar and stagnant conditions to observe how these parameters affect the CO2 corrosion rate and formation of FeCO3 film layers. Two electrochemical test techniques namely Electrochemical Impedance Spectroscopy (EIS) and Linear Polarization Resistance (LPR) are used. EIS technique shows that as the temperature increases the average corrosion rate increases while for LPR technique, the average corrosion rate increases at temperature of 25°C until 60°C before decreases at temperature of 80°C with lower average corrosion rate in induced film forming environment. It is observed that the average corrosion rate is relatively lower in induced film forming environment since the increase of Fe2+concentration results in faster formation of FeCO3 film layers. Based on the results of the corrosion tests in both conditions, it shows that for corrosion prediction work, the test is best represented by natural film forming environment. Induced film condition is only suitable for the study in relations to film initiation, growth and propagation. |
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