Long-term immersion corrosion of steels in seawaters with elevated nutrient concentration

•Bi-linear model for long-term immersion corrosion of steel in seawater is proposed.•Parameters describing model calibrated against multiple sources of literature data.•Model allows for data uncertainty and seawater temperature.•Greater dissolved inorganic nitrate concentration increases immersion corrosion loss.

Data from a variety of field exposure programs is used to quantify the effect of concentration of dissolved inorganic nitrogen (DIN) on long-term seawater immersion corrosion loss of structural steels. A linear correlation model that asymptotes the long-term part of the previously proposed bi-modal corrosion loss model is used. It allows for average seawater temperature. Model parameters and their variability are determined and reported. The model permits prediction of long-term corrosion loss in nutrient polluted waters of known average temperature. An example shows that anthropological pollution of seawater potentially is a major hazard for corrosion of steel infrastructure.