Empirical models for long-term localised corrosion of cast iron pipes buried in soils

ABSTRACT

Empirical models are proposed for the progression of maximum depth of localised corrosion of cast iron pipes, based on data for pipes buried in 67 different backfill clay and sandy soils for up to 129 years. Early corrosion increases with increased inhomogeneity of the backfill soil and with greater availability of free water at the soil–pipe wall interface. Longer term corrosion is correlated with free water availability and occurs at a much slower rate. In most cases, the free water is fresh, oxygenated rainwater, known to be corrosive, but may also include some groundwater. Statistical uncertainty in pit depth is estimated and factors are proposed to allow for different annual rates of precipitation.

KEYWORDS:

• Cast iron
• soils
• corrosion
• localised
• long-term
• modelling

Acknowledgements

The research reported herein was a component of the Critical Pipes Project, supported by a consortium of Australian Water utilities Sydney Water Corporation, Melbourne Water, Water Corporation (WA), South Australia Water Corporation, South East Water, Hunter Water Corporation and City West Water, together with UK Water Industry Research Ltd. and the Water Research Foundation of the USA. The authors acknowledge the research support provided by this project and in particular that of Dr Matt Dafter, now with HunterH2O, Dr David Nicholas, formerly of Hunter Water Corporation and Mrs Jeya Rajalingam of Sydney Water Corporation.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Robert E. Melchers http://orcid.org/0000-0002-1068-4368

Robert B. Petersen http://orcid.org/0000-0002-9548-3097

Additional information

Funding

This work was supported by Sydney Water Corporation: [Grant Number NA].