Effect of Sulfur Content in the Crude Oil to the Corrosion Behaviour of Internal Surface of API 5L X65 Petroleum Pipeline Steel

This work discussed the corrosion behaviour of the internal surface of pipeline steel caused by petroleum products' composition, particularly crude oil. Internal and external pipeline corrosion is the notable cause of pipeline failure in Malaysia's oil and gas industry. However, internal corrosion is preferred to be concerned in this work because it involved one of the significant corrosive media in crude oil, such as sulfur content. This project aims to find the sulfur concentration in the crude oil using Fourier transform infrared spectroscopy and atomic absorption spectroscopy. The corrosion rate, corrosion current and corrosion potential of the API 5L X65 grade carbon steel pipeline in different simulated H2SO4 solution concentrations were carried out using the Tafel extrapolation technique. The samples' corrosion properties were morphologically measured through the optical microscope, scanning electron microscope, and energy dispersive X-ray analyses. The results showed pipeline steel's corrosion rate significantly increased with increasing H2SO4 concentrations. The corrosion products formed on the pipeline steel surfaces were mainly composed of iron sulphate, iron sulphide, and iron oxide. These findings are crucial to understanding the corrosion behaviour caused by crude oil and should be further investigated with the other influential factors such as temperature and petroleum flowing velocity.