Flange Nuts
A flange nut is a hex nut with an integrated, wider washer-like flange at its base. The flange spreads clamp load over a larger area — useful on soft, slotted, or oversized holes — and eliminates the separate washer, speeding assembly. Serrated flange nuts add teeth on the bearing face that bite into the surface to resist loosening under vibration. Eugene Fastener & Supply stocks flange nuts in steel (including the Gibraltar serrated line), 18-8 stainless, and metric, in coarse and fine threads.
Use a smooth flange nut where you don’t want to mar a finished surface, and a serrated flange nut where vibration resistance matters and surface marring is acceptable. For higher-grade serrated flange lock nuts (Grade 5, Grade 8, metric, and stainless), see our flange lock nuts. We sell by the piece or in bulk, cross-reference part numbers, and ship same day on orders placed before 2pm Pacific.
Flange Nuts — Serrated, Smooth, Stainless & Metric
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Flange Nuts by Type & Material
- Steel Flange Nuts — zinc-plated, the general-purpose choice.
- Gibraltar Flange Nuts — serrated flange nuts engineered for strong vibration resistance.
- Stainless Flange Nuts — 18-8 for corrosion resistance.
- Metric Flange Nuts — class 8/10, coarse pitch.
For higher-grade locking versions, see our serrated flange lock nuts (Grade 5, Grade 8, metric, and stainless).
Smooth vs. Serrated — Which Flange Nut?
- Serrated flange nut: teeth bite into the bearing surface to resist back-off under vibration. Best for non-finished surfaces and high-vibration joints. The serrations will mar the surface.
- Smooth flange nut: no teeth — use where you can’t mar the surface or where the part rotates against the flange.
- Match the grade to your bolt; step up to a Grade 8 serrated flange lock nut for high-strength, high-vibration assemblies.
Flange Nut FAQ
What is a flange nut?
A flange nut is a hex nut with a wide, integrated flange at its base that acts like a built-in washer. It spreads clamp load over a larger area and removes the need for a separate washer, which speeds assembly. Serrated versions have teeth on the flange face that resist loosening.
What’s the difference between a serrated and a smooth flange nut?
A serrated flange nut has teeth on the bearing face that bite into the surface to resist vibration loosening — ideal for non-finished surfaces. A smooth flange nut has no teeth and is used where the surface must not be marred or where a part rotates against the flange.
Do flange nuts need a washer?
Usually not — the flange acts as the washer, distributing load. On very soft materials or oversized holes you may still add a washer, but for most assemblies the flange alone is sufficient and faster.
Are serrated flange nuts a type of lock nut?
Yes — the serrations make them prevailing-resistance lock nuts. For higher-strength locking (Grade 5, Grade 8, metric, stainless), use our serrated flange lock nuts. Note serrations mar the bearing surface, so they’re not for finished faces.
What materials and grades are available?
Steel (zinc, including the Gibraltar serrated line), 18-8 stainless, and metric class 8/10, in coarse and fine threads. Match the nut grade to your bolt.
Do you sell by the piece and cross-reference part numbers?
Both by the piece and in bulk. Send any manufacturer or DIN part number and we’ll match it to a stocked equivalent, usually same business day.
Why Buy Flange Nuts from Eugene Fastener
- Serrated and smooth, steel, stainless, and metric — including the Gibraltar serrated line.
- By the piece or in bulk, with cross-reference and grade-matching help.
- Same-day shipping before 2pm Pacific.
- Since 1969 — serving Pacific Northwest industry for over 55 years.
Pair flange nuts with our hex bolts and flange bolts and hex nuts. For more vibration resistance see our lock nuts, or browse all nut types. Contact our sales team for grade matching, cross-references, or bulk pricing. Eugene Fastener & Supply — serving Pacific Northwest manufacturers and contractors since 1969.