USS Flat Washers

USS flat washers, or United States Standard washers, were designed to meet engineering requirements for the majority of industrial applications for manufacturing and maintenance and repair (MRO). The outside diameters, inside diameters, and thickness specifications were developed to meet the largest range of applications. Standard USS flat washers are made from low carbon steel whereas USS through-hardened flat washers are made from a higher grade steel (SAE 1035 – 1050 steel) and heat-treated. They perform the same function as USS plain washers, but for use specifically with high-strength hardened steel bolts. Product standards require all through-hardened washers 1/4” diameter and larger to bear the insignia identifying its manufacturer.

USS Flat Washer Resources