Scrutiny of the Corrosive Strength of Crude Oils on the Destruction of Ferrous Metals

Ferrous metals play a dominant role in the industry of crude oil refining industry by covering basic units and essential equipments since facing some adverse impacts from such crude oils due to their corrosive composites especially sulfur compounds, organic acids and salts. By referring the recent references and results there were expected to investigate the nature of the corrosion of seven different types of ferrous metals that applicable in the industry of crude oil refining industry due to the impacts of elemental sulfur, Mercaptans, organic acids and salts that presence in crude oils since the occurrences of such crude oils. According to the requirements and considering the availability seven different types of ferrous metals and two different types of crude oils were selected as the samples. The elemental sulfur contents, Mercaptans contents, acidities, salt contents and also the chemical compositions of selected ferrous metals were tested by in order of XRF analyzer, titration methods, salt analyzer and digital XRF detector. A set of similar sized prepared metal coupons were immersed in both crude oil containers separately as three homogeneous metal coupons per each crude oil container. The corrosion rates of each type of metal with respect to each crude oil type were determined by the immersed metal coupons in order of after 15, 30 and 45 days immersion periods. As the further analysis the surfaces of corroded metal coupons, decayed ferrous and copper concentrations from metals into crude oils and the variations of the initial hardness of metal coupons were analyzed by in order of optical microscope, atomic absorption spectroscopy (AAS) and the Vicker’s hardness tester. Basically there were found the higher corrosive protection regarding the stainless steels when comparing with other metals especially having at least 12% of chromium and sufficient amounts of nickel, approximately higher contribution of salts in the metallic corrosion, improper progress of sulfur compounds in the metallic corrosion, formations of FeS/CuS, rarely Fe2O3, corrosion cracks and pits on the metal surfaces, significant decays of ferrous during the corrosion, massive decays of copper from some metal which showed higher corrosion rates excluding stainless steels and the slight reductions of the initial hardness of most of metals due to the corrosion.