The results of a metallographic study of gray cast-iron water pipes are reported. These pipes were installed between 1885 and 1973 in eight different water systems. Each pipe had been extracted during scheduled maintenance or failure repairs to provide data for a larger study to produce a methodology for determining the residual life of gray cast-iron pipes. This metallographic study was conducted to determine the causes of vari- ations in the mechanical properties of these pipes. Pit-cast and spun-cast pipes were found to have distinctly different types of graphite flakes, flake sizes, and metallic matrices.
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