Numerical simulation of ductile crack propagation velocity in CO₂ pipeline

<b>[Objective]</b> Carbon Capture, Utilization, and Storage(CCUS) technology is recognized as a crucial technology for strategically reducing CO₂ emissions. Supercritical CO₂ pipeline transmission represents the most cost-effective method to connect carbon capture with carbon storage. Due to the decompression wave characteristics of supercritical CO₂ and the Joule-Thomson effect of CO₂, CO₂ pipelines are susceptible to long-distance crack propagation following fractures, posing a threat to the safety of pipeline operation. <b>[Methods]</b> Instrumented impact experiments were conducted, using transverse specimens from the base metal of L360M pipes, to investigate the crack propagation mechanism of supercritical CO₂ pipelines. Following that, a numerical simulation model was established and the Cohesive Zone Model(CZM) was utilized to describe material damage. By comparing curves from the experiments and simulations, parameters were calibrated for the CZM, leading to the development of a finite element model for crack propagation in supercritical CO₂ pipelines. Simulations were performed after inputting the calibrated CZM parameters into the finite element model, to explore the effects of internal pressure, wall thickness, and pipe diameter on the crack propagation velocity. <b>[Results]</b> The CZM effectively simulated the dynamic progression of crack propagation, and the simulation results exhibited an overall trend consistent with the experimental results. The CZM parameters calibrated and verified through comparison with experimental results proved effective in numerically simulating crack propagation within the pipeline model. In supercritical CO₂pipelines, the crack propagation velocity increased with higher internal pressure, larger pipe diameter, and lower wall thickness.<b>[Conclusion]</b> Crack arrest pressures corresponding to different pipe diameters and wall thicknesses and the minimum wall thickness suitable for a pipe diameter of 323 mm were identified for supercritical CO₂ pipelines through calculations based on the above results.The research outcomes lay a theoretical groundwork for understanding crack arrest in supercritical CO₂ pipelines and offer practical engineering applications with a useful reference point.