IS 458 specifies the manufacturing, dimensional, and testing requirements for precast concrete pipes (both reinforced and unreinforced). It is widely used by civil and infrastructure engineers to select appropriate pipe classes (like NP2, NP3, and NP4) for sewerage, drainage, highway culverts, and water mains based on traffic loads and burial depths.
Specifies requirements for spun precast concrete pipes, with or without reinforcement, used for water and sewage conveyance.
Quick Reference Values
Minimum concrete grade for unreinforced pipes (NP1)M25
Minimum concrete grade for reinforced pipesM35
Minimum clear cover to reinforcement15 mm
Hydrostatic test pressure for Non-Pressure (NP) pipes0.07 MPa (approx 7m head)
Tolerance on length of pipe±1 percent or ±10 mm (whichever is greater)
Tolerance on internal diameter (up to 300 mm)±3 mm
Practical Notes
Pipe classification alone does not guarantee structural integrity; engineers must specify proper bedding (like First Class or Concrete Cradle) based on trench depth and traffic loads.
NP3 pipes are the most common choice for highway cross-drainage and sewers under vehicular traffic, while NP2 is typically restricted to light traffic or pedestrian zones.
Testing methods for these pipes, such as the three-edge bearing test and hydrostatic test, are not detailed here but in the companion code IS 3597.