Comparison of the Mechanical Properties of Steel and Ductile Iron Pipe Materials

Water infrastructure engineers commonly evaluate a variety of pipe materials to determine the most appropriate solution for a particular application. Occasionally engineers inappropriately apply identical structural design criteria for both steel and ductile iron pipe (DIP). While similarities do exist, there are substantial differences in the material properties that make their structural designs unique. The applicable AWWA standards and design manuals are evidence of such variances. To demonstrate the distinguishing mechanical properties of steel and ductile iron, large diameter samples were gathered, cut, and subjected to mechanical property testing. A review of the results will validate the existence of distinct material properties and clearly indicate the need for unique design practices that should not be modified or comingled. The mechanical property differences between steel and ductile iron and the implications to applicable AWWA design criteria are discussed.