Benchmark of J55 and X56 steels on cracking and corrosion effects under hydrogen salt cavern boundary conditions

Salt caverns have great potential to store relevant amounts of hydrogen as part of the energy transition. However, the durability and suitability of commonly used steels for piping in hydrogen salt caverns is still under research. In this work, aging effects focusing on corrosion and cracking patterns of casing steel API 5CT J55 and "H2ready" pipeline steel API 5L X56 were investigated with scanning electron microscopy and energy dispersive X-ray spectroscopy after accelerated stress tests with pressure/temperature cycling under hydrogen salt cavern -like conditions. Compared to dry conditions, significant more corrosion by presence of salt ions was detected. However, compared to X56, only for J55 an intensification of corrosion and cracking at the surface due to hydrogen atmosphere was revealed. Pronounced surface cracks were observed for J55 over the entire samples. Overall, the results strongly suggest that X56 is more resistant than J55 under the conditions of a hydrogen salt cavern.