Submitted by mvoppen on Thu, 07/08/2021 - 14:29

The transition of existing natural gas grid infrastructures towards the transport and storage of hydrogen gas plays a prominent role in the decarbonization of the energy landscape and therefore nicely fits within the European Green Deal. This transition requires prior confirmation of the fitness-for-service of the existing gas grid for gaseous hydrogen transport. Hydrogen absorption into high-strength low alloy pipeline steel pipes and welds potentially gives rise to material degradation, which may be reflected in accelerated fatigue crack growth, embrittlement and/or ductility loss. Depending on the extent of hydrogen assisted degradation, welds containing flaws that were historically qualified as acceptable for natural gas transport may potentially require renewed special attention. Moreover, cathodic (over)protection which protects the infrastructure against corrosion generates additional hydrogen from an electrochemical source, which may intensify the material degradation from gaseous hydrogen.

The effects of hydrogen on pipeline steels and welds are still under debate. There is a lack in fundamental understanding of both the material (microstructural) properties contributing to degradation sensitivity, and experimental and numerical techniques to model the process of material degradation. Moreover, a possible strategy requiring further attention is to limit the uptake of gaseous hydrogen by the pipeline material by the addition of small amounts inhibitors to the gas (mixture). The extent to which this may serve the integrity of the pipeline is to be investigated.

Within the abovementioned research context, two PhD researchers will be working on a full time basis (project duration: four years): one having a materials engineering background (focus of this vacancy), and one having a mechanical engineering background. There will a strong collaboration between both researchers in terms of material and mechanical characterisation, and sharing of information will be required in both directions. Moreover, the work will be embedded in research groups where other researchers are working on related topics.

This vacancy aims to select the PhD researcher having a materials engineering background (a separate vacancy has been published for the other PhD researcher). This researcher will experimentally focus on the role of potential addition of inhibitors to gaseous hydrogen in the hydrogen/material interaction and the resulting hydrogen uptake by pipeline steels. Moreover, the potential effect on hydrogen induced cracking generated by cathodic (over)protection in combination with gaseous hydrogen uptake will be incorporated as well. (S)he will also be heavily involved in experimental material characterisation in terms of microstructural and micromechanical properties in absence and presence of hydrogen, and linking these with macromechanical properties. A major goal is to understand the interaction on microstructural level between the investigated material and hydrogen. Both bulk and surface evaluation will be relevant to develop methodologies to screen the hydrogen susceptibility of pipeline steels in the abovementioned circumstances.

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