What is Ductile Iron? Ductile iron is a remarkable engineering material that has replaced gray (cast) iron due to its strength and bendability. It is produced by treating low-sulfur molten iron of proper chemical composition with magnesium. The reaction with magnesium allows the excess carbon (graphite) present in the iron to form as round nodules or spheres. The nodular graphite, along with the proper heat treatment, allows ductile iron to have strength characteristics similar to mild steel including excellent tensile strength, impact resistance, and beam strength. These properties along with ductile ironâ€™s inherent corrosion resistance make it the material of choice for water and wastewater applications.
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Pressure Class Pipe vs.
P D F (5 7 KB)
Thickness Class Pipe Requirements f or Field
P D F (6 3 KB)
Cutting Ductile Iron Pipe
Tensile Strength & Impact Resistance
Pipe made from ductile iron (DIP) is able to withstand heavy external load-induced stresses caused by earth and heavy surface weight. Internally, DIP is subjected to high liquid pressures and water hammer, and manufactured with the following minimum mechanical properties: 60,000 psi tensile strength 42,000 psi yield strength 10% elongation. DIP has the impact resistance to withstand damage caused by improper handling, heavy external loading and abnormal service or soil conditions. It will excel in these conditions where other pipe materials fail. Bursting & Beam Strength
The strength and elastic properties of DIP provide excellent bursting strength for high pressure applications. It has the added safety to protect against water hammer. The inherent ductility and strength characteristics of DIP allow it to bend considerably prior to failure. The superior strength and toughness of ductile iron provides a greater margin of safety against service failures due to ground movement and beam loading. These properties provide unique advantages when using DIP for applications such as long-span installations on piers or supports. C orrosion Resistance
Many water utilities in the United States have utilized underground gray iron installations that have served for over 150 years. Extensive testing has shown that DIP has equal or greater corrosion resistance compared with grey iron. In most soils, ductile iron pipe requires no corrosion protection. When highly corrosive soil conditions are encountered, DIP can easily be protected with polyethylene encasement.