Synergistic effect of O2-Cl− on localized corrosion failure of L245N pipeline in CO2-O2-Cl− environment

To enhance the understanding of the corrosion mechanism on rapid perforation failure, the corrosion behavior of L245N with the synergistic effect of O2-Cl− and different Cl− contents in CO2-O2-Cl− environment were studied by weight-loss test and characterization analysis. It showed that the O2 was the dominant factor inducing localized corrosion and the synergistic effect of O2-Cl− in CO2-O2-Cl− environment mainly accounted for the growth of the corrosion, because porous Fe oxides generated by O2 promoted the mass transfer and catalysis of Cl− and Cl− in turn promoted the expansion of localized corrosion pits. The increase of the Cl− under low content enhanced the synergistic effect with O2, while high content of Cl− (3000–5000 mg/L) could reduce the solubility of CO2/O2 and replace the adsorption of corrosive medium and ions on the substrate surface, inhibiting the cathodic process of corrosion reaction.