Comparative study on the effect of NaNO2 in corrosion inhibition of micro-alloyed and API-5L X65 steels in E20 simulated FGE

Abstract

The effect of sodium nitrite (NaNO2) in the corrosion inhibition of micro-alloyed and API-5L X65 steels in E20 simulated fuel grade ethanol (SFGE) have been investigated via gravimetric method and morphological examination. While NaNO2 addition may positively slow down corrosion rate, its concentration within the tested range of 0.2 – 1.0 g/L plays an insignificant role in improving the corrosion resistance of API-5L X65 and micro-alloyed steels. Morphological examination of both steels after immersion tests in the presence and absence of the inhibitor showed pitting corrosion mechanism. Furthermore, statistical analysis confirms with 90 % confidence, that there is no significant difference between the corrosion behaviour of the two steels in E20 SFGE with and without NaNO2 inhibitor. Highest protection of the metal surface was achieved at 62.63 % with 0.2 g/L NaNO2 for API-5L X65 in E20.