Hex Flange Nut, Thick

Our metric thick hex flange nuts feature an integrated wide-bearing flange beneath the hex body, distributing clamping load over a larger surface area than a standard hex nut. Available with serrated and non-serrated flange faces, thick hex flange nuts deliver superior vibration resistance and load distribution in automotive subframes, structural steel connections, and heavy industrial machinery.

What Are Thick Hex Flange Nuts?

Thick hex flange nuts are metric hex nuts with an integral circular flange formed beneath the nut body. The flange functions as a built-in washer, spreading the bearing load over a larger footprint to prevent surface indentation and reduce the risk of loosening in soft or thin substrates. The thick variant provides a greater thread engagement depth than standard hex flange nuts, increasing load capacity and resistance to stripping under high-torque installation. Serrated flange variants incorporate radial teeth on the bearing face that bite into the mating surface to provide positive anti-rotation locking under vibration. Thick hex flange nuts are a standard specification component in automotive exhaust systems, suspension brackets, engine mounts, structural steelwork, agricultural equipment, and heavy commercial vehicle assemblies.

Key Features and Benefits

• Integral Load-Spreading Flange: Eliminates the need for a separate flat washer by providing a built-in bearing surface that distributes clamping load and reduces substrate indentation.
• Serrated Locking Option: Radial serrations on the flange bearing face mechanically lock into the mating surface, providing positive vibration resistance without a separate locking element.
• Increased Thread Engagement: Greater axial body height compared to standard flange nuts provides higher resistance to thread stripping under elevated installation torque and dynamic loads.
• One-Piece Assembly Efficiency: Integral washer-nut design reduces component count, simplifies assembly, and eliminates washer misalignment or loss during installation.
• High Tensile Strength: Available in Grade 8 and Grade 10 alloy steel for high-strength bolted connections in structural and automotive driveline applications.

Materials and Finishes

• Carbon Steel (Zinc Plated): General industrial, automotive, and structural applications.
• Alloy Steel (Grade 8 / Grade 10): High-strength automotive, driveline, and structural steel connections.
• Stainless Steel (A2 / A4): Food processing, marine, and pharmaceutical environments.
• Hot-Dip Galvanised: Structural steel and outdoor infrastructure applications with extended corrosion life requirements.

Standards and Size Range

Thick hex flange nuts are manufactured to DIN 6923 (non-serrated) and ISO 4161 (serrated) standards. Available in M5 through M24 metric coarse thread, with selected fine-thread sizes available on request.

Frequently Asked Questions

1. What is the advantage of a hex flange nut over a standard hex nut with washer?

A hex flange nut combines the nut and washer into a single component, ensuring correct washer sizing, eliminating washer misalignment, reducing part count, and speeding up assembly — particularly in high-volume production and maintenance environments.

2. What is the difference between serrated and non-serrated hex flange nuts?

Serrated flange nuts incorporate radial teeth on the bearing face that bite into the mating surface to resist rotation under vibration. Non-serrated variants provide load spreading without surface engagement and are used where the mating surface finish must be preserved.

3. Are thick hex flange nuts suitable for automotive applications?

Yes. Thick hex flange nuts in Grade 8 or Grade 10 alloy steel are widely used in automotive exhaust systems, suspension brackets, engine mounts, and subframe connections where vibration resistance and high clamping loads are required.

4. What is the DIN standard for hex flange nuts?

Non-serrated hex flange nuts conform to DIN 6923. Serrated hex flange nuts conform to ISO 4161. Both standards specify flange diameter, nut height, thread tolerances, and bearing face geometry.

5. Can serrated hex flange nuts damage the mating surface?

Serrations are designed to bite into steel and similar hard surfaces. On soft materials such as aluminium, brass, or plastic, serrations may cause surface damage or pull-through. In these applications, non-serrated variants or standard hex nuts with separate washers are recommended.

6. What size range do you stock for thick hex flange nuts?

We stock thick hex flange nuts in M5 through M24 metric coarse thread in both serrated and non-serrated variants. Selected metric fine-thread sizes are available on request.

7. Are stainless steel hex flange nuts available?

Yes. A2 and A4 stainless steel hex flange nuts are available for marine, food processing, and corrosive environment applications.

8. What is the thread strength grade of your standard hex flange nuts?

Standard zinc-plated carbon steel hex flange nuts are supplied in Grade 8 (property class 8). Higher-strength Grade 10 alloy steel variants are available for heavy-duty structural and automotive applications.

9. Do thick hex flange nuts require a separate lock washer?

Serrated hex flange nuts provide self-locking action and do not require a separate lock washer. Non-serrated variants may be used with a spring washer or thread-locking compound in high-vibration applications.

10. Can hex flange nuts be used in structural steel connections?

Yes. Hot-dip galvanised thick hex flange nuts in appropriate strength grades are suitable for structural steel connections in construction and infrastructure. Confirm the required property class and coating specification with your structural engineer.