Hydrogen energy systems have attracted interest in the search for solutions to global energy challenges. One of the technical problems of the rubber O-rings used in high-pressure hydrogen devices is the occurrence of internal fractures known as blisters, which are caused by gas decompression. Our studies revealed that the fracture of the rubber deteriorated sealing property and durability of the O-ring after several pressure cycles. However, the O-rings used in the 70-MPa-class hydrogen vessels of Fuel Cell Vehicles are generally required to withstand 5,500 pressure cycles.

This paper entitled technical issues of rubber materials for high-pressure hydrogen seals reports a fracture behavior and a state change of rubber O-ring. We evaluated the sealing property and durability of rubber O-ring under realistic pressure cycle conditions. Long-term sealing durability tests were successfully performed using 5,500 pressure cycles without fatal leakage, fracture, or change in the elastic modulus. These results indicate that silicone rubber O-ring has good low-temperature seal and long-term durability. The development of the seal technology which this paper reported and accumulation of the knowledge such as the fracture mode become more and more important in future.