Development of a damage model for rapid decompression of O-ring seals in high-pressure and long-distance CO₂ pipelines

Objective Long-distance pipelines are essential for large-scale CO₂ transportation within the Carbon Capture, Utilization, and Storage (CCUS) system, where the reliability of sealing systems directly influences safety and efficiency. While research has advanced the understanding of the damage mechanisms affecting rubber O-rings in high-pressure CO₂ environments, the coupling mechanism between gas diffusion and rubber deformation during rapid decompression remains underexplored.

Methods In response to this issue, a multi-physics coupling model was developed, incorporating CO₂ dissolution and permeation, nonlinear rubber deformation, and material damage evolution. This model is based on Fick’s law of diffusion, the Mooney-Rivlin hyperelastic constitutive model, and the maximum principal strain damage criterion. Utilizing the finite element method, a parametric solution was obtained to systematically investigate the performance response under rapid decompression of four typical sealing materials: Hydrogenated Nitrile Butadiene Rubber (HNBR), Nitrile Butadiene Rubber (NBR), Ethylene Propylene Diene Monomer (EPDM), and Natural Rubber (NR). The study focuses on analyzing the effects of factors such as the cavity size, compression ratio, pressure level, and decompression rate.

Results The four materials’ resistance to damage during rapid decompression in order from high to low is HNBR, NR, NBR and EPDM. Under an external pressure of 4 MPa, HNBR demonstrated the best resistance to rapid decompression, exhibiting a maximum logarithmic strain of only 0.17, while EPDM’s peak strain reached 1.42, surpassing its elongation at break and resulting in rupture. The influence of compression ratio on the strain of HNBR differed from that of other materials due to the unique pressure difference characteristics of the cavity during decompression and HNBR’s material properties. In contrast, NBR, EPDM, and NR exhibited reduced strain during rapid decompression with a moderate increase in compression ratio. Furthermore, an increase in cavity diameter, higher external pressure, and a faster decompression rate would result in increased strain within the cavity of the O-ring.

Conclusion The developed numerical model accurately predicts 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 the formulation of operational and maintenance strategies for pipeline sealing systems, thus facilitating the achievement of the “dual carbon” strategic goals.