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 fi lms. Once deposited on steel surfaces as by-products of the carbon dioxide corrosion process, their integrity may be severely affected by the infl uence of mechanical and/or chemical fi lm removal. In this work, the investigation of simultaneous chemo-mechanical fi lm 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 fl ow conditions at two Reynolds numbers (Re = 1.29 × 10 and 1.84 × 10) and pH 5.8. Film removal rates were followed by using the linear polarization resistance technique, while the fi lm damage assessment was carried out by means of scanning electron microscopy. The fi ndings clearly confi rmed the correctness of the hypothesis on the synergism between the mechanical and chemical fi lm removal mechanisms in single-phase fl ows. A likely mechanism was formulated for the simultaneous chemo-mechanical fi lm removal process.