Washers

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Expected delivery: Wed, Nov 18

Washers spread the load under a bolt head or nut, protect the surface, and in some cases help keep a joint tight or sealed. This section covers SAE and USS flat washers, hardened flat washers, fender washers, split lock washers, internal and external tooth lock washers, bonded sealing washers with a rubber backing, and nylon washers. Materials include zinc-plated and plain steel, hardened steel, galvanized steel, stainless steel and nylon.

What to check before you order

  • SAE or USS pattern. SAE flat washers have a smaller outside diameter and a closer fit on the bolt. USS washers are larger and thicker, a common choice for wood and construction work.
  • Hardness. High-strength bolts such as Grade 8 should use hardened flat washers so the washer does not dish under load.
  • Fender washers. Their large outside diameter spreads load on thin sheet metal, plastic and slotted holes.
  • Sealing. Bonded sealing washers are used on roofing and siding screws and on fittings where water or fluid must be kept out.
  • Material match. Use stainless washers with stainless bolts to avoid corrosion between metals.

Shop matching nuts and hex bolts and cap screws, or see all fasteners.

Common questions

What size washer do I need for a 1/2 in. bolt?

Washers are sold by the nominal bolt size they fit, so a 1/2 in. bolt takes a 1/2 in. washer, which has a slightly larger hole than the bolt. The SAE or USS pattern then sets the outside diameter and thickness.

Where does a split lock washer go?

Place a split lock washer directly under the nut or screw head that is being turned. If a flat washer is also used, the flat washer sits against the part and the lock washer goes between it and the nut or head.

Washers: page 8

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