Ageing behaviour

Last updated on Mon, 02/18/2013 - 16:13

As components that are integrated in buildings, waste water and rainwater drainage systems must remain in a serviceable condition over the long term in spite of adverse operating conditions. Ageing refers to any gradual, irreversible change in a material's structure and/or composition, liable to affect its behaviour or serviceability. When a drainage material is selected, the stability of its properties ensures operational reliability over time.

Stability of cast iron mechanical properties

The ageing of a material may be due to its own instability, to environment or chemical stresses, to mechanical strains, or a combination of any of these causes.
It is an established fact that cast iron offers long service, owing in particular to the stability of its mechanical properties over time.

Cast iron is not sensitive to thermal ageing

  • Its mechanical strength remains stable
  • Its thermal expansion is very low compared to plastics.
  • Cast iron pipe systems are not liable to creep at operating temperatures.

Cast iron does not deform under mechanical strain

  • Its longitudinal stiffness, which eases bracketing and protects water stream in horizontal sections, remains intact. Its Young modulus of elasticity is ranking from 80 to 120 GPa vs 2 to 5 GPa for PVC.
  • Cast iron's tensile strength is 8 times greater than that of PVC: 200 MPa vs 25. (residual resistance, 50 years according to the standards). This property is of utmost importance in case of network overloading.
  • Its ring stiffness (cold measurement) around 700kN.m is not affected by temperature and is 87 times that of PVC pipes. It is mainly appreciated for buried pipe work.

The properties of cast iron ensure the stability of systems and long lasting operational safety.

Resistance to climatic stresses

The properties of materials are extremely important when they are stored or exposed to adverse conditions (extended exposure to ultraviolet light or wide temperature variations…).

Cast iron undergoes no structure modification under climatic stresses.