A systematic study on pipeline steel degradation due to erosion-corrosion containing sand in CO_2 saturated environments has been carried out in a liquid-solid impingement system. This work focuses on the total material loss, corrosion, erosion and their interactions (synergy) as a function of environmental parameters (temperature, flow velocity and sand content) which enables the critical conditions between flow induced corrosion and erosion-corrosion to be determined. The experimental results show the effect of the synergistic effect (defined as the influence of corrosion on erosion) is significant and is the main reason why prediction of erosion-corrosion deviates from established CO_2 corrosion models. An empirical mathematical model is derived which in addition to predicting the thickness loss, assesses the dominance due to corrosion-related processes to assist in understanding the erosion-corrosion processes.
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