Factors Affecting Corrosion of Buried Cast Iron Pipes

Abstract

Although corrosion of metal in soils has been intensively investigated in the past, a review of the published literature shows that limited research has been undertaken to understand how soil properties affect the corrosion behavior of cast iron pipes, owing to the scarcity of the reported information on buried metal corrosion in its backfill soil condition. In this paper, a methodology is proposed to statistically analyze the effects of soil properties on corrosion behavior, and a comprehensive and long-term historical corrosion database of buried cast iron pipes is thoroughly interpreted. The corrosion is characterized by two time-independent parameters in each sample, that is, the proportionality (k) and exponent (n) factors of the power law model. It is found that the exponent factor n of power law model is closely associated with the level of soil aeration. It is also found that grouping corrosion data based on soil aeration produces stronger correlations between soil properties and corrosion rates compared with that when taking all soil samples as a whole. The authors conclude that an appropriate classification of soils can benefit the identification of key factors influencing corrosion of buried cast iron pipes at different exposure times. This research provides further knowledge for asset managers and engineers to accurately predict the failure of corrosion-affected cast iron pipes.