MODIFICATION OF CARBON STEEL SURFACES TO REDUCE CORROSION FOULING IN OIL GAS INDUSTRY

摘要

The scope of the present work was to investigate the influence of surface properties of carbon steel substrates on sweet corrosion (CO_2 Corrosion), since this type of corrosion is responsible for more than 60% of in-service failures in the oil & gas industry. Surface treatment techniques applied to the test samples are Composite Coating, Ion Sputtering (Magnetron and Unbalanced Sputtering), Ni-S-P and Ni-P-PTFE Coating. Twenty-two pairs of carbon steel electrodes and the same number of flat carbon steel plates have been coated with these techniques and used for this study. Other process parameters such as temperature, and solution composition were kept constant in order to allow comparison between the different surface treatments. Surface energy and surface roughness measurements were carried out to characterise the treated surfaces. The weight of the samples was measured before and after the tests to identify the corrosion rates. So called 'Bubble Tests' have been used to perform the experiments; in these tests the polarisation resistance could be measured and subsequently converted into corrosion rate. Very promising results have been obtained, indicating a weight loss of the treated samples of less than 1% of the weight loss of untreated carbon steel specimens, with more than half of the treated specimens achieving the target of a corrosion rate below 0.1 mm/year.