Abstract
Corrosion Under Insulation (CUI) is one of the most significant corrosion issues in oil and gas production facilities. One way to address this issue is to use insulation materials with corrosion inhibitors. In this study, under the simulated CUI conditions in the laboratory, the performances of some corrosion inhibitors were evaluated on carbon steel. Immersion tests of polished metal surface specimens and corroded ones were conducted in the solutions controlled 18,000 ppm chloride ions (3.0 wt.% NaCl) at 50°C, and the mass loss values were compared. In addition, potentiodynamic polarization measurements were performed to presume these inhibition mechanisms. One nonflammable inhibitor known to contain phosphates and nitrites showed good anti-corrosion performance on both the polished metal surface specimens and the corroded ones. The primary inhibition mechanism was considered to be the formation of the protective film on the steel surfaces. On the other hand, it was deemed that localized corrosion was a possible concern in spots where the inhibitor did not act sufficiently. Therefore, applying corrosion inhibitors to insulation materials is expected to be one of the corrosion control techniques for preventing further CUI as a temporary expedient until other permanent repairs are carried out.
