This standard specifies the material, dimensions, hardness, and other requirements for circular high-strength structural steel washers. These hardened washers are intended for use with high-strength structural bolts (e.g., Grade 8.8, 10.9) to ensure proper tensioning and distribute the clamping load.
Specifies requirements for plain washers for high strength structural bolting.
Quick Reference Values
Required Hardness Range35 to 45 HRC
Nominal Thickness for M20 Washer4.0 mm
Inside Diameter for M20 Washer22.0 mm
Outside Diameter for M20 Washer42.0 mm
Applicable Bolt Property Classes8.8 and 10.9
Practical Notes
These hardened washers are essential to prevent 'cupping' and loss of preload when tightening high-strength bolts; do not substitute with mild steel washers.
Hardness is the most critical property. It should be verified upon material receipt to ensure it is within the 35-45 HRC range.
Ensure washers are placed under the element being turned (usually the nut) to distribute pressure and prevent galling.