The Institute for Research in Construction (IRC) has undertaken a three-year collaborative research project with the American Water Works Association Research Foundation to build a new understanding of the effect of corrosion pitting on gray cast-iron pipes used in water systems. ("Gray" refers to the color produced by the graphite flakes in the cast iron, which can be seen along the broken surface of these pipes manufactured between 1850 and the early 1970s.)
Each year, cities in Canada and the United States experience thousands of failures in small, gray cast-iron pipes. Over 80 percent of these failures occur when the pipes crack across the center, which is similar to the way in which a twig breaks when it bends.