J. M. Makar

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 variations 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. These differences were directly responsible for the variations in the mechanical properties between the two types of pipes, with the larger flake sizes of the pit-cast pipes, in particular, producing weaker material. Examples of anomalous pipes that did not have the standard appearance of either type of manufacture were also found and the reasons for their appearance identified. The results of the stud...

The National Research Council Canada has recently completed a project to assist the city of Montreal in determining the condition of its water and sewer system. The National Research Council Canada staff members reviewed available and developing diagnostic techniques for both systems, conducted experiments on nondestructive evaluation methods and provided general scientific advice during the course of the project. This paper presents a review of current technologies for inspecting brick, concrete, and vitrified clay sewer systems, including the results of three experimental investigations. The results of the review are given in a tabular form that lists the applications, advantages, and disadvantages of each technique. Current and developing technologies are described that will supplement or replace closed circuit television inspection for determining the condition of sewer pipes through inspection of their internal pipe walls. In addition, techniques that allow sewer operators to investigate the pipe wall condition throughout the wall's thickness (rather than just on the inner surface) and to determine whether voids exist behind the pipe wall are described.