Why does Ductile Iron pipe have superior corrosion resistance over typical steel pipe?
The superior corrosion resistance of Ductile Iron pipe is a result of the external zinc layer (200 g/m2 minimum) and acrylic barrier topcoat applied over the zinc. The zinc is sacrificial to the Ductile Iron pipe, while the topcoat acts as an additional protective layer. The interior surface of water piping is lined with a thin layer of cement-mortar to eliminate internal pipe corrosion within the normal ranges of water pH. (Air piping uses an epoxy lining.) The entire pipe is essentially sealed from the normal influences of internal and external corrosion. This combination of external coatings and internal linings results in the long life of the pipe.
