Corrosion Behavior of BG90H Heavy Oil Thermal Recovery Tube under Different Corrosion Conditions

By simulating the process of heavy oil thermal recovery with dry air corrosion, wet air corrosion and corrosion in H2S and CO2 concomitant environment, the corrosion behavior of thermal recovery of heavy oil tube of BG90H steel was investigated. The results show that the uniform corrosion rate of BG90H steel in dry air was less than that in wet air, and the localized corrosion (pitting corrosion) appeared obviously in humid air. Wet air is rich in water vapor which leads to dew formation and uniform film on the surface of metal material. And with enough oxygen, a significant increase of oxygen absorption corrosion on BG90H steel was obviously observed. Since the increasr of the number of corrosion cells on the surface beneath the complete liquid membrane, the pitting corrosion was evidently worsening. In the H2S and CO2 concomitant environment, the maximum corrosion rate appeared at 120 ℃ and the corrosion product film was loose, porous and thick. The localized corrosion was more serious at the temperatures of 100－120 ℃and higher than 180 ℃, but slight at 150－180 ℃. The corrosion process was controlled alternatively by CO2 and H2S.