What is the standard hydrostatic test pressure for these fittings?

Fittings up to 600 mm in diameter are tested at 2.5 MPa, while larger sizes are tested at 1.5 MPa.

What types of joints are covered by this standard?

The standard covers flanged joints and socket-and-spigot joints used in pressure pipelines.

Can cast iron fittings be used with modern ductile iron pipes?

While they might fit dimensionally, it is generally recommended to use Ductile Iron fittings with DI pipes to maintain consistent pressure ratings and ductility.

IS 781

: 1986

Cast iron fittings for pressure pipes for water, gas and sewage - Specification

CurrentSpecializedSpecificationBIMWater Resources · Water Supply and Plumbing

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This specification covers the requirements for cast iron fittings used with pressure pipes in water supply, gas transmission, and sewage systems. It defines dimensions, tolerances, mechanical properties, and hydrostatic testing parameters to ensure reliable fluid transport.

Specifies requirements for cast iron fittings suitable for use with pressure pipes conveying water, gas, or sewage.

Quick Reference Values

Minimum Tensile Strength150 MPa

Maximum Brinell Hardness210 HB

Hydrostatic Test Pressure (<= 600 mm)2.5 MPa

Hydrostatic Test Pressure (> 600 mm)1.5 MPa

Practical Notes

Cast iron is brittle; handle fittings with care to avoid impact damage during transport and laying.

Ensure proper selection of gaskets and uniform bolting for flanged fittings to prevent leaks or cracking the flange.

Ductile iron (DI) fittings (IS 9523) have largely replaced CI fittings in modern projects due to higher strength and durability.