Study of the susceptibility of L485 pipeline steel to hydrogen embrittlement

Abstract

Energy transition, driven by the ambitious targets of the EU Green Deal to achieve carbon neutrality by 2050, emphasizes the urgency of addressing climate change. As part of this effort, through the European Hydrogen Backbone initiative, Europe aims to revolutionize its energy landscape. Central to this initiative is developing a hydrogen infrastructure, which will leverage existing and newly established pipeline systems. Notably, this effort involves repurposing a portion of the natural gas pipeline grid to facilitate hydrogen transportation, which is still under development. Most high-pressure gas and oil pipelines are, however, made of ferritic steels, which are known to be potentially degraded by the presence of atomic hydrogen [1], [2]. Replacing natural gas with hydrogen gas in the current pipeline grid, that operates at high pressures, might, therefore, accelerate the deterioration of mechanical properties [3]. It is crucial to also consider any structural variation in pipelines, including bends, cracks, or weld faults, as they can aggravate the interaction between hydrogen and materials. Besides, impressed current cathodic protection is frequently used to protect pipeline steels from corrosion. However, atomic hydrogen can as such also be induced in the material’s microstructure, equally resulting in a loss of structural mechanical integrity, especially when cathodic overprotection takes place [4]. Thus, during hydrogen transport, there are two potential hydrogen sources: the internal source, which refers to the hydrogen being transported and delivered, and the external source, due to cathodic (over-) protection. Both are expected to possibly contribute to the overall degradation of mechanical properties. Consequently, it is crucial to investigate these pipeline steels to comprehend the reasons behind their failure, also when in contact with hydrogen. In this context, fractography analysis is crucial for examining and characterizing fractured pipeline steel surfaces. This work aims to study fracture patterns, and characteristics of electrochemically hydrogen charged ex-situ quasi-static tensile tested L485 pipeline steel samples to understand the underlying causes and mechanisms of material failure due to hydrogen embrittlement. It is worth noting that this study focusses on hydrogen from an internal source.

Link to publication

Recommended citation: J. Jubica et al., "Study of the susceptibility of L485 pipeline steel to hydrogen embrittlement," in European PhD Hydrogen Conference 2024: book of abstracts, Ghent, Belgium, 2024.
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