Corrosion and protection of mild steel in petroleum distillates - Electrolyte mixtures

The purpose of this study is to examine the influence of water and salts present on the corrosion process in petroleum distillate - electrolyte mixtures and evaluation of inorganic inhibitors efficiency for protection of mild steel in these mixtures. Most of the research in this area until now was done with hydrocarbon - water mixtures with relatively high concentrations of water (above 5% volume). This study was conducted using mixtures of light petroleum distillates (naphtha and gasoline) and water with water concentrations in the mixture below 5% volume. The study confirmed the electrochemical origin of the corrosion mechanism and showed that the main cause of the corrosion in the petroleum distillate - water mixtures is the presence of water and dissolved oxygen. Critical added water concentrations were evaluated for naphtha-water and gasoline-water mixtures. The most efficient concentrations of inorganic inhibitors were determined and the inhibition mechanism was confirmed. Valuable data regarding different types of corrosion attack (pitting or uniform corrosion) on mild steel in petroleum distillate - electrolyte mixtures was acquired during the study.