Construction of a damage model for rapid depressurization of O-ring seals in high-pressure CO₂ long-distance transmission pipelines

Objective Against the backdrop of global climate change driving the "dual carbon" goals to the forefront of strategic focus, Carbon Capture, Utilization and Storage (CCUS) technology plays a pivotal role in addressing climate change. As the core infrastructure for large-scale CO₂ transportation in CCUS systems, the reliability of long-distance pipeline sealing systems directly impacts the safety and efficiency of the technical process. Although existing research has made progress in understanding the damage mechanisms of rubber O-rings under high-pressure CO₂ environments, the coupling mechanism between gas diffusion and rubber deformation during rapid decompression remains insufficiently studied. Methods To address this issue, a multiphysics coupling model considering CO₂ dissolution and permeation, rubber nonlinear deformation, and material damage evolution is established based on Fick's diffusion law, Mooney-Rivlin hyperelastic constitutive model, and maximum principal strain damage criterion. The model is solved parametrically using the finite element method, systematically investigating the performance response of four typical sealing materials—HNBR, NBR, EPDM, and NR—under rapid decompression. The study focuses on analyzing the effects of compression ratio, pressure level, decompression speed, and cavity size. Results The research findings indicate that under 4MPa external pressure, HNBR demonstrates optimal resistance to rapid decompression, with a maximum logarithmic strain of only 0.17. In contrast, EPDM exhibits a peak strain of 1.42, exceeding its fracture elongation and resulting in rupture. The materials' resistance to rapid decompression damage follows the order: HNBR>NR>NBR>EPDM. The strain response of HNBR to compression ratio differs from other materials due to the unique pressure difference characteristics in its decompression phase and its inherent material properties. For NBR, EPDM, and NR, moderate increases in compression ratio can reduce strain during rapid decompression. Additionally, increasing cavity diameter, accelerating decompression speed, and rising external pressure all lead to increased strain in the O-ring's internal cavity. Conclusion The numerical model developed in this study can accurately predict the damage behavior of O-rings during rapid decompression in high-pressure CO₂ environments, providing reliable theoretical support for material selection, structural parameter design, and operation maintenance strategy formulation of pipeline sealing systems. This research contributes to enhancing the safety and operational efficiency of CCUS technology, thereby advancing the realization of the "dual carbon" strategic goals.