The effect of SSRT (slow strain rate testing) in the presence of hydrogen (in-situ SSRT test) was investigated for CrMo and CrMoV steels and compared with that of hydrogen addition after pre-straining (pre-SSRT test). The amount of hydrogen trapped by dislocations (A1 hydrogen content) has a same linear relationship with the amount of strain as in the pre-SSRT test. The A1 hydrogen content is proportional to the amount of hydrogen trapped by cementite (A0), grain boundary (A2), and two types of vanadium carbides (V1 and V2). The proportionality coefficients are the same as in the pre-SSRT test. However, the ratio of A2 to A1 is virtually large in the in-situ SSRT test. The amount of hydrogen trapped in vacancies (B), vacancy clusters (C) or microvoids (D) is the same as in the pre-SSRT test when plastic strain at fracture is used. For high-strength materials sensitive to hydrogen content, owing to the increased amount of A2 hydrogen though in-situ SSRT, brittle IG fracture occurs at stresses near the yield point. If the material is low in strength and insensitive to IG fracture due to hydrogen, work hardening proceeds beyond yield point and the dislocation density increases. This results in the formation of B, C, and D sites, and ductile fracture at decreasing load.

View full abstract

Ammonia is gaining significant attention as a key component in the push towards carbon neutrality due to its dual role as a carbon-free fuel and a hydrogen carrier. Its ability to burn without emitting carbon dioxide makes it an attractive option for reducing greenhouse gas emissions. As global demand for ammonia is expected to rise, efforts to develop large-scale storage tanks for ammonia are underway to meet this anticipated need. In light of the growing interest and potential risks associated with large ammonia storage tanks, it is crucial to examine past incidents to inform risk assessment and improve safety measures. Since 2011, the EST-1 Committee of the High Pressure Institute of Japan has been collecting data on incidents at storage facilities for various energy products. To date, approximately 3,800 incidents have been reported, with 60 specifically related to ammonia storage tanks. In this paper, these incidents have been analyzed and summarized to serve as a reference for evaluating the risks associated with large ammonia storage tanks.

View full abstract