Experimental comparison of gaseous and electrochemical hydrogen charging in X65 pipeline steel using the permeation technique

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

“…The calculated S is 0.0095 wppm bar –1/2 , which is slightly lower than determined in a previous study for a hot rolled and welded X65 pipeline steel. [ 16 ] S is almost three times less than reported for a 3.5 NiCrMoV martensitic steel, [ 18 ] however, it is two to three times higher than for a martensitic advanced high strength‐steel [ 17 ] and a dual phase steel. [ 19 ] It is emphasized that the surface condition during gas permeation differs significantly from the inside of a pipeline in operation, for example, presence of an oxide layer.…”

“…[ 32 ] A detailed description of the gas permeation set‐up and electrochemical permeation set‐up was described in a previous paper. [ 16 ] In the detection chamber, for both gas and electrochemical permeation, a 0.1 M NaOH solution (pH = 12.6) and an applied potential of +315 mV SCE was used to ensure hydrogen oxidation. For gaseous hydrogen charging, the applied hydrogen gas pressures were 10, 50, and 100 bar.…”

“…$${f}_{{{\rm{H}}}_{2}}$$ is related to the hydrogen pressure, $${p}_{{{\rm{H}}}_{2}}$$, through the Abel–Noble equation of state, Equation (), where b denotes a constant (1.584 × 10 −5 m 3 mol −1 ), T denotes the temperature in K, and R denotes the gas constant (8.314 J K −1 mol −1 ). [ 37 ] The method to determine the equivalent hydrogen fugacity, $${f}_{{{\rm{H}}}_{2}}^{\text{eq}}$$, is described in detail in a previous paper [ 16 ] and is based on work reported by Atrens and colleagues. [ 14,15,17 ] It is considered that charging conditions that produce the same C 0R in a steel are equivalent.…”

“…Pd facilitates hydrogen oxidation on the detection side, [31] while on the charging side, Pd is applied to overcome the surface impedance which can be caused by an oxide layer during gaseous hydrogen charging. [3,13,16]…”

“…[2,12] Relating electrochemical and gaseous charging, would enhance the comparability of HE investigations performed under different charging conditions. The equivalence between electrochemical and gaseous charging has previously been investigated by hydrogen permeation, [13][14][15][16] thermal desorption analysis, [17][18][19] and by measuring the hydrogen pressure developed in a hollow sensor during charging. [20] While these studies investigated the pressure equivalency from common electrochemical charging conditions, a systematic approach to determine electrochemical charging conditions equivalent to pressures relevant for hydrogen gas transportation is lacking.…”