Investigation of effectiveness of toroidal ring crack arrestors for running ductile fracture control in CO2 pipelines using fluid-structure interaction analyses

The increasing demand for carbon capture, utilization, and storage to mitigate greenhouse gas emissions has led to greater interest in the safe transportation of carbon dioxide (CO₂) through pipelines. CO₂ is preferably transported in its dense or supercritical phase; however, pipelines operating in these conditions are particularly susceptible to running ductile fracture (RDF). This study aims to assess the effectiveness of toroidal ring crack arrestors for preventing RDF in dense-phase and supercritical CO₂ pipelines by carrying out three-dimensional the fluid–structure interaction analyses to simulate the RDF process. The coupled Eulerian-Lagrangian approach is employed to capture the interaction between crack propagation and CO₂ decompression that is assumed to be isentropic and in homogenous equilibrium conditions. The effects of the temperature drop resulting from the decompression on the fracture toughness of the pipe steel are ignored. Parametric analyses are performed on a hypothetical CO₂ pipeline with representative pipe attributes and operating conditions. To focus on the effects of geometric parameters for the toroidal ring on the crack arrest effectiveness, the rings are modelled as rigid bodies as a reasonable first approximation. The analysis results provide insights into how key design parameters such as the ring spacing and radial clearance influence the effectiveness of toroidal ring arrestors and guidance on optimizing the design of toroidal ring arrestors. This study demonstrates the feasibility and advantages of using advanced fluid–structure interaction model to evaluate and enhance the structural integrity of CO₂ pipelines.