Study On Failure Behavior And Life Of Epoxy Oil-resistance Conducting Coatings

With the rapid development of China's national economy,energy consumption is increasing day after day. In primary energy consumption,crude oil accounts for 23% to 24%. Tanks are essential facilities used for transportation, storage and security operation of these crude oil, but there are corrosive impurities in crude oil,and they would damage the tank.In order to control the occurrence of corrosion accident of these storage tanks,a variety of corrosion technology are developed at home and abroad. Anti-corrosion coating,which accounts for 63%,is the most important technical measures for corrosion protective of the tank. So the coating property is important for oil tanks protecting.At present, the performance evaluation of coating in tank maintenance can only rely on past experience to judge, so it has big security risk. Therefore, scientific and effective evaluation of anti-corrosion coating performance on the tank, can lay a good foundation for improving the corrosion protection system of petrochemical.This paper selected Epoxy Oil-resistance Conducting Coatings,which is used a lot on oil tank of the petrochemical industry.The coatings were immersed in normal temperature and high-temperature (80℃) crude oil seeper, then coatings were tested periodically with Electrochemical Impedance Spectroscopy(EIS) and Infrared Spectroscopy(FTIR).Through these,we studied on failure behavior and protection life of coatings. Specific studies are as follows:Firstly, as immersing time continues,different impedance spectroscopy was measured by EIS testing.According to map features, used Zsimpwin software to determine electrochemical equivalent circuit model at different immersing time,and then studied the whole process of coating failure.Secondly,through the analysis of coating capacitance,resistance and characteristic frequency value by EIS,which are represented failure of coating / metal, to study water transmission in epoxy coating,and coating performance during the immersing time.Thirdly, using FTIR test to find out the main organic groups of coating aging and degradation.According to groups changes to study the whole process of coating aging and degradation. Finally, through coating thickness, coating "needle index" and the Arrhenius Equation three methods, combining with some mathematical means, we proposed made of epoxy coating to protect life prediction of 3 methods for predicting protective life of five layers(200μm) epoxy coating.and got its ptotective life in crude oil seeper is roughly 4 ~ 7 years.