EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

The power-to-gas technology, which uses excess electricity from regenerative sources for generating hydrogen gas by means of electrolysis, represents a promising future concept for energy storage. Hydrogen gas would open up the possibility for storing large amounts of energy for long periods of time, and the already existing infrastructure of natural gas grids could be used for transporting hydrogen gas. Pipeline materials which have been used for natural gas grids range from low-strength steels (LSS) to high-strength steels (HSS). While LSS pipes were predominant in the past, HSS pipes with comparatively thin walls are favored nowadays. However, the greater sensitivity of HSS to hydrogen embrittlement may cause problems and requires evaluation before feeding hydrogen into existing gas grids. Therefore, the present work evaluates the resistance of two different pipeline steels against hydrogen embrittlement by means of slow strain rate testing (SSRT) of electrochemically charged samples. Electrolyte type, current density and charging duration were adjusted to ensure that the hydrogen contents of the samples exceed the expected uptake of gaseous hydrogen in future hydrogen gas pipelines. Both notched and unnotched flat samples were machined from pipes of carbon steels API 5L Grade A and L 485 MB, respectively. Moreover, flat samples with notches located directly at the weld seam were machined from welded pipes. The result obtained in this work is the evaluation of the hydrogen embrittlement susceptibility of the tested pipeline materials.