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Nuts · ASME B18.2.2 · Application guide

What Are Hex Coupling Nuts, UNC Used For?

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

Hex Coupling Nuts, UNC are used for inch hex coupling nuts with UNC thread for joining threaded rods. They are manufactured to ASME B18.2.2, 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
Inch hex coupling nuts with UNC thread for joining threaded rods
Governing standard
ASME B18.2.2
Screw size range
1 7/8" to #10
Category
Nuts

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

What Are Hex Coupling Nuts, UNC Used For? application image

Hex Coupling Nuts, UNC are used primarily for inch hex coupling nuts with UNC thread for joining threaded rods. This page lists the industries and assemblies where they are specified, the selection criteria that matter for each application, installation practice, and the cases where a different fastener type is the correct choice. Parts are supplied to ASME B18.2.2. Stocked across roughly 1 to 10, they cover general to heavy-duty work.

Typical Applications for Hex Coupling Nuts, UNC

The most common settings where these are specified:

  • Construction: rod hangers.
  • HVAC: supports.
  • Electrical: trapeze hangers.
  • Plumbing: pipe supports.

How to Specify Hex Coupling Nuts, UNC for Your Application

  • Size: Match the nominal size to the mating thread or hole. This product spans 1–10; 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 ASME B18.2.2. 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 Coupling Nuts, UNC

  • 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 Coupling Nuts, UNC 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 coupling nuts, UNC outside the standard range?

Thread, height, across-flats, property class, locking feature and flange form can all be varied, including thread sizes the standard series does not run to. 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 #6 Hex Coupling Nuts, UNC to ASME B18.2.2. Side view and top view, drawn to the dimensions in the table below and redrawn for any size selected.
Threads per inch
32
Width across flats s (in)
0.312
Nut height m (in)
0.5
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 (ASME B18.2.2)

SizeThreads per inchWidth across flats s (in)Nut height m (in)Reference standard
#6320.3120.5ASME B18.2.2
#8320.3120.625ASME B18.2.2
#10240.3120.75ASME B18.2.2
1/4"200.4381.75ASME B18.2.2
5/16"180.51.75ASME B18.2.2
3/8"160.5621.75ASME B18.2.2
7/16"140.6251.75ASME B18.2.2
1/2"130.6881.75ASME B18.2.2
9/16"120.8122.125ASME B18.2.2
5/8"110.8122.125ASME B18.2.2
3/4"1012.25ASME B18.2.2
7/8"91.252.5ASME B18.2.2
1"81.3752.75ASME B18.2.2
1 1/8"71.53ASME B18.2.2
1 1/4"71.6253ASME B18.2.2
1 1/2"623.5ASME B18.2.2
1 5/8"5.52.5624.875ASME B18.2.2
1 3/4"52.755.25ASME B18.2.2
1 7/8"52.9385.625ASME B18.2.2
2"4.53.1256ASME B18.2.2
2 1/4"4.53.56.75ASME B18.2.2
2 1/2"43.8757.5ASME B18.2.2
2 3/4"44.258.25ASME B18.2.2
3"44.6259ASME B18.2.2
3 1/4"459.75ASME B18.2.2
3 1/2"45.37510.5ASME B18.2.2
3 3/4"45.7511.26ASME B18.2.2
4"46.12512ASME B18.2.2
4 1/4"46.512.75ASME B18.2.2
4 1/2"46.87513.5ASME B18.2.2
4 3/4"47.2514.25ASME B18.2.2
5"47.62515ASME B18.2.2
5 1/4"4815.75ASME B18.2.2
5 1/2"48.37516.5ASME B18.2.2
5 3/4"48.7517.25ASME B18.2.2
6"49.12518ASME B18.2.2
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

What are Hex Coupling Nuts, UNC used for?

Inch hex coupling nuts with UNC thread for joining threaded rods. They are supplied to ASME B18.2.2.

Which industries use Hex Coupling Nuts, UNC?

They are commonly specified in construction, hvac and electrical, among other sectors.

How do I choose the right size of Hex Coupling Nuts, UNC?

Match the nominal size to the mating thread or hole. This product is available from 1 to 10; the full dimension table on this page lists each size.

Do Hex Coupling Nuts, UNC 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.

Can I get a quote for Hex Coupling Nuts, UNC 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.