Effect of corrosion products formed and flow rate over the surface of steels API 5L X-52 and X-70 on the rate of corrosion in brine added with kerosene and H₂S

This paper studies the effect of corrosion products formed and the rate of flow on the surface of two API steels on the corrosion rate in a brine added with kerosene and H₂S. Corrosion products formed over the surface have been characterized using Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and Linear Polarization techniques. XRD and EDS analysis showed that the corrosion products are mainly composed of a mixture of oxides (maghemite, hematite, magnetite), sulfides (mackinawite, troilite, markasite, smithite) and one sulfate (mikasaite). Across SEM micrographs the corrosion products formed are very similar, covering most of the steels surface. Linear Polarization results confirm a good behavior on the rate corrosion for both steels in a range of flow rate at 4000 to 5500 rpm but the API 5L-X70 was the best behavior in the range of 4000 to the end of the test at 6500 rpm due the presence showing a greater amount of sulfur compared to the oxides thus resulting more efficient with respect to the rate of corrosion. The protective function with corrosion products on the surface of the API 5L-X-70 steel turns out to be much better compared to the other.