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3/8 x 24 TPI UNF Fine Zine Grade 8 Hex Flange Serrated Nuts High Tensile IFI 145 / B18 2.2

As low as $0.102 /each

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SKU: 41FLF38

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$100 to $249
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Matching Parts

Technical Specifications

Thread Pitch Chart.pdf Imperial vs Metric Strength Chart.pdf Nut Mechanical Properties.pdf

More Information
System of Measurement	Imperial
Product	Flange Serrated Nut
Size	3/8"
Size & Thread Pitch	3/8" x 24 TPI UNF
Thread Pitch	24 TPI
Thread	Fine
Thread Direction	Right Hand
Corrosion Protection Level	Moderate
Class Grade	High Tensile Grade 8
Material	Carbon Steel
Finish	Zinc Plated
Across Flats (af)	0.551 - 0.562" (14.00 - 14.28mm)
Across Corners (ac)	0.628 - 0.650" (15.96 - 16.51mm)
Flange Diameter (f)	0.728 - 0.750" (18.50 - 19.05mm)
Nut Height Overall (b)	8.38 - 8.81mm
Hex Height (h)	0.230" (5.85mm)
Serrations under Head	Yes
Spanner Size (af)	9/16"
Closest size in mm	M10 (10mm)
Standard Made To	IFI 145 / B18 2.2
Brand	Hobson Engineering
Alternative Brands	Bolt and Nut Australia

Dimensional data is a guide only. Tolerance differences exist between brands and batches

Description

3/8" x 24 TPI UNF Fine Hex Flange Nuts are hex nuts with an integrated washer face on the bearing side, removing the need for a separate washer.

About Hex Flange Nuts

Hex Flange Nuts have a six-sided body with an integrated washer face on the bearing side. The flange spreads load like a separate washer and removes a part from the assembly. Serrated variants have small teeth on the underside of the flange that bite into the mating surface and resist loosening from vibration. Common in automotive, machinery and high-vibration metal-to-metal joints.

Recommended use Indoor and dry-environment use only. Common in automotive, machinery and electrical assembly where the bolt is not exposed to weather, condensation or wet service.

Not sure what nut you have?

Two ways to identify it - whichever is easier with what is in front of you.

1If you have the nut

Find the spanner that fits it snugly, then measure the hole. Our nut identification chart lists every metric and imperial nut we stock side by side, sorted by spanner size.

Open the nut identification chart ›

2If you have its bolt

The fastest check is the male thread: the right nut spins onto its bolt by hand with no force. Identify the bolt size and pitch first with our bolt and screw guide, and the nut follows.

Open the bolt and screw guide ›

Also known as

Hex Flange Nuts · Flange Serrated Nuts · Flange Head Nuts · Frame Nuts · Whiz Nuts

Pairs with

Matching Hex Flange Bolts · Matching Hex Bolts

Frequently Asked Questions

What bolt does this nut fit?

Any bolt with a matching 3/8" x 24 TPI.

The nut must match the bolt's diameter AND pitch (metric) or TPI (imperial). A 3/8" x 24 TPI nut will not engage a bolt with a different pitch, even when the diameter is the same. Strength class of the nut should equal or exceed the bolt class.

What strength class is this?

Refer to the product title for the property class and the head marking for the grade.

See the head marking chart and full strength table on our site for the full conversion table.

What standard is this manufactured to?

Manufactured to IFI 145 / B18 2.2.

Standards specify the nut's head dimensions, thread tolerance, and minimum strength class. Always pair the nut with a bolt to the equivalent standard for a guaranteed fit.

What spanner / socket size do I need?

Spanner / socket size: 9/16".

Drive these with a matching spanner, socket or driver bit. Using an oversized tool will round off the head.

Where are these nuts typically used?

Anywhere a matching bolt needs to be clamped down: machinery assembly, structural connections, brackets, fittings.

Nuts are the half of the bolted joint that lets it come apart again. Match diameter, pitch and class to the bolt; add a flat washer under the nut to spread load on the clamped face.

