What is the primary purpose of hardened structural washers?

To distribute the high clamping force of structural bolts over a larger area and prevent embedding into softer structural steel members.

Which Indian Standards are typically used alongside this specification?

IS 3757 for high strength bolts, IS 6623 for high strength nuts, and IS 4000 for the code of practice in steel structures.

Can hardened washers be reused?

Washers should generally not be reused in fully tensioned, slip-critical connections once they have been heavily torqued and deformed.

IS 3063

: 1994

Washers for high strength structural bolting

CurrentFrequently UsedSpecificationStructural Engineering · Fasteners, Bolts and Anchors

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This specification outlines the requirements for washers used in high strength structural bolting assemblies. It covers dimensions, material composition, hardness properties, and surface finish to ensure reliable clamping forces and safe load distribution in friction-grip connections.

Covers requirements for steel washers for use in high strength structural bolting.

Quick Reference Values

Hardness Range35 to 45 HRC (Typical for hardened washers)

Hole ToleranceMedium (H13/H14)

Nominal Size RangeStandard sizes matching M12 to M36 bolts

Practical Notes

Always place the washer with the chamfered edge facing the bolt head to prevent interference with the under-head fillet radius.

Ensure the washer hardness is appropriate to prevent galling or embedding into softer structural steel under high bolt tension.

Ensure the protective coating (e.g., hot-dip galvanizing) on washers matches the bolts and nuts to prevent galvanic corrosion.