Electrochemical evaluation of the corrosion behaviour of API-X100 pipeline steel in aerated bicarbonate solutions

This work is devoted to evaluating electrochemical corrosion aspects of API-X100 in bicarbonate solutions. They were prepared to be aerated; chloride free and 3 wt.% chloride containing solutions of 0.1, 0.5, and 0.8 M bicarbonate at 20, 40, and 60 °C. Open circuit potentials, polarization potentiodynamics, and impedance spectroscopy were utilized. The behaviour exhibited a cathodic dependence on bicarbonate and temperature where the corrosion rates consequently increased. Chloride prevented stable passivation and increased the anodic sensitivity. EIS and polarization results were in agreement and impedance in the presence of chloride was temperature dependent.

► Cathodic influence of bicarbonate and temperature on OCP.
► Kinetic characteristics are discussed from potentiodynamic polarization tests.
► Equivalent circuits are proposed from EIS data.