The effect of 25°C holding time of A572 in simulated SO2-CO2-O2-H2S corrosion environment of the upper deck of cargo oil tank was investigated by weight loss, SEM, XRD and electrochemical measurements. The results indicated that the corrosion behavior of A572 was general corrosion and the average corrosion rates increased sharply at first then increased slowly with the extension of 25°C holding time. When the 25°C holding time increases from 0h to 1h, the corrosion process is controlled by the electrochemical progress and the protection of the rust layer is weak. However, when the 25°C holding time increased from 1h to 3h, the reduction of the rust itself becomes dominant. When the 25°C holding time increased from 3h to 5h, the thickness of the cooling water film has little influence on the acceleration of the corrosion. The increased amount of Fe3O4 and Fe2O3 indicated an improved resistance of the rust. The rust enhances initially and then stabilizes the cathodic process, but the anodic process tends to be further inhibited.

Subject
X-ray diffraction, Water, Steel coupons, Average corrosion rates, Polarization curves, Corrosion products, Bubbling, Corrosion morphology, Steel, Rust, Corrosion mechanisms, Risk reduction, Oil
Keywords:
mechanism, electrochemical measurements, corrosion behavior
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2014
Association for Materials Protection and Performance (AMPP)
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