An in-situ investigation of CO flow-induced corrosion and erosion-corrosion of UNS K03014 pipeline materials using combined acoustic emission and LPR methods

A method based on count rate and energy of measured acoustic emission (AE) signals has been implemented to investigate flow-induced corrosion and erosion-corrosion of UNS K03014 carbon steel. The specimen's corrosion behavior under the submerged impinging jet (SIJ) in a CO saturated oilfield process brine at constant temperature of 50 oC was assessed for different flow velocities (7, 10, 15 m/s) without sand for flow-induced corrosion and with sand (50, 200, 500 mg/L) for erosion-corrosion. AE signal count rate during each test was measured and analyzed simultaneously with the corrosion rate from linear polarization resistance (LPR). The results show a good correlation between AE count rate and corrosion rate in each test; and that AE count rate increases with increase in corrosion rate as flow velocity is increased for flow-induced corrosion as well as increase in sand loading for erosion-corrosion which is an indication that flow-induced corrosion and erosion-corrosion mechanisms are sources of AE signals. The suitability of the AE technique in monitoring flow-induced corrosion and erosion-corrosion was further assessed by adding 100 ppm high shear film forming corrosion inhibitor at 10 m/s flow velocity and a considerable reduction in AE count rate and corrosion rate was observed.