Ultimate purpose of the fracture management and control for ship structure design are “to achieve zero serious accident”, that is, “to avoid ship sinking”. Especially, for the structure design of large ships, how the crack arrest structure (crack arrestor) is applied to is most important. By the way, the ship capacity as in container ship is growing year and year, and in the recent decade ultra-large container ships of 20,000 TEU class have been developed and built. Therefore, the crack arrestor becomes important more and more.
In this study, based on the past serious accidents of the hull structure for up to newly developed very large container ship from general cargo ship in World War II, we considered and discussed the required brittle crack arrest toughness of structural steel plates for the hull structure design of these ships.
Finally, we discussed the required brittle crack arrest toughness value Kca for the very thick welded steel plates for 20,000 TEU class container ships are being built recently.

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When setting the allowable stress value of various strengths in codes and standards, it may be determined based on the sample data obtained in the strength experiment. In this case, it is necessary to determine the allowable stress probabilistically in consideration of the sample size so as to satisfy the target reliability and confidence level. In recent years, there is an increasing need to determine the allowable stress probabilistically. Therefore, in this article, the probabilistic determination method of allowable stress is summarized. Some examples for calculation will be given. Finally, the treatment of allowable stress on codes and standards are also shown.

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Hydrogen energy is a candidate of the promising solutions for the global environmental issues. Hydrogen production, transportation and storage are key technologies to establish hydrogen supply chain system. Liquid hydrogen would be the most effectual measure for transporting and storing hydrogen. Large scale storage tank will be required for storage of liquid hydrogen from abroad. However, there is no experience to build this kind of storage tank in the world and some difficult issues are existing for construction.
This paper describes the two measure issues for construction one is a safety for materials and the other is a thermal insulating property, and action assignment to address these issues.

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The author has reported incidents of storage facilities for energy products at the EST-1 Committee of High Pressure Institute of Japan. The information was obtained from the internet when the incidents occurred. In this paper, 42 incidents of storage facilities for energy products which occurred overseas in the first half of 2021 are reported.

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