Components, systems and materials › Water and drainage components › Ductile iron pipe
Ductile iron pipe
What it is
A ductile iron pipe is a cast iron pipe in which graphite forms spheres, making the metal strong, tough and able to bend slightly without cracking.
Where it is used
Water transmission and distribution mains, pumping mains and sometimes sewers and fire mains.
How it works
The spheroidal graphite structure gives ductility, so the pipe resists ground movement, traffic loads and pressure surges far better than old grey cast iron. Joints are usually push-on socket and spigot with rubber gaskets, which allow slight deflection and are quick to assemble.
Types
- Pressure classes such as K7 and K9
- push-on and mechanical joints
- restrained joints for thrust areas
- flanged pipes for pump houses
Materials
Ductile iron with internal cement mortar lining and external zinc coating with bitumen; rubber gaskets.
Class is selected from internal pressure, surge and external load. Thrust blocks or restrained joints are provided at bends and tees. Polyethylene sleeving may be used in corrosive soils.
Installation and QA steps
- Inspect pipes and linings on delivery.
- Bed pipes on prepared trench.
- Joint with lubricated gasket.
- Provide thrust restraint.
- Hydro-test sections.
- Disinfect before use.
- Corrosion in aggressive soils without protection
- joint leaks from poor assembly
- damaged lining
- thrust failure at bends
Codes cited
- IS 8329 (India): Centrifugally cast ductile iron pressure pipes for water, gas and sewage.
Cited by number only. We do not reproduce code text, tables or figures.
Related
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