HISTORY OF DUCTILE IRON

Ductile Properties

  • Grey Iron is being  produced since hundreds of years. In 1948,  a major  event  occurred  when  small amount of magnesium were added to molten cast iron. It was found  that the Flaky Graphite were changed to spheroidal shape,  accordingly all mechanical properties  of  the  metal were changed, the new metal is called Ductile Iron.

ADVANTAGES OF DUCTILE IRON PIPES

  • High  tensile  strength,  good elastic module and excellent ductility, making it suitable for high stress applications and where pressure surge may be experienced.

  • Ductile iron pipes has high corrosion resistance.

  • Excellent hydraulic flow.

  • High working pressure containing to other types of pipes.

  • Ease of installation.

  • Long lifetime.

  • Can Accommodate ground movement.

 

MAIN APPLICATIONS OF DUCTILE IRON PIPES

  • Drinking and irrigation water.

  • Fire fighting systems.

  • Transmission of gas & fuels.

---- for other uses please consult SADIP.


In previously used grey Iron the carbon was present in flake form, rendering the material brittile

 

 


In ductile iron the graphite particles appear as small spheres, eliminating any risk of crack propagation. The material is no longer brittle. It is strong and ductile.


irrigation system

DUCTILE IRON, REMARKABLE MECHANICAL PROPERTIES

Mechanical Properties Symbol Unit Value
Pipes Fittings

1. Minimum Tensile Strength

 Rm Mpa 420 400
2. Minimum Yield Strength Rp0.2 Mpa 300** 300
3. Minimum Elongation at break A (%) 10 5
4. Maximum Hardness   HB 230 250

The following values generally given for ductile iron and used for calculation purposes.

Mechanical Properties Symbol Unit Value
1. Density Þ Kg/m3 7050
2. Modulus of Elasticity E* Mpa 170000
3. Poisson's Ratio V* - 0.28
4. Thermal Expansion co-efficient infinity - 11.5X10-6K-1
5. Roughness Equivalent *** co-efficient (water transfer) K* - 0.03mm (single pipe) 0.1(for single main)
6. Corresponding Value for Hazen C* - 147 for single pipe
Williams Formula   - 138 for the main

*These values are not defined by ISO standard consequently they are not committed contractually.

**270 Mpa are allowed with a elongation at break is greater than 12%.

***For further details regarding roughness of D.I. pipes, please consult SADIP

Torsion of a Strip

Deformation of a small DN Pipe under external loading.