Fluid flow effects on CO2 corrosion: a review of applications of rotating cage methodology

Abstract

Purpose Among the many influencing effects that the medium has on the CO2 corrosion of carbon steel, flow is one of the most important because it can determine the formation of corrosion product scales and its stabilisation, thus influencing the attack morphology and corrosion rate. This paper aims to summarise some factors affecting aqueous CO2 corrosion and the laboratory methodologies to evaluate one of the most important, the flow, with an emphasis on less costly rotating cage (RC) laboratory methodology. Design/methodology/approach Regarding the key factors affecting CO2 corrosion, both well-established factors and some not well addressed in current corrosion prediction models are presented. The wall shear stress (WSS) values that can be obtained by laboratory flow simulation methodologies in pipelines and its effects over iron carbonate (FeCO3) scales or inhibition films are discussed. In addition, promising applications of electrochemical techniques coupled to RC methodology under mild or harsh conditions are presented. Findings More studies could be addressed that also consider both the salting-out effects and the presence of oxygen in CO2 corrosion. The RC methodology may be appropriate to simulate a WSS close to that obtained by laboratory flow loops, especially when using only water as the corrosive medium. Originality/value The WSS generated by the RC methodology might not be able to cause destruction of protective FeCO3 scales or inhibition films. However, this may be an issue even when using methodologies that allow high-magnitude hydrodynamic stresses.