Recent Progress in the Modeling of Corrosion of Structural Steel Immersed in Seawaters

For coastal infrastructure the long-term durability of new steel structures and the remaining life of existing steel structures is of central interest to their proper maintenance and asset management. This is particularly the case where protective measures such as paint coatings, galvanizing, or cathodic protection will become or are already ineffective or are nonexistent. Guidelines currently available for new design and for assessment are largely empirical and have a high degree of uncertainty. To address this recent research has produced better quality models for the progression of corrosion with time. These employ fundamental characteristics of steel corrosion as obtained from actual field observations and from laboratory-based electrochemical and other observations. The models are reviewed herein and an illustrative application to a typical infrastructure component is presented. It is shown that seawater temperature has an important influence on the rate of early corrosion and also has longer-term effects not predicted by short-term observations. Also, the influence on corrosion of small changes in metal composition and in water velocity, salinity, and pollution are described.