Corrosion Status and Corrosion Mechanism of a Long-Term Service Submarine Pipeline

In order to study the corrosion status and corrosion mechanism of a submarine pipeline which had been in service for 22 years, a typical tube section was chosen for observation of corrosion macrograph and corrosion product analysis by X-ray diffraction (XRD). The results show that the corrosion of the inner wall of the tube section was dominated by uniform corrosion. Although there was serious scaling phenomenon in the inner wall, no corrosion under the scale was found. The corrosion of the outer wall of the tube section was slight, and bacterial corrosion happened in the annulus space.