Articles

Ductile Cast Iron vs Steel

By August 7, 2018 No Comments

The ductile cast iron has a great advantage over steel: it is moldable.

Blast furnaces produce heavy steel ingots as the final result. These ingots are treated in cold or hot by mechanical means, such as rolling and stamping. Through this procedure it is very expensive to get complex shapes using steel, but it is easy to get plates, beams, wire and so on, which are usually the final products of steel.

However, the iron castings are so fluid that it is possible to fill molds with the liquid iron itself, so it is possible to easily get complex shapes. Even steel pipe installations, valves or other fittings are made of gray cast iron or ductile cast iron due to their complex shapes.

LEFT PICTURE: Steel hot rolling process. | RIGHT PICTURE: Pouring a liquid casting melt into a mold.

Competitive advantages of the material: Ductile Cast Iron vs Steel

In order to manufacture the steel pipe, rolled and welded plates are used (either longitudinal, or helically) getting a cylindrical shape.On the other hand, with ductile cast iron, the liquid melt is centrifuged inside a mold that has the shape of the bell and the spigot, which gives the characteristic shape to the ends. The ductile iron pipe is unmoulded in one piece, and therefore has no welding connection.

LEFT PICTURE: A steel pipe with helical welding, made of a steel plate. | RIGHT PICTURE: A ductile iron pipe (bell in the foreground), in one piece.

Benefits and advantages applied to the ductile iron pipe

  • The own resistance of the ductile cast iron withstands very high pressures.
  • Very high installation ratio minimizing the risk of pipe damage during installation.
  • Earthquake resistant: Protection against terrain movements and unstable soils.
  • Larger inner diameter = Higher hydraulic capacity
  • Installation with or without trench

Advantages of the hydraulic design: Steel pipe vs Ductile iron pipe

Comparison of installation costs: Welded Steel vs Lok&Play® restrained joint system