Standard Circular F436 Washer
What It Does
The standard circular hardened washer is the most widely used washer for high-strength structural bolting. It installs beneath the turned element of the connection, the nut or the bolt head, giving a hard bearing surface that prevents embedment into the connected steel and distributes the clamping load across the joint. Circular hardened washers are most often used with F3125 Grades A325, A490, and 144 structural bolts in standard holes. These washers meet the ASTM F436 specification.
Standard circular F436 hardened washers are also used with F1554 anchor bolts in Grades 36, 55, and 105. Hardened washers provide a smooth bearing surface against the base plate of light poles, structural steel columns, overhead sign structures, or other steel members bolted to a concrete foundation.
Because a high-strength bolt develops significant clamping force when it is tensioned, the element that turns during tightening can gall or dig into softer connected material without a hardened washer beneath it. The standard circular washer provides the smooth, heat-treated bearing surface that lets the connection reach and hold its specified pretension. It is the default washer for most standard-hole structural connections, which is why it is stocked more widely than any other hardened washer pattern.
When to Use a Standard Circular Washer
A standard circular F436 washer is appropriate when the hole is a standard-size round hole and the bearing surface is flat and perpendicular to the bolt axis. If the hole is oversized or slotted, an extra thick washer is typically specified instead. If the bearing surface is sloped, such as the flange of an American Standard beam, a beveled washer is used. For connections with limited edge clearance, a clipped washer may be required. When none of those conditions apply, the standard circular washer is the correct and most economical choice.
Finishes and Material Types
Standard circular F436 washers are available in plain finish and hot-dip galvanized. Type 1 carbon or alloy steel washers are used for standard structural assemblies, while Type 3 weathering steel washers are used with weathering-steel assemblies and are typically furnished plain. The washer finish and material type should match the bolt and nut used in the assembly.
Standard Circular Washer Dimensions
Dimensions below are per ASTM F436, in inches.
| Nominal Washer Size | I.D. min | I.D. max | O.D. min | O.D. max | Thickness Std min | Thickness Std max | Thickness X-Thick min | Thickness X-Thick max |
|---|---|---|---|---|---|---|---|---|
| 1/4″ | 0.281″ | 0.313″ | 0.593″ | 0.657″ | 0.051″ | 0.08″ | … | … |
| 5/16″ | 0.344″ | 0.376″ | 0.656″ | 0.72″ | 0.051″ | 0.08″ | … | … |
| 3/8″ | 0.406″ | 0.438″ | 0.781″ | 0.845″ | 0.051″ | 0.08″ | … | … |
| 7/16″ | 0.469″ | 0.501″ | 0.89″ | 0.954″ | 0.051″ | 0.08″ | … | … |
| 1/2″ | 0.531″ | 0.563″ | 1.031″ | 1.095″ | 0.097″ | 0.177″ | 0.305″ | 0.375″ |
| 9/16″ | 0.625″ | 0.657″ | 1.156″ | 1.22″ | 0.11″ | 0.177″ | 0.305″ | 0.375″ |
| 5/8″ | 0.688″ | 0.72″ | 1.281″ | 1.345″ | 0.122″ | 0.177″ | 0.305″ | 0.375″ |
| 3/4″ | 0.813″ | 0.845″ | 1.436″ | 1.5″ | 0.122″ | 0.177″ | 0.305″ | 0.375″ |
| 7/8″ | 0.938″ | 0.97″ | 1.718″ | 1.782″ | 0.136″ | 0.177″ | 0.305″ | 0.375″ |
| 1″ | 1.063″ | 1.126″ | 1.937″ | 2.063″ | 0.136″ | 0.177″ | 0.305″ | 0.375″ |
| 1-1/8″ | 1.188″ | 1.251″ | 2.187″ | 2.313″ | 0.136″ | 0.177″ | 0.305″ | 0.375″ |
| 1-1/4″ | 1.375″ | 1.438″ | 2.437″ | 2.563″ | 0.136″ | 0.177″ | 0.305″ | 0.375″ |
| 1-3/8″ | 1.5″ | 1.563″ | 2.687″ | 2.813″ | 0.136″ | 0.177″ | 0.305″ | 0.375″ |
| 1-1/2″ | 1.625″ | 1.688″ | 2.937″ | 3.063″ | 0.136″ | 0.177″ | 0.305″ | 0.375″ |
| 1-3/4″ | 1.875″ | 1.938″ | 3.312″ | 3.438″ | 0.178″ ᴮ | 0.28″ ᴮ | 0.305″ | 0.375″ |
| 2″ | 2.125″ | 2.188″ | 3.687″ | 3.813″ | 0.178″ ᴮ | 0.28″ ᴮ | 0.305″ | 0.375″ |
| 2-1/4″ | 2.375″ | 2.438″ | 3.937″ | 4.063″ | 0.24″ ᶜ | 0.34″ ᶜ | 0.305″ | 0.375″ |
| 2-1/2″ | 2.625″ | 2.688″ | 4.437″ | 4.563″ | 0.24″ ᶜ | 0.34″ ᶜ | 0.313″ | 0.375″ |
| 2-3/4″ | 2.875″ | 2.938″ | 4.937″ | 5.063″ | 0.24″ ᶜ | 0.34″ ᶜ | 0.313″ | 0.375″ |
| 3″ | 3.125″ | 3.188″ | 5.437″ | 5.563″ | 0.24″ ᶜ | 0.34″ ᶜ | 0.313″ | 0.375″ |
| 3-1/4″ | 3.375″ | 3.5″ | 5.875″ | 6.125″ | 0.24″ ᶜ | 0.34″ ᶜ | 0.313″ | 0.375″ |
| 3-1/2″ | 3.625″ | 3.75″ | 6.375″ | 6.625″ | 0.24″ ᶜ | 0.34″ ᶜ | 0.313″ | 0.375″ |
| 3-3/4″ | 3.875″ | 4″ | 6.875″ | 7.125″ | 0.24″ ᶜ | 0.34″ ᶜ | 0.313″ | 0.375″ |
| 4″ | 4.125″ | 4.25″ | 7.375″ | 7.625″ | 0.24″ ᶜ | 0.34″ ᶜ | 0.313″ | 0.375″ |
| Footnotes: A — Clipped edge E shall be not closer than 7/8 of the bolt diameter from the center of the washer. B — 9/16 in. nominal. C — 1/4 in. nominal. D — Nominal washer sizes are intended for use with fasteners of the same nominal thread size. | ||||||||
Availability
Stocked in plain finish and hot-dip galvanized in common diameters. Larger and special sizes manufactured to order.