Pipeline durability and integrity issues at hydrogen transport via natural gas distribution network

Abstract

Hydrogen will play a significant role in a decarbonised energy system in the coming decades. Extensive infrastructure exists for distribution of natural gas and it is an obvious step to assess it to be used for supply hydrogen or mixtures with natural gas. The durability and integrity issues in existing natural gas distribution steel pipelines associated with hydrogen embrittlement of steel at transporting hydrogen or mixtures natural gas with hydrogen are considered. Two mechanisms of steel hydrogenation from pipe internal surface are taken into account, namely, as a result of electrochemical corrosion due to presence of moisture in transported gas, and molecular hydrogen dissociation. Dissipated microdamaging in the bulk of the pipe wall is distinguished as the main factor of manifestation of hydrogen embrittlement of steel and its durability loss, increasing a risk of structural integrity violation. A sensitivity of some physico-mechanical properties of pipeline steels to hydrogen degradation is analysed. Some technological solutions are considered which should accompany experimental research on the assessment of the pipe serviceability at supply hydrogen or mixtures natural gas with hydrogen, including long-term exposing of pre-loaded specimens in hydrogen or hydrogen-natural gas mixture.