The Cause of Metallic Corrosion in Crude Oils

Metallic corrosion is a severe interrogation regarding most of industrial applications of metals such as the industry of crude oil refining because of the foremost role of metals. The term of corrosion is usually explained as the formation of the metal oxide, sulfide, hydroxide or any compound related with a carboxylic group on the surface due to the impact of the surrounded conditions. The content of sulfur, acidity, mercaptans and salt content are the well ascertained corrosive properties of crude oils also the chemical composition of metals acquit oneself the fundamental preface for the corrosion. The surveillance of the comparison of corrosive capabilities of Murban and Das Blend crude oils in front of seven different types of ferrous metals that used in Sri Lankan refining industry was the dominant intention of this research. The chemical composition of used metals were determined by XRF detector while testing the contents of sulfur, acidities, contents of mercaptans and salt contents with respect to both crude oils simultaneously. Batches of well cleaned and equal sized metal pieces were immersed in both crude oils separately and the corrosion rate of each type of metal piece was determined after 15, 30 and 45 days from the immersion by weight loss method under the observations through the optical microscope. The ferrous and copper concentrations of each crude oil sample were tested while testing the variation of the hardness of each metal as a confirmation stage. According to results there were found relatively higher amount of sulfur, mercaptans, acids and lower amount of salt in Das Blend than Murban although relatively higher corrosion rates of most of metals in the Murban than the Das Blend. The slight reduction of hardness in each metal piece was found while observing significant concentration of ferrous and copper from some of crude oil samples.