Correlation Model for the Corrosion Rates of Buried Cast Iron Pipes

Abstract

Researchers have extensively used simulated soil solutions for investigating corrosion of buried ferrous pipes. However, the literature on the correlation between corrosion rates of pipes in soil and simulated soil solution is very limited. The current paper addresses this gap and presents a model for the correlation of corrosion rates of cast iron in soil and its simulated soil solution using the test results obtained from specimens buried in soil and simulated soil solution of varying pH-controlled for 365 days. The test setup for the specimens in soil closely mimicked the buried environment, while the simulated soil solution was developed using the composition of natural soil. The same three pH values were selected for soil and simulated soil solution test setup. Apart from corrosion rates determination, the quantitative analysis of the corrosion products was performed for the specimens in varying pH environments. Based on corrosion rates measurements, a model for the prediction of corrosion rates of the specimens in the soil as a function of corrosion rates in simulated soil solution, pH, and time was developed. Moreover, detailed statistical analyses, i.e., Pearson correlation, normal distribution, homoscedasticity, correlation, and collinearity statistics, were performed using IBM SPSS Statistics to further interpret the results. The findings of this paper have practical significance for evaluating corrosion assessments of buried pipes in support of service life prediction analysis.