Fitness-for-Service Assessment of Hoop-Wrapped Vessel with Metal Liner in High-Pressure Hydrogen Environment

Hoop-wrapped vessels with metal liners (Type II vessels) are susceptible to the risks of brittle fracture and fatigue failure in high-pressure hydrogen environments. However, there is limited research concerning fitness-for-service (FFS) assessments of Type II vessels. An FFS assessment was conducted on a specific Type II vessel designed for high-pressure hydrogen storage. The mechanical properties of the liner material 4130X were obtained through in situ mechanical testing in a hydrogen environment. Based on the measured data, the stress distribution within the Type II vessel under different working conditions was determined using a finite element analysis by ANSYS Workbench 2019 R2 software. A leak-before-burst (LBB) analysis and a brittle fracture assessment of the Type II vessel were performed using the failure assessment diagram (FAD) methodology. The results indicate that the measured fracture toughness of 4130X under high-pressure hydrogen is 46 MPa·m0.5, which is significantly lower than the 178 MPa·m0.5 required for LBB failure for the studied vessel. However, the vessel remains in a safe state when the crack depth is under 3.03 mm. Furthermore, the remaining fatigue life of a Type II vessel containing a crack was calculated. The relationship between the non-destructive testing (NDT) capability requirement and the inspection interval for this type of vessel was explored, providing references for establishing inspection schedules for Type II vessels.