In this period of transition, attention to the environment and clean sources of energy are topics that are acquiring increasing interest.
With particular reference to the energy industry, hydrogen is becoming the ideal candidate for the replacement of fossil fuels. The distribution of hydrogen is forced to be conducted through the usage of the existing net of pipelines; therefore, using pipes fabricated in different periods (from 1970 up to present). This means, the prediction of the behavior of the pipeline steel under H2 charging (gaseous or cathodic) is not easy and requires a big specific effort to be performed.
Therefore, in this work a vintage API 5L grade X52 pipe fabricated in 1970 was characterized both under cathodic and gaseous hydrogen environment; a comparison between mechanical tests with in situ H2 charging was compared with results obtained from KIH test in gaseous hydrogen at 80 bar and a complete picture of the behavior of the material was obtained. Furthermore, the results obtained from slow strain rate tests on notched specimens up to 1500 bar are presented and discussed.
In the world of today hydrogen finds a relevant role as main candidate for the energy transition; therefore, the hydrogen embrittlement needs to be deeply studied to better assess the behaviour of new and vintage materials thus allow the transport and distribution of such gas in the countries. [1][2]. Indeed, the current gas pipelines are composed by steels (mainly grades X65 and X52) fabricated in a wide range of time: from 70s up to 2023 [3]. Furthermore, such pipes are joined through welds, (millions of welds just in Italy) and therefore, a specific attention have to be considered because of the heat affected zones and the residual stresses typically related with welding.
Therefore, the understanding of the behaviour of inaccessible materials and welds becomes necessary to perform an accurate assessment of the suitability of the pipeline to hydrogen service.
