Differences in types of iron The water works representatives tell me that cast iron pipe is no longer manufactured for water service, and I need to specify ductile iron pipe. What is the difference?
Cast iron is a commonly used term to describe many types of iron. The word “cast” simply identifies the method used to produce the finished product, and not to describe the material itself. The casting method involves pouring the iron in a molten or liquid form into a mold which defines the shape of the finished product. Irons are also sometimes identified by color or physical properties. The most common iron is gray iron (the color of the iron once it has cooled). Cast iron soil pipe and fittings are produced from this type of iron. Cast iron tubs, drains, many iron body valves, fire hydrants, automotive engine blocks, brake drums, manhole covers and wrecking balls are also made of this type of iron. Ductile iron is a form of cast iron in which the addition of magnesium to the gray iron mixture in its molten state reforms the graphite flakes (which occur in gray iron) into nodular shapes. While it is true that “gray” cast iron water pipe is no longer manufactured, ductile iron is stil
