The effect of H2S concentration on the corrosion behavior of API 5L X-70 steel

This work presents electrochemical data measured during the corrosion of API 5L X-70 pipeline steel immersed in aqueous environments containing dissolved H₂S. Three different electrolyte were used: a 3 wt% NaCl solution containing 100, 650 and 2,550 ppm of H₂S respectively. The corrosion of steel is described by means of electrochemical impedance spectroscopy. The electrochemical data obtained from the steel monitoring are presented in terms of Nyquist plots. The influence of the total H₂S concentration as well as the effect of temperature on the corrosion of API 5L X-70 steel were also studied. In the presence of H₂S the R_ct values decrease as the H₂S concentration increases.