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IS 5372:1990 is the Indian Standard (BIS) for taper washers for channels. This standard provides specifications for the material, dimensions, and other requirements for steel taper washers. These washers are specifically designed for use with Indian Standard channel sections (ISMC) to provide a flat, parallel bearing surface for bolt heads and nuts on their sloped flanges.
Specifies dimensions and other requirements for taper washers for use with channels.
Overview
Status
Current
Usage level
Specialized
Domain
Structural Engineering — Fasteners, Bolts and Anchors
Consolidated list per BIS. For the text of each amendment, refer to the BIS portal link above.
steelfastenerswashers
International Equivalents
Similar International Standards
ASTM F436M-19ASTM International, USA
HighCurrent
Standard Specification for Hardened Steel Washers (Metric)
Covers beveled (tapered) hardened steel washers with a 1:6 slope for structural applications.
DIN 434:1992-06Deutsches Institut für Normung, Germany
MediumCurrent
Square Taper Washers For U-Sections
Specifies square taper washers specifically for use with U-profile channels, but with a different taper.
JIS B 1256:2008Japanese Industrial Standards Committee, Japan
LowCurrent
Plain washers
Includes a category for tapered square washers, but with different standard taper options (5% or 8%).
BS 3410:1961British Standards Institution, UK
MediumWithdrawn
Specification for metal washers for general engineering purposes
Included Type C (Square Taper Washers for Channels and Beams) with a 1 in 6 taper.
Key Differences
≠The specified taper angle in IS 5372 is a mean slope of 1:6 (approx. 9.5°), which matches ASTM F436. This differs significantly from DIN 434 which specifies an 8% taper (approx. 4.5°).
≠IS 5372 specifies mild steel (e.g., IS 2062) which is relatively soft and unhardened. In contrast, ASTM F436 mandates through-hardened steel with a specified Rockwell hardness (38-45 HRC), making it suitable for high-strength bolting applications.
≠IS 5372 is intended for general purpose structural steelwork, whereas ASTM F436 washers are a required component of high-strength structural bolting assemblies (e.g., with ASTM A325/A490 bolts).
Key Similarities
≈The primary function across all standards is to provide a flat, parallel bearing surface for a nut or bolt head when clamping onto a sloped surface, such as a channel flange.
≈The basic geometry is consistent: a square-shaped washer with a central hole and one face machined at a specific taper.
≈All standards designate the washer size based on the nominal diameter of the bolt it is designed to be used with (e.g., M12, M16, M20).
Parameter Comparison
Parameter
IS Value
International
Source
Taper Angle
1:6 (mean slope)
1:6
ASTM F436M-19
Taper Angle
1:6 (approx. 9.5°)
8% (approx. 4.5°)
DIN 434:1992-06
Material Specification
Mild Steel, e.g., IS 2062
Steel, through-hardened
ASTM F436M-19
Hardness Requirement
Not specified (implied soft)
38 to 45 HRC
ASTM F436M-19
Hole Diameter (for M20 bolt)
22.0 mm
22.0 mm
ASTM F436M-19
Side Length (for M20 bolt)
44.0 mm
44.0 mm
DIN 434:1992-06
Nominal Thickness (for M20 bolt)
6.0 mm (at mid-width)
5.6 mm
DIN 434:1992-06
⚠ Verify details from original standards before use
Key Values4
Quick Reference Values
Taper slope1:6
Applicable bolt sizes10 mm to 36 mm
Material specificationSteel conforming to IS 2062
Hardness requirementMinimum 100 HV
Tables & Referenced Sections
Key Tables
Table 1: Dimensions for Taper Washers for Channels