Engineering C^*-integral and COD estimates for nonidealized circumferential through-wall cracked pipes at elevated temperature

In this study, creep fracture mechanics parameters, C^*-integral and crack opening displacement (COD) rate, are estimated for a nonidealized circumferential through-wall crack (TWC) in pipes. The GE/EPRI and enhanced reference stress (ERS) methods are employed. As for creep condition, the Norton and RCC-MRx creep models are considered for secondary and primary-secondary creep strain, respectively. The bending moment, axial tension, and internal pressure are applied to a pipe with a nonidealized circumferential TWC, as individual loads. Three-dimensional elastic-creep finite element (FE) analyses are performed, and the predictions from the GE/EPRI and ERS methods are compared with FE results. For the Norton creep model, both methods show good agreement with the FE results. For the RCC-MRx creep model, only the ERS method can be used, and it provides accurate predictions comparing with FE results. Based on the comparison results, the use of the present engineering C^*-integral and COD estimation methods for nonidealized circumferential TWC is validated.