Flange Nuts

Flange nuts combine a hex nut with an integrated washer-like flange at the base. The flange spreads clamp load over a wider area — eliminating a separate washer — and serrated versions bite into the surface to resist loosening. They speed assembly and improve joint reliability. We stock flange nuts in serrated and smooth across grades and materials.

Serrated vs. Smooth

Serrated flange: ribs on the underside grip the bearing surface for anti-loosening performance like a lock washer — the common choice for vibration-prone joints. Smooth flange: a clean bearing face for surfaces that must not be marred, or for softer materials. Serrated flange nuts should not be used where the joint is frequently disassembled or the surface must stay unmarked.

Why Flange Nuts

By building the washer into the nut, flange nuts cut part count and assembly time and guarantee even bearing. The wide flange also distributes load on slotted or oversized holes better than a plain hex nut with no washer.

Materials and Finishes

Grade 5 and Grade 8 steel with zinc plating, and 18-8 / 316 stainless for corrosion resistance. Metric flange nuts use classes 8 and 10. Match to the bolt grade and environment.

Dimensional Standards

Metric hex flange nuts follow DIN 6923 / ISO 4161; inch versions follow IFI flange nut standards.

Selecting the Right Flange Nut

Choose serrated for vibration resistance, smooth where surfaces must not be marred. Match grade to the bolt, material to the environment, and verify thread pitch. Pair serrated flange nuts with a compatible bearing surface — they grip best on bare metal, less on coated or soft surfaces.

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