Permeability, solubility and diffusivity of hydrogen isotopes in stainless steels at high gas pressures

In this report, we provide a framework for describing the permeability, solubility and diffusivity of hydrogen and its isotopes in austenitic stainless steels at temperatures and high gas pressures of engineering interest for hydrogen storage and distribution infrastructure. We demonstrate the importance of using the real gas behavior for modeling permeation and dissolution of hydrogen under these conditions. A simple one-parameter equation of state (the Abel–Noble equation of state) is shown to capture the real gas behavior of hydrogen and its isotopes for pressures less than 200 MPa and temperatures between 223 and 423 K. We use the literature on hydrogen transport in austenitic stainless steels to provide general guidance on and clarification of test procedures, and to provide recommendations for appropriate permeability, diffusivity and solubility relationships for austenitic stainless steels. Hydrogen precharging and concentration measurements for a variety of austenitic stainless steels are described and used to generate more accurate solubility and diffusivity relationships.