Flange Nut

Flange Nut — Integrated Washer Face Nut | DIN 6923 / DIN 6927 | Serrated & Plain Flange

Flange nuts feature a built-in circular flange at the base that acts as an integrated washer, distributing clamping load over a larger surface area and eliminating the need for a separate flat washer. Manufactured to DIN 6923 (plain flange) and DIN 6927 (serrated flange) standards, our flange nuts are available in M5 to M30 sizes in carbon steel and stainless steel. The serrated underside variant provides additional anti-loosening protection by biting into the mating surface, making flange nuts ideal for automotive, machinery, and steel structure applications where speed of assembly and vibration resistance are priorities.

Material & Specifications

Size Range	M5 to M30 / 3/16″ to 1-1/4″
Standard	DIN 6923 (plain flange), DIN 6927 (serrated flange), ISO 4161, ANSI B18.2.2
Material	Carbon Steel (Grade 5, 8, 10), 304 Stainless Steel (A2), 316 Stainless Steel (A4)
Surface / Coating	Electroplated Zinc (Blue/White, Yellow/Color), Dacromet, Multi-Element Alloy Co-Permeation, Hot-Dip Galvanized, Plain/Black Oxide
Flange Type	Plain (smooth) or Serrated (anti-loosening teeth)
Flange Diameter	1.3d to 1.5d (where d = nominal thread diameter)

Surface Treatment & Zinc Coating Quality

Flange nuts are widely used in automotive and structural applications where the flange face contacts the workpiece directly, making surface coating quality critical for both corrosion protection and friction consistency:

• Hot-Dip Galvanizing (HDG) — Thick zinc layer (50-120μm) providing superior corrosion protection for outdoor structural flange nut applications. Compliant with ISO 1461 / ASTM A153. Note: HDG may affect serrated flange tooth engagement on hardened surfaces.
• Electroplated Zinc Blue-White (Zn Blue/White) — Bright silver-blue finish with 5-12μm zinc layer. Cr3+ trivalent passivation, RoHS compliant. The most common finish for automotive flange nuts — thin coating preserves flange flatness and serration effectiveness. Baked post-plating to prevent hydrogen embrittlement.
• Color Zinc / Yellow Zinc (Iridescent Passivation) — Golden-iridescent multi-colored passivation providing 150-250 hours salt spray resistance. Preferred for automotive and machinery flange nuts requiring enhanced corrosion protection with visual identification.
• Dacromet Coating — Water-based zinc-chromium flake coating with NO hydrogen embrittlement risk. 1,000+ hours salt spray resistance. Thin, uniform coating that does not affect flange flatness or serration engagement. The premium choice for high-strength flange nuts in automotive, railway, and heavy machinery applications.
• Multi-Element Alloy Co-Permeation — Zinc-aluminum-rare earth alloy layer providing 2,000+ hours salt spray resistance with self-healing properties. Used in critical infrastructure flange nuts for steel structures, power transmission, and coastal installations.

Key Features

• Integrated flange eliminates need for separate washer — faster assembly and lower part count
• Large bearing surface distributes load, prevents surface damage on soft materials
• Serrated flange variant provides vibration-resistant locking by biting into mating surface
• Hex top allows standard wrench/socket tightening
• Uniform clamping force — flange ensures perpendicular load distribution even on slightly uneven surfaces

Applications

• Automotive body and chassis assembly
• Steel structure and prefabricated building connections
• Industrial machinery and equipment manufacturing
• Railway and transit vehicle assembly
• Electrical enclosure and panel fastening

Why Choose BoltNutsPlus?

• ISO 9001:2015 Certified Manufacturing — consistent quality you can trust
• 15+ Years of Export Experience — serving 40+ countries worldwide
• Full Traceability — material certificates (EN 10204 3.1) and test reports included
• Custom Packaging & OEM/ODM — your brand, your specifications
• Third-Party SGS / Bureau Veritas Inspection Available
• 24-Hour Quote Response — same-day reply for urgent requirements