Investigating electrochemical charging conditions equivalent to hydrogen gas exposure of X65 pipeline steel

• Published in: Materials and corrosion 2024-03, Vol.75 (3), p.315-321
• Main Authors: Koren, Erik, Hagen, Catalina M. H., Wang, Dong, Lu, Xu, Johnsen, Roy
• Format: Article
• Language: English
• Subjects: Cathodic protection; electrochemical charging; Equivalence; equivalent fugacity; Gas permeation; Gas pressure; H2 gas charging; High strength low alloy steels; Hydrogen charging; hydrogen embrittlement; Hydrogen permeation; Hydrogen recombinations; Permeation; pipeline steel; Structural steels
• ISSN: 0947-5117; 1521-4176
• DOI: 10.1002/maco.202313931

In this study, we systematically investigate electrochemical hydrogen charging conditions equivalent to hydrogen gas pressures relevant for hydrogen transportation in X65 pipeline steel. By performing hydrogen gas permeation, a relationship for Sieverts' law was established, which was used in combination with electrochemical hydrogen permeation to determine the equivalent hydrogen pressure. The results revealed that cathodic protection simulated condition at –1050 mVAg/AgCl was equivalent to a hydrogen pressure of 12.3 bar. The addition of thiourea, a hydrogen recombination poison, and changing the applied potential in the cathodic direction increased the equivalent hydrogen pressure. In this way, an electrochemical charging condition equivalent to a potential hydrogen gas pressure for hydrogen transportation (200 bar) was determined. Relating gaseous and electrochemical hydrogen charging can ease the evaluation of repurposing pipelines for hydrogen gas transport. In this study, the equivalent hydrogen pressure was investigated using gaseous and electrochemical hydrogen permeation. The hydrogen recombination poison concentration and the applied potential are systematically changed to obtain the desired equivalent hydrogen pressure.