How to Compare Ductile Iron Pipe to Cast Iron Pipe

Pick up a sample each of the ductile iron pipe and the cast iron pipe. Ductile iron pipe feels lighter in weight than the cast iron pipe, and this difference is mostly due to the way the two pipes are manufactured. You might need to contact an engineer working with pipes, your local water company's communications department or the Ductile Iron Pipe Research Association to obtain examples of each type of pipe for a school project.

Note the composition of each sample of pipe. Ductile iron pipe is stronger and tougher than cast iron pipe. The two pipes have similar chemical components, but the ductile iron pipe is made with more magnesium, which strengthens the pipe. Instead of the flake-like iron graphite components of the cast iron pipe, the ductile iron pipe features iron graphite that is more nodular and therefore reinforces the pipe.

Recognize the modern benefits of ductile iron pipe when compared to cast iron pipe. Ductile iron pipe is used in most modern water systems because it is better able to handle extreme weather, such as below-freezing temperatures. Industry experts say that ductile iron pipe is equal to or better than cast iron pipe in resisting corrosion over time. Both pipe systems, however, are known to last more than 100 years.

Consider the linings of the two pipes. Ductile iron pipes often have cement-mortar linings that help protect the pipes from corrosion caused by chemicals in the soil and from weather. Cast iron pipes do not have linings. The Ductile Iron Pipe Research Association notes that linings are not always required. Cast iron pipes have survived for more than 100 years without linings. When deciding between the two, ductile iron pipes provide an extra layer of protection.