Thermally induced strains and stresses in cast iron water distribution pipes: an experimental investigation

Full-scale tests have been carried out on lengths of unrestrained and restrained plain and jointed distribution pipe sections (similar to 4 '' or similar to 100 mm internal diameter) in order to investigate the strains and loads generated in cast iron water distribution mains as a result of temperature fluctuations. Tests on unrestrained sections enabled the coefficient of thermal expansion of the pipe material to be measured. In a fully restrained situation, which can occur in a pipe section in service when the joints are locked, tensile stresses arise from a decrease in temperature ( in accordance with the predictions of a simple one-dimensional model) and it is shown that these stresses are sufficiently high to fracture a corroded pipe. In situations where the tensile stress leads to joint slippage, leakage through the joint is observed. Water leakage was also observed through the wall of corroded pipes that retained sufficient structural stability to carry load without failure