Crack Behavior and Safety of Hydrogen Pressure Vessels under Changing Pressure Conditions

In this study, the fatigue lives of a 300-L high-pressure vessel and 1000-L medium-pressure vessel were determined using ANSYS. The maximum operating pressures were set at 83 and 50 MPa using SA-372 Grade J/Class 70 material. Considering the axisymmetric shape of the pressure vessels, crack shapes were established according to ASME Band PV code standards to evaluate the impact of internal cracks. The analysis results showed that the fatigue life of cracks oriented along the length was significantly shorter than that of circumferential cracks. A trend was observed in which the fatigue life increased as the crack depth decreased, and the fatigue life increased proportionally with the pressure differential. These findings provide crucial information for assessing the safety of pressure vessels and clearly demonstrate the effects of the crack size and operating pressure range on the fatigue life. The results of this study can serve as a foundationfor enhancing the safety of pressure vessels.