Co2 corrosion inhibition of X-120 pipeline steel by a modified imidazoline under flow conditions

A study of the effect of flow conditions on the performance of a carboxyethyl-imidazoline as CO2-corrosion inhibitor for API X-120 pipeline steel has been evaluated. Testing techniques include polarization curves, linear polarization resistance, electrochemical impedance spectroscopy and electrochemical noise measurements under stirred conditions (0, 250, 500, 1000 and 2500 rpm). All these techniques show that for the uninhibited solution, corrosion rate increases with an increase in the rotation speed, but for the inhibited solution, the lowest corrosion rate is obtained at 500 rpm, and it increases at lower or higher rotation speeds.

► In this work we have used X-120 pipeline steel is immersed in a CO2-saturated 3% NaCl solution at 50 °C. ► We have added 20 ppm of carboxyethyl-imidazoline. ► The solution has been stirred at 0, 250, 500, 1000 and 2500 rpm. ► Corrosion rate increases with an increase in the rotating speed. ► For inhibited solution, the lowest corrosion rate is obtained at 500 rpm.