The synergistic effect between erosion and corrosion of API pipeline in CO2 and saline medium

Erosion–corrosion is common in oil and gas processing plants and pipelines where there is interaction between solid particles, corrosive fluid and target material. The objective of the present work is to assess the synergism between erosion and corrosion of API X-70 pipeline steel under liquid–solid impingement conditions in 2 g/l NaCl solution purged with CO2 as the corrosive (acidic) media and aluminum oxide as the erodent. The total material loss rate, the components of erosion, corrosion and their synergistic interactions have been determined. The experimental results show that there is an immense correlation exists between erosion and corrosion. During erosion–corrosion, erosion enhances corrosion and corrosion enhances erosion resulting in higher material loss. Scanning electron microscopy analysis of the worn specimen reveals that plastic deformation and fracture are the dominant mechanisms during the erosion–corrosion process. Furthermore, corrosion removes the work hardened layer and exposes a stress free surface for erosion while erosion removes the passive film from the surface and creates a work hardened layer which is highly susceptible to corrosion.

► Synergism between erosion and corrosion was investigated. ► SEM observation was performed to investigate possible erosion–corrosion mechanisms. ► Combined effect of erosion–corrosion is higher than individual erosion and corrosion. ► Corrosion increases erosion by 4.6 times and erosion increases corrosion by 4 times due to synergistic effect.