Washer, USS Flat

USS Flat Washers are the most common washers and are offered with Zinc plating, Yellow Zinc plating, Stainless Steel, Type 316 Stainless Steel and Hot Dipped Galvanized finishes, in a variety of sizes.  Washers are sized by the fastener they fit. For example, a 1/4″ washer fits a 1/4″ bolt.

Type 316 Stainless Steel

Hot Dipped Galvanized

“USS” on flat washers stands for United States Standard, indicating a washer pattern with a larger outer diameter and thicker body than SAE washers, originally tied to coarse‑threaded USS bolts.

What USS Flat Washers Are

• USS (United States Standard / Unified Standard Series) washers were among the earliest commercial washer standards in the U.S.
• They have larger OD and thicker bodies than SAE washers for the same bolt size, providing a wider bearing surface.
• Designed originally for coarse-threaded USS bolts, they are widely used in construction, structural steel, heavy equipment, and industrial applications.

In shed construction, flat washers are placed between bolt heads or nuts and the wood, metal, or other surfaces to spread the load, protect the material, and ensure a stable, durable connection