Material & Coating

Zinc Electroplated zinc on carbon steel. A thin (5 to 12 micron) bright (clear-passivated) zinc layer applied by electrolysis. Bright silvery finish.

Important NOT suitable for outdoor, wet, marine or treated-timber applications. The thin coating is consumed quickly by rainwater or treated-pine preservatives. For outdoor use, specify hot-dip galvanised.

Grade Imperial fasteners are classified as grade 2, 5, 8, 9, 10, 12. See the head marking chart and full strength table.

Thread Pitch & Terminology

Thread Pitch (Imperial) Imperial fasteners measure thread pitch as TPI (threads per inch), the number of thread peaks per inch of fastener length. Imperial systems include UNC (coarse), UNF (fine), BSW (Whitworth) and BSF (British Standard Fine). This product has 24 TPI, meaning 24 thread peaks per inch.

How to Measure

A nut is named after the bolt it fits. An M10 nut fits an M10 bolt - the 10mm is the bolt's diameter, not anything on the nut itself.

The two quick checks are the spanner size across the flats, and the hole, which always measures smaller than the named size (an M10 nut reads about 8.5mm through the hole).

The most reliable test of all: thread it onto a bolt you know. The right nut spins on by hand with no force.

Resources

Technical library PDFs

For full technical data including key product information, range and a CAD drawing, see our Technical PDFs library.

Measurement conversion calculators

Convert between metric and imperial sizes, gauge to mm, decimal to fraction and TPI to pitch with our measurement conversion calculators.

Pricing & Delivery

Includes GST, a Tax Invoice and Free Standard Delivery anywhere in Australia.

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Disclaimer

Technical data Researched and compiled from numerous industry sources for the sole purpose of providing basic information. All material is advisory only and its use by anyone is entirely voluntary. Reliance on it for any purpose by anyone is at the sole risk of that person, and Bolt and Nut Australia is not responsible for any loss, claim or damages arising therefrom. In developing this information, Bolt and Nut Australia has made a determined effort to present it accurately.

Measurements Sizes are taken from supplier catalogues or hand-measured and should be used as a guide. Minor variation between batches is normal. Stock is sourced from various suppliers, so differences may exist between batches in thread length, markings, appearance or finish.

Product Photos & PDF Data Sheets Represent the product type, not exact size. PDFs are a reference guide only. Specifications may change without notice.

If you see any problems with any of our specifications or you require additional information please contact us.

Delivery

Orders UNDER $30

Weigh less than 500grams

Exceptions: Tools, Kits, Bulky items = Sent as a parcel with tracking

Small orders that fit into the slot of your Letterbox are sent:

FREE with Aust Post Letter delivery with NO TRACKING and delivery between 4-12 business days

Select a Quicker delivery service

$7.00 Parcel Delivery 2-7 business days
From $12.00 Express Delivery 1-4 business days
From $14.00 StarTrack PREMIUM Express Delivery 1-3 business days

Click & Collect - Warehouse pickup

Unit 9, 93 Rivergate Place, Murarrie, QLD

Place your order online and we will have it ready within 2 hours. Call if required sooner
Pickup times between 8am - 4pm, Monday - Friday

Orders OVER $30

Weigh more than 500grams

Included is orders under $30 but weigh more than 500grams or wont fit in the slot of your letterbox

Including Large and Bulky heavy orders are sent:

FREE as a Parcel Delivery WITH TRACKING and delivery between 2-7 business days

Select an Express delivery service

From $12.00 Express Delivery 1-4 business days
From $14.00 StarTrack PREMIUM Express Delivery 1-3 business days

Click & Collect - Warehouse pickup

Unit 9, 93 Rivergate Place, Murarrie, QLD

Place your order online and we will have it ready within 2 hours. Call if required sooner
Pickup times between 8am - 4pm, Monday - Friday

All delivery dates are estimated and depend on stock availability, delivery location, service chosen, size of order, time of year, when order was placed e.g long weekends or sale periods.

Further delivery information can be found on our Delivery page

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Supplier Details

MPN	NFG8ZF037
UPC	9314818388641