Merits: High strength and ductility resulting in light weight. Jointing easy with mechanical or (in large sizes) welded joints.
Disadvantages: Requires careful protection against external and internal corrosion.
Merits: Modern ductile iron pipes have strength and ductility approaching those of steel. Push-fit joints are easy to make. The pipes are cast in an automatic machine to obtain light but strong walls free from imperfections.
Disadvantages: Requires special protection against external corrosion in some types of ground. Often subject to growth of incrustations or tuberculations internally unless lined with concrete.
Merits: Economical and resistant to decay under most soil conditions. Light and easy to handle and lay.
Disadvantages: Vulnerable to damage during handling.
UPVC (unplasticised polyvinyl chloride) and MDPE (medium density polyethylene)
Merits: Light and flexible, easy to handle and install. Low cost compared with metal pipes.
Disadvantages: Deformation and stretching due to stress over a period of time. Susceptible to aromatic hydrocarbons (e.g. petrol) penetrating the pipe wall and contaminating the water supply.
Merits: Sometimes economic in large sizes.
Disadvantages: Heavy and somewhat inflexible in use. Cannot be cut on site and joints allow only limited angular deflection.
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