Equivalence of hydrogen uptake in X70 pipeline steel via gaseous and electrochemical charging

This study examines hydrogen uptake in X70 pipeline steel using gaseous and electrochemical charging. Equivalent hydrogen fugacity was determined via electrochemical permeation in 0.1 M NaOH and validated by thermal desorption analysis. The results showed that equivalent hydrogen content can be achieved by both charging methods based on surface hydrogen activity, and the relationship obtained was observed to be material-specific. An overpotential of −0.7 V yielded a comparable hydrogen concentration to 10.34 MPa gaseous charging in the investigated X70 steel, offering a practical benchmark for similar pipeline steels. Also, the addition of recombination poison (As 2 O 3 ) enabled higher hydrogen fugacity and hydrogen uptake to be obtained at lower absolute overpotentials and charging current densities. • Equivalent hydrogen uptake in X70 steel was achieved using both gaseous and electrochemical charging. • Electrochemical hydrogen permeation reliably determined hydrogen fugacity with 0.1 M NaOH electrolyte. • Recombination poison addition enhanced hydrogen uptake at lower absolute overpotentials. • Hydrogen fugacity-overpotential relationships are material-specific and should be experimentally determined. • An overpotential of −0.7 V in 0.1 M NaOH yielded hydrogen content comparable to 10.34 MPa gaseous charging.