Study of Structural Steel Corrosion in Industrial Atmospheric Environments of Warri, Delta State

This study investigates the atmospheric corrosion behaviour of structural mild steel specimens exposed to the industrial atmospheric environment of Warri, Delta State, South South Nigeria. Warri hosts one of Nigeria's most concentrated industrial and petrochemical clusters, generating airborne pollutants including sulphur dioxide and hydrogen sulphide that create highly corrosive atmospheric conditions for steel structures. Carbon steel coupons are deployed at three exposure stations representing varying proximity to refinery and industrial emission sources. Weight loss measurements are recorded at 3, 6, 12, and 18 month intervals. Corroded surfaces are characterised by SEM-EDX, XRD, and profilometry to identify corrosion product phases and surface damage morphology. Atmospheric corrosivity is correlated with measured concentrations of airborne SO2, H2S, and chloride deposition at each station. Results confirm a classification of C4 to C5 atmospheric corrosivity at stations closest to emission sources, consistent with ISO 9223 classifications for highly industrialised environments. Corrosion products include goethite, lepidocrocite, and akaganeite, with the latter indicative of chloride-assisted pit initiation. Corrosion rates range from 80 to 210 micrometres per year. The study maps the spatial distribution of corrosion risk in Warri and recommends differentiated protective coating specifications for structures at varying distances from emission sources. Keywords: atmospheric corrosion, structural steel, industrial environment, Warri, Delta State.