An investigation on the corrosion in the dehumidification bubble caps in the gas refinery

Abstract

One of the severe challenges in the oil, gas, and petrochemical industry is associated with reducing the costs of corrosion damages by removing the oil fluids’ moisture, and humidity in the facilities. As an essential component of moisture absorption towers in the dehumidification section is the bubble cap, which loses its efficiency in a short time due to continuous contact with steam. In the present work, the causes of the destruction of a piece of bubble cap are investigated thoroughly employing visual and microstructural observation, chemical composition study through quantometer, X-ray spectroscopy (EDS) and XRD assessments, and also the corrosion behavior study by polarization and electrochemical impedance spectrometry (EIS) analysis. The mechanism and type of corrosion occurred to the bubble cap and its capability against the corrosion were assessed. The results showed that the corrosion products after service were Fe3O4, Fe2O3, Fe(OH)3, and FeCO3, which declined the microhardness from 121.3 to 99.3 Hv. The corrosion rate was found to be 0.03116 mm/y in the saline solution. The poor performance of the material against corrosion were attributed to the casting defects, and the ineffective microstructural phases, formed due to the deficient alloying elements. According to the results, some recommendations and solutions, as effective preventive ways, have been proposed to hinder corrosion, and lead to the higher durability and the lower replacement costs.