Qualification of elastomer materials for CO₂ pipeline systems

Carbon Capture, Utilisation and Storage is essential to reduce anthropogenic greenhouse gas emissions and limit the average global temperature rise below the 2°C target. In order to promote safe operations throughout the chain, considerations on the performance of transportation and conditioning materials, including propensity for elastomers degradation are some key engineering challenges to be considered for CO2 transportation systems. Therefore, this work presents a characterisation methodology and findings on the performance of several elastomer materials undergoing prolonged (up to 400 h) exposure to supercritical CO2 under pipeline conditions (95 bar and 40^oC). The work considered the presence of saturated H2O in the stream as well as the addition of H2S or SO2 as contaminants (500 ppm). Findings show that Neoprene, Ethylene Propylene and Buna N seals have a propensity to lose mass after the exposure, potentially due to degradation of plasticisers contained in their matrix. PTFE-coated samples of such materials moreover exhibited significantly higher mass loss, suggesting degradation of the coating in this environment. Conversely, Viton showed a modest increase of mass after the test, potentially representative of a high-degree of interaction between the material and the fluid. Viton moreover demonstrated to be a potentially unsuitable material choice due to its propensity for rapid gas decompression damage, manifested in extensive presence of cracks on the cross-section surface.