Internal Integrity Risks in Dense CO2 Pipelines: Bridging Testing and Engineering

Abstract Current Carbon Capture, Utilisation and Storage (CCUS) projects aim at transporting CO2 streams directly generated from industrial processes and holding a wider spectrum of contaminants e.g. sulphur/nitrogen oxides. The challenge of impurities in relation to defining safe CO2 quality specifications against the realisation of integrity and operational threats (e.g. corrosion/acid drop-out) has been acknowledged as far back as 2010, as part of initial European CCUS initiatives, and much testing has been conducted since to identify safe impurity limits; yet the latter remains an ongoing challenge. While much test data has been published, the actual implication of these over a pipeline life cycle, and the bridge from testing to actual engineering, is somewhat not well addressed and documented to steer integrity management planning. In addition, different testing approaches have often been used, making difficult to explain unexpected and sometime contradicting results. Reviewing key test parameters, experimental test procedures, and available test data in light of corrosion science and engineering insights, this paper discusses the actual credibility and severity of internal corrosion risks, which could arise against various stages or scenarios of the pipeline operational cycle e.g. commissioning, ‘in - specification’ operations, severity and number of upsets, response time to upsets. Key inherent challenges, gaps and uncertainties will be highlighted.