Pipeline corrosion occurs due to several reasons which consist of physical, chemical, and environmental factors. The physical factors are structural (material properties, crevices, inclusions, etc.) and product (temperature, pressure, flow rate, flow pattern, etc.) properties. However, chemical factors are controlled by pH, dissolved solids, gases (H2S and CO2), and microorganisms. Environmental factors are the most essential factors which consist of oilfield composition, soil composition, moisture level, and nature of the working area. Internal corrosion especially flows accelerated corrosion is a crucial issue in a fitting area of the pipeline steel network. Flow accelerated corrosion (FAC) is defined as accelerated corrosion by the turbulent fluids flow over a surface, which promotes mass transfer and enhances the dissolution and thinning of protective films in carbon steel pipes. FAC is the major reason for steel pipeline failure in the oil and gas industry. Pipe fittings such as elbow, tee, and reducers often undergo failure when they are subjected to corrosive environments under turbulent flow conditions. FAC of API steel depends on hydrodynamic parameters of the fluid flow such as wall shear stress and flow velocity. Corrosion current density for all the located specimens at the intrados and the extrados of the elbow are found to be increased however, charge transfer resistances were significantly decreased along the fluid flow path.
Keywords: Corrosion, flow accelerated corrosion, corrosion current density, metallic passivity.