316L vs 304L Stainless Steel
304L and 316L are two of the most common stainless steel grades used for washers, spacers, and fasteners. Both resist rust better than plain steel. The practical difference for most buyers is corrosion resistance, especially around chlorides (salt).
304L stainless
304L is a widely used “general purpose” stainless. It works well for many indoor and mild outdoor jobs where the part is not constantly exposed to salt water, road salt, or harsh chemicals.
316L stainless
316L includes molybdenum, which improves resistance to pitting and crevice corrosion in chloride environments. That is why 316L is often chosen for marine, coastal, outdoor, and chemical-exposure applications. A large share of the EXTSW catalog is 316L for that reason.
What the "L" means: 304L and 316L
The "L" stands for low carbon. 304L and 316L are limited to a maximum of 0.03% carbon, while standard 304 and 316 can contain up to 0.08% carbon. Lower carbon helps the steel keep its corrosion resistance after welding or heat exposure, because less carbon is available to tie up the chromium that protects the surface. All EXTSW washers and spacers are made from L-grade stainless.
A warning about imported "stainless" washers and spacers
Every EXTSW part is machined in the USA from certified, US-made 304L or 316L stainless, with the alloy stated on every listing. Many imported washers just say “stainless steel” with no alloy grade, and some lower-cost stainless grades rust much faster than 304L or 316L. Know what you’re buying.
Which should you buy?
- Choose 316L when the washer or spacer will see salt air, salt water, de-icing salt, or corrosive chemicals, or when you simply want the more corrosion-resistant option.
- Choose 304L when the environment is milder and you want a common, capable stainless grade.
About our material
EXTSW thick stainless washers and spacers are made in the USA from US-foundry certified material. Each product page lists the grade (304L, 316L, or others when offered) along with the actual ID, OD, and thickness or length.
Not a substitute for engineering advice
Grade choice depends on your full environment (temperature, chemicals, stress, and codes). If you have a specification calling out a grade, follow that specification. We are happy to help you find a matching size in the grade you need.
Need a size in 316L or 304L?
Browse the ID and OD collections on extsw.com, or call 209-517-3150 / email contact@extsw.com with your dimensions.