Stainless Steel Flat Washers
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What are stainless steel flat washers? Stainless steel flat washers are round, flat washers that distribute a fastener's load over a wider area and protect the surface from damage, the most common washer type. Made from 18-8, 304, and 316 stainless, plus A2 and A4 metric, they resist rust in wet, coastal, and outdoor use.
Stainless Steel Flat washers
Standard Flat Washers
Corrosion-resistant general-purpose round washers in 18-8, 304, 316, and metric A2/A4 stainless that spread load and protect the surface.
NAS (National Aerospace Standard) Flat Washers
Precision flat washers built to National Aerospace Standard tolerances for aircraft and high-reliability assemblies.
800 Series MS (Military Standard) Flat Washers
Flat washers manufactured to 800-series Military Standard specifications for defense and aerospace applications.
900 Series AN (Air Force, Navy) Flat Washers
Flat washers built to AN (Army-Navy) specifications for aircraft and military fastening.
USS vs SAE and how to pick a size
Flat washers come in two common patterns. USS washers have a larger outer diameter and thicker body to spread load over a wide area, suited to construction and larger fasteners, while SAE washers have a smaller outer diameter and tighter fit for automotive, machinery, and Grade 5 or Grade 8 bolts. Match the inner diameter to the bolt and pick the pattern for how much bearing area you need, then choose the grade for the environment, with 316 or A4 for coastal exposure.
Why choose stainless steel flat washers
- Load spreading: distributes force to protect the surface.
- Corrosion resistance: holds up in wet and outdoor use.
- Grade range: 18-8, 304, 316, and metric A2/A4.
- Patterns: USS wide and SAE tight for the right fit.
Common applications for stainless flat washers
- Under bolt heads and nuts to spread load
- Construction and larger fasteners (USS)
- Automotive and machinery (SAE)
- Marine and coastal hardware (316 or A4)
For thin or soft material needing a wider footprint, see stainless fender washers, and browse every pattern and finish on the main flat washers category.
Stainless Steel Flat Washers FAQ
What is the difference between USS and SAE washers?
USS washers have a larger, thicker footprint for construction and bigger fasteners. SAE washers are smaller and tighter for automotive, machinery, and graded bolts.
What grades do your flat washers come in?
Inch in 18-8, 304, and 316, and metric in A2 and A4. A2 is comparable to 304 and A4 to 316.
Which grade for coastal use?
Use 316 or metric A4 for coastal and saltwater exposure, since they resist pitting better than 18-8, 304, or A2.