What materials are specified for bib taps?

Cast brass (conforming to IS 1264 or Grade LCB 2 of IS 292) or gunmetal (conforming to Grade LTB 2 of IS 318) as per Clause 4.

What is the required hydrostatic test pressure for the tap body?

The tap body must withstand a hydrostatic pressure of 2.5 MPa for 2 minutes without leakage, as per Table 5.

What is the minimum flow rate for a 15 mm bib tap?

0.20 litres per second when tested at a constant head of 0.05 MPa, according to Table 6.

What information must be marked on the tap?

The manufacturer's name or trademark, the nominal size (e.g., 15 mm), and the ISI Certification Mark, as per Clause 10.

IS 8931

: 2013

Bib taps and stop taps for water services (cast brass, gunmetal) - Specification

CurrentFrequently UsedSpecificationBIMMEP · Water Supply and Plumbing

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This standard specifies the requirements for materials, dimensions, construction, performance, and testing of cast brass and gunmetal bib taps and stop taps. It is applicable for water services with a maximum working pressure of 1.0 MPa.

Specifies requirements for bib taps and stop taps made of cast brass or gunmetal for domestic water services.

Quick Reference Values

Maximum working pressure1.0 MPa

Hydrostatic test pressure (body)2.5 MPa for 2 min

Hydrostatic test pressure (seat)1.6 MPa for 2 min

Minimum flow rate for 15mm bib tap0.20 L/s at 0.05 MPa head

Minimum thickness of Chromium plating (Type A)0.3 µm

Minimum thickness of Nickel plating (Type A)10 µm

Practical Notes

Always look for the ISI mark on the tap body, which ensures it has been manufactured and tested in compliance with this standard.

The standard specifies flow rates at a very low pressure (0.05 MPa, approx. 5m head); actual flow will be higher in most pressurized systems.

Ensure that the tap's material (brass or gunmetal) is suitable for the local water quality to prevent dezincification or corrosion.