Microstructural Investigation of Graphitic Corrosion in an Approximately 150-Year-Old Cast-Iron Water Pipe

Abstract

Many cast-iron water distribution pipelines installed during the second half of the nineteenth century remain in service today, making the investigation of their long-term corrosion behaviour important from both engineering and heritage conservation perspectives. The aim of this study was to investigate the microstructural and chemical characteristics of graphitic corrosion in an approximately 150-year-old cast-iron water pipe using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), with particular emphasis on the microstructural features and formation mechanism of graphitic corrosion. The results revealed that, despite nearly 150 years of service, a substantial portion of the original pipe cross-section had been preserved. Corrosion occurred predominantly in the vicinity of the graphite flakes, where localized formation of iron- and silicon-containing oxide phases was observed. Furthermore, EDS analyses detected the presence of chlorine within the corroded regions, consistent with the graphitic corrosion mechanism reported in the literature. These findings contribute to a better understanding of the long-term corrosion processes and graphitic corrosion occurring in historical cast-iron water distribution systems.