What are the primary applications of pitch-impregnated fibre pipes?

They are used for underground, non-pressure applications such as building drainage, land drainage, and sewerage (Clause 1.1).

What is the key strength requirement for these pipes?

The dry crushing strength, which ensures the pipe can withstand soil and traffic loads when buried. The minimum value varies with pipe diameter (Table 3).

Are these pipes resistant to common chemicals found in sewage?

Yes, the standard includes tests for resistance to dilute sulphuric acid, sodium carbonate, and sodium sulphate to ensure durability in typical drainage environments (Clause 7).

How is jointing performed between two pipes?

Joints are made using separate couplings of the same material. The ends of the pipes and the inside of the couplings are tapered to form a drive-tight joint (Clause 5.1).

IS 11925

: 1986

pitch-impregnated fibre pipes and fittings for drainage purposes

CurrentSpecializedSpecificationWater Resources · Public Health Engineering

Download PDF BIS Portal Google

This standard specifies the requirements for materials, dimensions, manufacture, and performance tests for pitch-impregnated fibre pipes and associated fittings. These components are intended for use in underground non-pressure drainage, sewerage systems, and as conduits for cables.

pitch-impregnated fibre pipes and fittings for drainage purposes

Quick Reference Values

Minimum dry crushing strength (100 mm pipe)2.0 kN/m

Minimum wet crushing strength (100 mm pipe)1.0 kN/m

Maximum water absorption (48h immersion)2.0 percent by mass

Heat resistance test temperature80 ± 2 °C

Boiling water resistanceNo evidence of disintegration after 6 hours

Kerosene resistanceNo delamination or disintegration after 24 hours

Practical Notes

These pipes are lightweight and easy to handle but can be brittle and require careful bedding and backfilling to prevent crushing.

This material technology is largely superseded by modern plastics like PVC and HDPE, which offer better durability, chemical resistance, and jointing integrity.

Joints are typically made with taper-fit couplings, requiring proper alignment and force to ensure a tight seal.