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Nuts · ISO 21670 · Application guide

What Are Hex Weld Nuts with Flange Used For?

Typical applications, the industries that specify hex weld nuts with flange, and how to choose the right size, material and finish for the joint.

Hex Weld Nuts with Flanges are used for a hex weld nut with a flange that is welded to sheet to give a strong, well-located thread. They are manufactured to ISO 21670, and the choice of size, property class and finish is driven by the load in the joint and the environment it sits in.

Primary duty
A hex weld nut with a flange that is welded to sheet to give a strong, well-located thread
Governing standard
ISO 21670
Thread size range
M5 to M16x1.5
Category
Nuts

Application notes are general engineering guidance. Verify the property class and any approval requirement against your own design calculation.

What Are Hex Weld Nuts with Flange Used For? application image

Application guide for Hex Weld Nuts with Flanges to ISO 21670. The core duty of the type is a hex weld nut with a flange that is welded to sheet to give a strong, well-located thread. The typical industries, the how-to-specify checklist, assembly practice and the exclusion cases are set out below. Stocked across roughly M5 to M16, they cover general to heavy-duty work.

Typical Applications for Hex Weld Nuts with Flange

The most common settings where these are specified:

  • Automotive assembly: chassis and body brackets.
  • Appliance frames: threaded points in steel sheet.
  • Racking: weld-nut fixing points.
  • Machinery housings: threads in thin plate.

How to Specify Hex Weld Nuts with Flange for Your Application

  • Size: Match the nominal size to the mating thread or hole. This product spans M5–M16; check the full table below for the exact dimensions of each size.
  • Locking & grade: Match the strength grade to the bolt, and choose a locking style (nyloc, all-metal, serrated flange) if the joint sees vibration.
  • Environment: For damp, coastal or chemical exposure prefer A4/316 stainless or a suitable coating; indoors, plated steel or A2 is usually sufficient.
  • Standard: This product is supplied to ISO 21670. Quoting the standard on your order guarantees interchangeable dimensions between suppliers.

Installation & Assembly Practice

  • Run the nut down by hand before applying the wrench to catch cross-threading early.
  • Tighten the nut rather than the bolt head where access allows — the torque-to-preload relation is more consistent.
  • For locking styles, note that nyloc inserts are single-use in critical joints and lose grip above roughly 120 °C.

Common Selection Mistakes with Hex Weld Nuts with Flange

  • Pairing a high-class bolt with a lower-class nut — the nut strips before the bolt reaches proof load; the nut class must meet or exceed the bolt class.
  • Using a plain nut with a spring washer in severe vibration instead of a prevailing-torque locking nut.
  • Re-using nyloc nuts in critical joints.

Where Hex Weld Nuts with Flange Are Not the Right Choice

Not on their own — they need a matching bolt or stud — and a plain nut is not a substitute for a locking type under heavy vibration.

Custom manufacturing · Made to drawing

Need a hex weld nuts with flange outside the standard range?

Height and across-flats are the two most often changed — a thinner nut for clearance, a larger hex for a tool that is already on the line. Made by cold heading or tapping.

Minimum order from 2,000 pieces; samples within 7 days of drawing approval.

Custom nut manufacturingSend a drawing

Technical Drawing

Customize the parameters below — every spec field is editable, and the drawing redraws to match the values you choose. Changing the size will snap the other fields to that size's standard values; you can then override any individual value.

Dimensioned line drawing of M5 Hex Weld Nuts with Flange to ISO 21670. Side view and top view, drawn to the dimensions in the table below and redrawn for any size selected.
Pitch P (mm)
0.8
b (mm)
2.2
c (mm)
0.8
d_a (mm)
6
d_c (mm)
15.5
Width across corners e (mm)
8.2
f (mm)
1.7
g (mm)
4
m_min (mm)
4.7
Nut height m (mm)
5
Width across flats s (mm)
8
r_1 (mm)
0.6
Sends the selected values to the quote form below.

