Hydrogen permeation in pipeline steels

E. Fallahmohammadi, F. Bolzoni, G. Fumagalli, G. Re, L. Lazzari
politecnico di milano, IT

Keywords: hydrogen permeation in steel, trapping, hydrogen diffusion, H2S

Summary:

In a previous phase of this research, two sour service pipeline steels, a carbon steel API 5L X65 and a low alloy one ASTM A182 F22, showed a remarkable reduction of the fracture toughness after electrochemical charging with hydrogen. Diffusion and trapping mechanisms of hydrogen are studied in this paper in order to better understand the charging phenomenon and the hydrogen distribution in steel pipeline material. Hydrogen permeation was studied by means of the electrochemical method developed by Devanathan and Stachurski. The effects of some metallurgical features such as microstructure and inclusions have been evaluated studying hydrogen diffusion on the same materials in fully quenched conditions and on X52 steel not specifically produced for sour service.