Top-of-Line Corrosion Behavior of X80 Pipeline Steel in Sour Crude

Corrosion coupon testing and scanning electron microscopy (SEM) were used to research the top-of-line corrosion (TLC) behavior of X80 pipeline steel in sour crude oil with different sulfur contents at different temperature differences. The results show that with the increase of concentration of S2-, X80 steel corrosion rate increased firstly and then decreased. When the temperature difference was in the range of 20-70 ℃, the corrosion rate exhibited a trend of increase followed by decrease. The corrosion rate was maximum at the temperature difference of 40 ℃. Uniform corrosion and a very dense and thin FeS2 layer were found at the top of the pipe. When the temperature difference was low and the condensation rate of steam was high, a thicker and more porous outer layer formed on its surface.