IS 8329 is India's primary specification for ductile iron (DI) pressure pipes — the backbone of urban water supply systems. DI pipes combine the strength of steel with the corrosion resistance of cast iron. Classes K7/K9/K12 handle pressures from 10-50 bar depending on diameter.
Specification for centrifugally cast ductile iron pipes for pressure applications (water, sewerage, gas) covering grades, dimensions, mechanical properties, coatings, and testing.
Key Values
Tensile strength min420 MPa
Elongation min10%
Standard pipe length5.5m or 6.0m
Practical Notes
! K9 is the standard class for most municipal water supply projects in India.
! Always use IS 5382 rubber rings for push-fit (Tyton) joints — do not substitute non-IS rings.
! Internal cement lining protects against tuberculation and red water — do not use unlined DI pipes for potable water.
! External zinc + bitumen coating provides corrosion protection for 50+ years in normal soils.
! DI pipe is significantly more expensive than HDPE but offers higher pressure rating and longer life.