- Title
- Factors involved in the long-term corrosion of buried cast iron
- Creator
- Petersen, R. B.; Melchers, R.
- Relation
- Corrosion and Prevention 2016. Proceedings of Corrosion and Prevention 2016 (Auckland, New Zealand 13-16 November, 2016)
- Publisher
- Australasian Corrosion Association
- Resource Type
- conference paper
- Date
- 2016
- Description
- The depth and rate of increase of external corrosion of old cast iron water mains buried in soil is important for predicting remaining life of water supply systems in many cities. Prediction requires good quality mathematical models, preferably based on real-world observations. Unfortunately, currently available models are inadequate as they have been shown to be inconsistent with long-term data and established corrosion science principles. To improve on this situation data of corrosion losses were reassessed and a new model for corrosion was proposed. This model was calibrated to long-term field data collected at 37 pipe exhumation sites. The analysis approach adopted is unique and is based on the notion, also suggested by Tomashov, that active corrosion in soils is wet corrosion and therefore should have similarities with corrosion under immersion and wet atmospheric conditions. Following on from this the concept of a “time of wetness” was taken from atmospheric corrosion as a way to estimate the wetness at the corroding interface. Also, the analysis considered the influence of microbiological attack being controlled by a limiting nutrient, as observed for corrosion under immersion conditions. It was found that the main factors influencing soil corrosion are, in order, time of wetness and inorganic nitrate concentration (for microbiological attack). Their influence on external penetration was also quantified. Other parameters including chloride, phosphate and carbonate content were also considered, but were found to be less important.
- Subject
- cast iron; soils; corrosion; pitting; long-term; modelling
- Identifier
- http://hdl.handle.net/1959.13/1343949
- Identifier
- uon:29282
- Identifier
- ISSN:1328-3901
- Language
- eng
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