What is the difference between Class 1 and Class 2 valves in IS 778?

Class 1 valves are designed for a safe working pressure of 1.0 MPa, while Class 2 valves are designed for 1.5 MPa.

What are the required hydrostatic test pressures?

For Class 1, the body is tested at 1.5 MPa and the seat at 1.0 MPa. For Class 2, the body is tested at 2.4 MPa and the seat at 1.5 MPa (Table 8).

What nominal sizes are covered by this standard?

The standard covers nominal bore sizes ranging from 8 mm up to 100 mm.

What is the primary material used for the valve body?

Leaded tin bronze (commonly known as gunmetal) conforming to IS 318.

IS 778

: 1984

Copper Alloy Gate, Globe and Check Valves for Waterworks Purposes - Specification

CurrentFrequently UsedSpecificationBIMMEP · Plumbing Fixtures and Valves

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IS 778 covers the material, dimensional, and testing specifications for copper alloy (gunmetal/brass) gate, globe, and check valves used in water supply and plumbing networks. Engineers use this code to specify valve classes based on working pressure and to ensure dimensional standardisation for both threaded and flanged connections.

Specifies requirements for copper alloy gate, globe, and check valves for general waterworks purposes.

Quick Reference Values

size range8 mm to 100 mm

class 1 working pressure1.0 MPa

class 2 working pressure1.5 MPa

class 1 body test pressure1.5 MPa

class 1 seat test pressure1.0 MPa

class 2 body test pressure2.4 MPa

class 2 seat test pressure1.5 MPa

minimum test duration2 minutes

Practical Notes

Always specify whether the required valve ends are screwed or flanged, as the code dictates different face-to-face dimensions for both.

For aggressive or hard water areas, ensure the spindle material is specified as dezincification-resistant (DZR) brass.

Do not use these specifications for valves exceeding 100 mm nominal bore; larger sizes typically transition to cast iron valves (IS 780 or IS 14846).