Underground Corrosion of Water Pipes in Cities

This section summarizes a study to determine the causes and mechanism of water main failures. 

A total of 17 pipe failures and soil samples were studied by metallurgical and analytical evaluation and the following points have been noted. 

In almost all the failures, including failure of the service saddle on an asbestos-cement 10-inch water pipe, corrosion from the soil side was to great extent responsible for the failures. 

Loss in mechanical properties such as reduced tensile strength of cast iron pipes contributed to the pipe failures. 

The corrosion rate of ductile iron pipes in soils was in the range 0.62-2.5 mm/yr with an average of 1.11 mm/yr which is twice the rate of cast iron pipe. Failure of ductile iron pipe was solely due to localized pitting corrosion leading to pipe wall perforation. 

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