ASME/ANSI B 18.21.1 (SAE) Flat Washer
ASME/ANSI B18.21.1 (SAE) Flat Washers are precision-formed flat washers designed to provide a supporting surface between a fastener and the connected component. Their simple flat profile helps distribute the clamping force over a wider area, reducing concentrated pressure around the bolt hole and helping protect the surface of the assembled material. The washer also provides a consistent bearing interface between the fastener head or nut and the workpiece.
The SAE washer design is characterized by its relatively small outside diameter compared with larger-pattern flat washers, making it suitable where a compact bearing surface is preferred without significantly increasing the footprint of the fastening point. The inside diameter is matched to the nominal fastener size, while the outside diameter and thickness determine how the clamping load is transferred to the surrounding material. This makes dimensional compatibility important when selecting a washer for a particular bolt, screw, or nut.
Specification:
ASME/ANSI B18.21.1 (SAE) Flat Washers are manufactured according to the SAE series dimensional requirements for flat washers used with inch-series fasteners. The specification defines the washer geometry and dimensional relationship between the inside diameter, outside diameter, and thickness, allowing the washer to provide a consistent bearing surface under the head of a bolt, screw, or nut. The washers can be supplied in carbon steel, alloy steel, or stainless steel, depending on the mechanical and environmental requirements of the assembly. Carbon steel is suitable for general-purpose fastening, while stainless steel such as 304 and 316 can be selected for applications where improved corrosion resistance is required. Available finishes may include plain, zinc plated, hot-dip galvanized, black oxide, or other specified coatings. Material, finish, and dimensional requirements can be selected according to the applicable standard and customer requirements.
| Item | Specification |
|---|---|
| Standard | ASME/ANSI B18.21.1 |
| Washer Type | SAE Flat Washer |
| Shape | Flat Round Washer |
| Material | Carbon Steel/Stainless Steel |
| Inner Diameter: | Φ#2-Φ3” |
| Surface Treatment | Plain,Zinc Plated,Black Oxidation,Bright Finish,Passivation |
| Compatibal Fasteners | Bolts/Screws/Studs/Nuts |
Dimension Chart of ASME/ANSI B 18.21.1 (SAE) Stainless Steel Flat Washer :
The dimension chart of ASME/ANSI B18.21.1 (SAE) Stainless Steel Flat Washers provides detailed specifications including inside diameter, outside diameter, thickness, and washer size according to SAE flat washer requirements. These standardized dimensions ensure proper fit and compatibility with corresponding bolts, screws, and nuts, helping distribute clamping loads evenly and protect fastening surfaces from damage. The SAE series typically features a larger outside diameter compared with standard flat washers, making it suitable for applications requiring improved load distribution and surface coverage.
| Mon | #2 | #4 | #6 | #8 | 3/16 | #10 | #12 | 1/4 | 5/16 | 3/8 | 7/16 | 1/2 | 9/16 | 5/8 | 3/4 | 7/8 | 1 | 1-1/8 | 1-1/4 | 1-3/8 | 1-1/2 |
| d max | 0.094 | 0.133 | 0.164 | 0.196 | 0.265 | 0.227 | 0.265 | 0.296 | 0.359 | 0.421 | 0.484 | 0.546 | 0.609 | 0.686 | 0.842 | 0.968 | 1.092 | 1.28 | 1.405 | 1.53 | 1.655 |
| d min | 0.089 | 0.12 | 0.151 | 0.183 | 0.245 | 0.214 | 0.245 | 0.276 | 0.339 | 0.401 | 0.464 | 0.526 | 0.589 | 0.649 | 0.805 | 0.931 | 1.055 | 1.243 | 1.368 | 1.493 | 1.618 |
| dc max | 0.25 | 0.32 | 0.39 | 0.453 | 0.577 | 0.515 | 0.577 | 0.64 | 0.703 | 0.827 | 0.937 | 1.092 | 1.186 | 1.342 | 1.499 | 1.78 | 2.03 | 2.28 | 2.53 | 2.78 | 3.03 |
| dc min | 0.245 | 0.307 | 0.37 | 0.433 | 0.557 | 0.495 | 0.557 | 0.62 | 0.683 | 0.807 | 0.917 | 1.055 | 1.149 | 1.305 | 1.462 | 1.743 | 1.993 | 2.243 | 2.493 | 2.743 | 2.993 |
| h max | 0.025 | 0.04 | 0.065 | 0.065 | 0.065 | 0.065 | 0.08 | 0.08 | 0.08 | 0.08 | 0.08 | 0.121 | 0.121 | 0.121 | 0.16 | 0.16 | 0.16 | 0.16 | 0.192 | 0.192 | 0.192 |
| h min | 0.016 | 0.025 | 0.036 | 0.036 | 0.036 | 0.036 | 0.051 | 0.051 | 0.051 | 0.051 | 0.051 | 0.074 | 0.074 | 0.074 | 0.108 | 0.108 | 0.108 | 0.108 | 0.136 | 0.136 | 0.136 |
- RELATED WASHER LISTS:
- DIN125 Flat Washer
- DIN127 Spring Lock Washer
- F436 Hardened Steel Washers
- DIN9021 Large Washer
- ASME/ANSI B 18.21.1 (USS) Flat Washer
- ASME/ANSI B18.21.1 Helical Spring-Lock Washer
- DIN25201 Stainless Steel Double Fold Self-locking Washer
- DIN6797A Stainless Steel External Teeth Lock Washers
- Stainless Steel DIN6797J Internal Teeth Lock Washers
Application of ASME/ANSI B 18.21.1 (SAE) Flat Washer :
Load Distribution Under Fastener Heads and Nuts
SAE Flat Washers are commonly used where the clamping force from a bolt head or nut needs to be distributed over a broader area. They can be used on steel brackets, mounting plates, machine panels, fabricated frames, and bolted joints to reduce concentrated bearing pressure around the fastening hole.
Protection of Finished and Softer Surfaces
A flat washer can help separate the rotating fastener from the surface of the connected component during tightening. This makes SAE washers useful for painted metal panels, coated components, aluminum parts, finished brackets, and assembled surfaces where direct contact with the bolt head or nut could damage the finish.
Thin Sheet and Fabricated Components
The compact SAE outside diameter makes this washer pattern suitable where the fastening point does not have a large amount of available surface area. Applications can include sheet-metal brackets, instrument panels, equipment covers, mounting rails, metal enclosures, and fabricated assemblies.