Request a Quote

The form below follows the current technical drawing configuration. Change the drawing values above and the request details update automatically.

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Specification
Business Information

Dimensions & Specifications (ISO 21670)

SizePitch P (mm)b (mm)c (mm)d_a (mm)d_c (mm)Width across corners e (mm)f (mm)g (mm)m_min (mm)Nut height m (mm)Width across flats s (mm)r_1 (mm)r_2 (mm)m1000 (mm)Reference standard
M50.82.20.8615.58.21.744.7580.60.32.9ISO 21670
M612.70.8718.510.6256.647100.60.55.7ISO 21670
M81.252.719.522.513.62.569.6410130.80.812.2ISO 21670
M8x112.719.522.513.62.569.6410130.80.812.2ISO 21670
M101.52.951.211.526.516.93712.5713161121.8ISO 21670
M10x1.251.252.951.211.526.516.93712.5713161121.8ISO 21670
M10x112.951.211.526.516.93712.5713161121.8ISO 21670
M121.753.21.21430.519.43814.57151811.229.4ISO 21670
M12x1.51.53.21.21430.519.43814.57151811.229.4ISO 21670
M12x1.251.253.21.21430.519.43814.57151811.229.4ISO 21670
M1423.451.21633.522.44816.16172111.245.8ISO 21670
M14x1.51.53.451.21633.522.44816.16172111.245.8ISO 21670
M1623.71.21836.5254818.6619.52411.263.1ISO 21670
M16x1.51.53.71.21836.5254818.6619.52411.263.1ISO 21670
Inside the plant

Manufactured in our own plant

This part is cold-formed, threaded, heat-treated and finished in-house. The stages below are where its class and finish are actually decided.

  1. Wire rod feeding into a cold heading machine
    01

    Cold heading

    Wire rod is drawn to size and cold-formed into blanks. Forming rather than cutting keeps the grain flow continuous around the head, which is where a bolt is most likely to fail.

    Head dimensions and under-head radius checked at set-up and per shift.

  2. Thread rolling machine producing bolt threads
    02

    Thread rolling

    Threads are rolled between hardened dies rather than cut. Rolled threads are stronger in fatigue than cut threads and hold pitch and flank angle far more consistently across a batch.

    Go / no-go ring gauges to ISO 965 tolerance class 6g.

  3. Baskets of bolts staged for heat treatment
    03

    Heat treatment

    Quench-and-temper brings carbon and alloy steel to the property class ordered — 8.8, 10.9 or 12.9 — with the furnace charge tracked so a finished lot can be traced back to it.

    Core hardness and tensile tested per lot to ISO 898-1.

  4. Zinc plated bolts in a treatment basket
    04

    Surface treatment

    Zinc, zinc-nickel, hot-dip galvanizing, black oxide, phosphate and Dacromet, selected against the service environment rather than against the price list.

    Coating thickness and neutral salt spray hours to ISO 9227.

Frequently Asked Questions

Do Hex Weld Nuts with Flange need a locking feature?

If the joint sees vibration or cyclic load, use a locking style (nyloc, all-metal lock, or serrated flange) or a thread-locking adhesive. For static joints a standard nut tightened correctly is usually sufficient.

What material should Hex Weld Nuts with Flange be for outdoor use?

For damp, coastal or chemical environments specify A4 (316) stainless or a suitably coated steel. For indoor or dry use, A2 (304) stainless or zinc-plated steel is normally adequate.

Are Hex Weld Nuts with Flange made to a recognized standard?

Yes — they are manufactured to ISO 21670, so dimensions are interchangeable between suppliers when you quote the standard on your order.

What are Hex Weld Nuts with Flange used for?

A hex weld nut with a flange that is welded to sheet to give a strong, well-located thread. They are supplied to ISO 21670.

Can I get a quote for Hex Weld Nuts with Flange in the size and material I need?

Yes. Use the technical drawing and quote form on this page to set the size and options, then send the exact configuration to our team for pricing and lead time.