Corrosion Behavior of Titanium and Nickel-based Alloys in HCl and HCl + H2S Environments

Titanium grade 2 (UNS R50400), alloy 400 (UNS N04400), alloy 20 (UNS N08020) and alloy C-276 (UNS N10276) were electrochemically explored to determine their corrosion susceptibility behavior when exposed to environments typically found on existent atmospheric column overhead systems in mexican crude oil refineries. Linear anodic polarization was used to attain electrochemical results. Main corrosive species –present in actual overhead systems for a characteristic heavy crude oil produced in Mexico- were reproduced by performing experiments in two distinct electrolytes (0.05 mol/L HCl and 0.05 mol/L HCl + 500 ppm H2S in aqueous solution) at 40 °C. Metals were examined at pH 1.5, 4, 6, 8 and 10 values for both electrolytes to identify effects of key contaminants. Results revealed that each explored metal exhibits particular corrosion susceptibility depending on pH of environment, suggesting that corrosion susceptibility of every metal is a function of particular metal-environment conditions.