Assessment of Residual Tensile Strength on Cast Iron Pipes

Criteria for rehabilitation priority are an important factor in planning the improvement of water supply systems. In this study, deteriorations of water pipes are discussed to evaluate structural stability of deteriorated cast iron transport and transmission pipes. For the purposes, safety factor is introduced and estimated by measuring tensile strength and analyzing stress caused by the internal-external loads working on buried pipe body. Prediction models of a residual tensile strength are presented using pit characteristics and fracture toughness. Related information is surveyed and collected in the fields up the pipe by digging and assessing its structural stability. The collected data is analyzed to evaluate the deterioration degree of the pipes including corrosion and pitting characteristics, fracture toughness, installation environment and water qualities etc. Assessment models developed in this study showed a little correlation for measured residual tensile strength. The results will very help water utilities to manage water pipes in the aspect of rehabilitation and assessment of structural safety.