Protective Iron Carbonate Films—Part 3: Simultaneous Chemo-Mechanical Removal in Single-Phase Aqueous Flow

The service life of mild steel equipment found in the oil and gas production and transportation industry is often conditional on the viability of protective iron carbonate films. Once deposited on steel surfaces as by-products of the carbon dioxide corrosion process, their integrity may be severely affected by the influence of mechanical and/or chemical film removal. In this work, the investigation of simultaneous chemo-mechanical film removal has been undertaken to shed more light on the underlying conjoint mechanism. In addition, it provided the necessary information for the trilateral comparison with existing, available data on decoupled, single removal mechanisms. A rotating cylinder geometry has been utilized to create highly turbulent, undersaturated flow conditions at two Reynolds numbers (Re = 1.29 × 105 and 1.84 × 105) and pH 5.8. Film removal rates were followed by using the linear polarization resistance technique, while the film damage assessment was carried out by means of scanning electron microscopy. The findings clearly confirmed the correctness of the hypothesis on the synergism between the mechanical and chemical film removal mechanisms in single-phase flows. A likely mechanism was formulated for the simultaneous chemo-mechanical film removal process.