What are the standard classes of zinc coating in IS 277:1992?

Heavy (275 g/m²), Medium (200 g/m²), and Light (120 g/m²), as per Table 2.

What are the base metal grades available for the steel sheets?

Ordinary (O), Drawing (D), Deep Drawing (DD), and Extra Deep Drawing (EDD) as specified in Clause 5 and Table 1.

What are the standard dimensions of a corrugated sheet?

Standard widths are 800mm, 1000mm, and 1200mm, with a corrugation pitch of 75mm and depth of 17.5mm (Clause 10.3).

How is the zinc coating mass verified?

By the stripping test method described in IS 6745, which involves weighing a sample before and after chemically removing the zinc coating.

IS 2779

: 1991

Galvanized steel sheets (plain and corrugated)

CurrentFrequently UsedSpecificationBIMMaterials Science · Roofing Materials

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This standard (commonly known as IS 277; the number IS 2779 is a likely typo) specifies the requirements for plain and corrugated galvanized steel sheets. It covers various material grades, zinc coating mass classes, dimensions, tolerances, and testing procedures for sheets primarily used in roofing, cladding, and paneling.

Specifies requirements for hot-dip galvanized plain and corrugated steel sheets.

Quick Reference Values

Minimum total zinc coating (both sides) for heavy coating class275 g/m²

Minimum total zinc coating (both sides) for medium coating class200 g/m²

Minimum total zinc coating (both sides) for light coating class120 g/m²

Standard pitch of corrugations75 mm

Standard depth of corrugations17.5 mm

Number of corrugations for 800 mm wide sheet11

Maximum Sulphur content for Ordinary (O) grade base metal0.050 percent

Practical Notes

The zinc coating mass (e.g., 275 g/m²) is the most critical parameter for durability and corrosion resistance; always specify this when ordering.

Ensure the 'bend test' is passed for the specified grade, especially for sheets that require forming or bending on site, to avoid cracking of the zinc coating.

This 1992 version is superseded by IS 277:2018, which includes additional grades and coating options. Always refer to the latest version for new projects.