THE PERFORMANCE COMPARISON OF KETOCONAZOLE AND FLUCONAZOLE AS ORGANIC INHIBITORS ON DECREASING CORROSION RATE OF API 5L GRADE X56M STEEL IN SWEET CORROSION CONDITIONS

• Main Author: Adi Nugraha, Alvin
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/41616
• Institution: Institut Teknologi Bandung

Corrosion in the mild steel is the most common problem in the oil and gas industry due to the low corrosion resistance of mild steel. One of many reasons is the application methods to improve recovery in the oil and gas industry. Secondary recovery method uses injection of HCl and tertiary recovery method uses CO2 gas injection, the combination of this process is called Enhanced Gas Recovery (CO2-EGR). CO2-EGR results the corrosion phenomenon called sweet corrosion. Therefore, the inhibition mechanism of corrosion is needed. Organic inhibitors are chosen because of being environmentally friendly, economical, and able to reduce corrosion rates in various acidic mediums on mild steel surfaces. In this study, two types of organic inhibitors were used, namely: ketoconazole and fluconazole in a mixed medium of 1 M HCl and 1 M Na2CO3 with a volume ratio of HCl: Na2CO3 is 1.8: 1, thus CO2 gas can be formed and obtained the desired initial medium pH. Soaking duration is carried out for three days. Obtained data in the form of corrosion rate, inhibitor efficiency, and inhibitor adsorption mechanism with a concentration from 0 ppm to 200 ppm using the method of weight loss. Steel corrosion potential, inhibitor efficiency, and equivalent electrical circuit models are obtained using the electrochemical method. In addition, Scanning Electron Microscope and Energy Dispersive X-ray Spectroscopy (SEM-EDX), and Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR) is used for samples characterization. In the immersion test, the corrosion rate decreased and the inhibitor efficiency increased with increasing inhibitor concentration. The smallest corrosion rate and the greatest inhibitor efficiency was obtained at a concentration of 200 ppm for ketoconazole and fluconazole, respectively 0.1302 mm/year and 0.1960 mm/year, and the inhibitor efficiency was 68.98% and 53.31%. While the inhibitor efficiency values obtained from EIS testing with a concentration of 200 ppm for ketoconazole and fluconazole were 59.35% and 53.39%, respectively. This proves that the number of organic elements, such as: O and N in the structure of chemical compounds plays an important role in improving the performance of adsorption. Both inhibitors are classified as mixed-type inhibitors by the inhibitor mechanism of physisorption and chemisorption. With the Rs-(CPEi/Ri)-(CPEp(Rp(CPEdl/Rct))) electric circuit model due to the use of inhibitors which show the formation of porous corrosion product passive layers and the formation of quasi-homogeneous adsorbed inhibitor layers.