Classification of major cohorts of Australian pressurised cast iron water mains for pipe renewal

Cast iron pipes buried between the 1860s and 1980s still account for a significant proportion of the Australian water transmission network, and failure rates of cast iron trunk mains have risen in the past decades. In Australian cities, the manufacturing methods and corrosion mitigation techniques used in cast iron pipes are strongly correlated with the pipeline burial year. This paper introduces an approach to summarise the remaining in service cast iron trunk mains into several cohorts, in order to identify the critical pipelines with high potential of longitudinal fracture in pipe barrels. Despite the various manufacturers and casting moulds used in Australian cast iron pipes, two major cohorts, static and spun cast iron pipes, were identified based on manufacturing methods, material properties, microstructural analysis and wall thicknesses. A statistical analysis confirmed that spun cast pipes have higher burst rates and relatively short life spans than statically cast pipes, evidently due to thinner wall size.