With the view to developing such a more realistic model, in the following paper a review is given of cast iron corrosion, the processes occurring during cast iron corrosion in soil and the external soil factors that influence the corrosion process. This is followed by an outline of the proposed approach to modelling long-term corrosion of cast iron pipes. An outline is given also of the field data collection requirements for calibration of the model.
Iron corrosion is one of the most complicated and costly problems facing water utilities. Unlike metal piping, PVC pipes won't rust or corrode over time because it does not react with air and water the way metal does, which results in a significantly longer lifetime of the pipe.
The major finding of the study is that PVC pipe has the lowest overall failure rate when compared to cast iron, ductile iron, concrete, steel and asbestos cement pipes. Another major finding concludes corrosion is a major cause of water main breaks: 75% of all utilities have corrosive soil conditions and combined with a high portion of old cast iron and ductile iron pipes, corrosion is ranked the second highest reason for water main pipe failure.
This study published by the Utah State University (USU) buried structures laboratory takes a comprehensive look at PVC pipe excavations, testing and life cycle analysis. The key findings? A combination of pipe examination and testing data in conjunction with previous pipe break studies support PVC's longevity in excess of 100 years.
Infiltration into leaking pipes is a problem of growing concern to geotechnical and environmental engineers. Adverse effects of pipe leaking include groundwater contamination and soil erosion into cracks, holes and joints. It has been reported that soil erosion can lead to significant stress changes around pipes. The experimental results presented in this study provided an insight into understanding this important soil-structure interaction problem.