Closed-loop test chain for investigation of hydrogen uptake from high-pressure environments: (a) charging of idealized model sample, (b) measurement by carrier gas hot extraction in Department 9, (c) simulation of hydrogen pipeline and extrapolation of service behavior
Source: BAM
Green hydrogen the energy carrier in future. Hydrogen has low volumetric energy density (12.7 MJ/m³), especially compared to methane (40 MJ/m³), as the main constituent of natural gas. In order to distribute large volumes of hydrogen, compression or liquification of the gas is required. Hydrogen partial pressures up to 200 bar are common in industry (e.g., for gas bottles), while pressures up to 1,000 bar will be considered in future (e.g., for compressed hydrogen tube trailers or gas stations). One of the challenges for using gaseous hydrogen is establishing reliable and safe structures including pipelines and pressure vessels for transmission and storage. Typically applied metals are exposed to high pressure hydrogen gas may undergo detrimental failure by embrittlement. Understanding the mechanisms and driving forces of hydrogen absorption on the surface of metals is crucial for avoiding hydrogen embrittlement.
In this study, the effect of stress-enhanced gaseous hydrogen uptake in bulk metals is investigated in detail. For that purpose, a generalized form of Sievert's law is derived from thermodynamic potentials considering the effect of microstructural trapping sites and multiaxial stresses. This new equation is parametrized and verified using experimental data for structural steels, which were charged under gaseous hydrogen atmosphere at varying pressures up to 1,000 bar. The role of microstructural trapping sites on the parameter identification is critically discussed. As final outcome, a parametrized equation was established to calculate the stress-enhanced hydrogen solubility of idealized geometries that demonstrate two practical application cases in terms of a thin-walled pipelines and a thick-walled pressure vessel during service. The results show that the measured and calculated hydrogen concentrations in pipes and pressure vessels up to 0.3 weight-ppm at 200 bar and 0.6 weight-ppm at 1,000 bar are not negligible and need careful examination and consideration for the assessment of hydrogen embrittlement susceptibility. The study is a part of the ongoing hydrogen collaboration between BAM and Technical University of Graz, Austria.
Enhanced gaseous hydrogen solubility in ferritic and martensitic steels at low temperatures
A Drexler, Florian Konert, Oded Sobol, Michael Rhode, J Domitner, C Sommitsch, Thomas Boellinghaus
published in The International Journal of Hydrogen Energy, Volume 47, Issue 93 Pages 39639 - 39653
BAM Component Safety und Testing Devices and Equipment