ABSTRACT

As part of the Horizon 2020 project HyStories, the possibility of hydrogen storage in old, depleted gas reservoirs and natural gas storage facilities is being investigated throughout Europe. Within the scope of this project, the work package "materials and corrosion" has the objective of testing the applicability of selected pipe materials with respect to hydrogen embrittlement. For this purpose, a welded carbon steel grade J55 with a ferritic-pearlitic microstructure was investigated by using high pressure high temperature autoclave tests, permeation tests and analysis of uptaken hydrogen. For the autoclave tests, tensile samples have been examined that were loaded by a spring at 90% of yield strength, and samples were also examined to determine the hydrogen uptake. After completion of the tests, the hydrogen uptake was analyzed by thermal desorption spectroscopy. Four main gas compositions were used for the autoclave tests: 120 bar H2, 120 bar H2 + 15 bar CO2, 120 bar H2 + 1 bar H2S, and 120 bar H2 + 15 bar CO2 + 1 bar H2S whereby the tests were carried out with and without the addition of electrolytes with a concentration of 1 and 200 g/l sodium chloride. Moreover, the experiments were conducted at room temperature and 120°C. Test duration was 720 hours. Prior to autoclave testing effective diffusion coefficient was determined to characterize diffusion behavior of hydrogen through the weld material. Results show a low hydrogen uptake even at most severe conditions. Additionally no specimens failed during autoclave constant load testing. Welded J55 is recommended as a suitable tube material for subsurface hydrogen storage.

Statement of Impact

- J55 can be used for underground hydrogen storage.

- Welds also show no embrittlement.

- Welded J55 can be used up to 120 bar H2 + 1 bar H2S + artificial brine.

INTRODUCTION

Corrosive environmental media may lead to a significant degradation of the mechanical properties of the materials. Individual experimental investigation and analysis concepts are available at the Institute of General and Analytical Chemistry for the evaluation of different materials under pressurized hydrogen. Hydrogen technologies will enable decarbonization. Research in this area will also play an essential role in energy storage. For this reason, it is important to advance research in this area, to work against hydrogen embrittlement (HE). The largest susceptibility to HE of steels is at room temperature, but hydrogen absorption from the gas phase increases strongly at higher temperatures [1]. In the literature, increased hydrogen absorption due to the presence of an electrolyte is also described. The hydrogen partial pressure, the pH value of the electrolyte and the presence of recombination inhibitors are mentioned as further influencing factors [2].

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