Hydrogen-related attack is a specific mechanism that can contribute to SCC (Stress Corrosion
Cracking), through its influence on internal stress and the microstructure due to atomic hydrogen
concentration diffused and accumulated during operation conditions due to the formation of atomic
hydrogen in presence and absence of polarization conditions (cathodic protection). In this work, an API
X-65 grade steel pipeline is exposed to NS4 synthetic groundwater solution in hydrogen permeation cell
type experiments in order to follow the hydrogen reaction in the cathodic compartment and to
characterize the total current between anodic and cathodic compartments and the parameters obtained
from polarization tests. A theoretical model based on adsorption coverage is used to characterize atomic
hydrogen that forms and diffuses within the steel, as a competition of the hydrogen and bicarbonate ions
for the available active sites at the interface.