DUCTILE IRON PIPE

Although chemically similar to Cast Iron of low phosphorous content, Ductile Iron incorporates significant casting refinements, additional metallurgical processes, and superior quality control. After a desulfurizing treatment, magnesium is added, which in turn is followed by a post-inoculation treatment with a silicon base alloy. These steps cause a profound change in the manner that the carbon, as a graphite, is formed during the solidification of the iron. Instead of the interlaced flake form found in Cast Iron, the graphite develops myriads of isolated spheroids. The matrix becomes relatively continuous, thereby greatly increasing the strength, ductility and impact resistance of the metal. Its impact strength and elongation are many times greater than that of Cast Iron. Ductile Iron has a modulus of elasticity of approximately 24 million psi.

Ductile Iron pipe is a centrifugally cast product. A controlled amount of molten iron is introduced into the rotating mold, which generates a centrifugal force that holds the iron in place against the mold until it solidifies. The pipe is then removed and furnace-annealed to obtain the prescribed physical properties.

The following acceptance test requirements must be met before the pipe is declared ready for shipment: