Susceptibility of carbon pipeline steels operated in natural gas distribution network to hydrogen-induced cracking
H. М. Nykyforchyn, Leonid Unigovskyi, Olha Zvirko, Myroslava Hredil, H. V. Krechkovska, О. Z. Student, Oleksandr Tsyrulnyk
Abstract
The existing network of both transit and distribution gas pipelines has recently been proposed to be used for the transportation of hydrogen as an energy fuel in the multifaceted structure of the development of renewable energy sources. From this point of view, the paper considers the sensitivity of a long-term operated steel of distribution gas pipeline to hydrogen assisted cracking as a result of preliminary electrolytic hydrogenation of flat tensile specimens, followed by determination of strength and plasticity characteristics. The research methodology has two features: (i) the specimens are cut out from the pipe in the transverse direction to the pipe axis; in this case the fracture plane is parallel to the rolling direction of metal sheet from which the pipes were made; (ii) specimen thickness is 1.2 mm maximally providing through hydrogenation. The study additionally includes determination of hydrogen concentration in the steel, and fractographic analysis. It is shown that the low-carbon steel of the 52-year-old gas pipeline with high residual hydrogen content especially sensitive to hydrogen assisted cracking, indicated by signs of low-energy fracture at the micro scale.