Effect of Hydrodynamic Conditions, Temperature and Immersion Times on the Corrosion Inhibition Efficiency of API 5L X52 Steel in 1M HCl Containing 1H-1,2,4 or 1H-1,2,3-triazoles

From electrochemical means, the concentration effect of 1H-1,2,4 and 1H-1,2,3 triazoles on the corrosion behavior of API 5L X52 steel samples immersed in 1M HCl was evaluated. The results obtained through electrochemical impedance spectroscopy demonstrated that at stagnant and room temperature conditions, the IE increased with inhibitor concentration, although it reached an IE > 90 %, at 200 ppm, in both cases. It was found that for [1H-1,2,4-triazole] ppm, the IE value reached, ca. 85 %, at 40 rpm; however, it diminished then to ca. 65 % upon changing the working electrode rotation speed to 1000 rpm. A similar situation was observed for the 1H-1,2,3-triazole under static conditions, where a value of ca. 96 % was reached at 200 ppm, although it was also observed decreasing inhibition efficiency with increasing rotation speed. Furthermore, when the temperature of the corrosive media was increased , at static conditions and 100 ppm inhibitor, the IE values diminished to ca. 83.8 % for 1H-1,2,4-triazole and 77 % for 1H-1,2,3-triazole. For stagnant conditions, 100 ppm of either 1H-1,2,3-triazole or 1H-1,2,4-triazole at , an IE greater than 95 % was found even after 672 exposure hours to the corrosive media. The results showed that, in both cases, the triazoles inhibition mechanism involves blockage of the steel surface through a Langmuir-type physisorption process.