Corrosion Behaviors of X65 Pipeline Steel After Hydrogen Charging in Soil Solutions

In view of the complexity in soil environment caused by long distance transportation of oil and gas pipelines,corrosion problem from hydrogen has received increasing attention.The corrosion behaviors of X65 pipeline steel after electrochemical hydrogen charging with different times in four simulated soil solutions(in Geermu,Dagang,Daqing,and Lasa) were investigated using the polarization test and electrochemical impedance spectroscopy(EIS) measurement.Resultsshow that the open circuit potential(OCP) of X65 decreases with prolonging charging time in a type of solution.The polarization curves in the four solutions show that X65 with different charging times presents similar electrochemical behavior,which is active in both the anode and the cathode.The smaller the corrosion current density is,the slower corrosion rate is.EIS spectra indicates that the ranking of charge transfer resistance from the biggest is Geermu,Dagang,Daqing and Lasa.It is consistent with the analysis results of polarization curves.