Commercial 4.6 · Class 8.8 · Class 10.9 · Grade 5 & 8 · 304 & 316 Stainless · A2-50 · A2-70 · A4-50 · A4-70 · A4-80 · Bumax · Structural

Hex Bolts & Set Screws

Hex bolts and set screws for joining steel, bolting machinery and brackets, and structural connections, in every common grade and finish.

About the Hex Bolts & Set Screws

Hex bolts and set screws are the everyday nuts-and-bolts fastener, used for joining steel, bolting machinery and brackets, structural steel connections, trailers and general repairs. They come in class 4.6 commercial, class 8.8, 10.9 and 12.9 high tensile, imperial grade 5 and 8, AS/NZS 1252 and EN 14399 structural assemblies, and 304, 316 and high strength stainless, zinc plated, galvanised or plain, from M3 to M64 and in imperial sizes. Choose bolt only, bolt and nut, or a full assembly with washer above; the guide below covers grades, head markings and structural bolts.

Also called set screws, hex set screws, hex head bolts, hexagon bolts or high tensile bolts.

Features

Commercial to high-tensile: class 4.6, 8.8, 10.9
Stainless A2/A4 and Bumax 88/109 options
Standards AS 1110.1, AS 1111.1, ANSI B18.2.1
Plain, zinc-plated, galvanised, zinc flake or stainless finishes
Metric and imperial sizes
Coarse and fine-pitch threads

Applications

Joining steel plates, brackets and frames
Structural steel connections
Machinery assembly and repairs
Trailers, farm gear and general repairs

Hex bolt or set screw?

A hex bolt has a plain, unthreaded shank under the head and a set thread length (for bolts up to 125mm long, twice the diameter plus 6mm). A set screw is threaded almost to the head. In the selector, part thread is a bolt and full thread is a set screw.

For a joint carrying shear, use a bolt so the plain shank, not the thread, sits across the joint: the shank has more area, so it carries more load. A set screw's thread almost always crosses the joint and reduces its shear capacity. Set screws suit tapped holes, clamping and general fixing where the full thread is useful.

Bolt

Plain shank across the joint (red line)

Set screw

Thread across the joint: less shear capacity

Metric class 8.8

Class stamped on the head

Imperial grade 5 / 8

3 lines = grade 5, 6 lines = grade 8

Bolt grades and head markings

The grade is stamped on the head, so you can check a bolt on site.

Common bolt grades: head marking and minimum tensile strength.

Grade	Head marking	Min. tensile strength	Use
Class 4.6 (AS 1111.1)	4.6	400MPa	Commercial, general fixing
Class 8.8 (AS 1110.1)	8.8	800MPa (below M16), 830MPa (M16 up)	High tensile, structural and machinery
Class 10.9	10.9	1,040MPa	Higher strength machinery
Class 12.9	12.9	1,220MPa	Strongest metric class
Imperial grade 5	3 radial lines	120,000psi (to 1 inch)	Imperial high tensile
Imperial grade 8	6 radial lines	150,000psi	Strongest imperial grade
Stainless A2-70 / A4-70	A2-70 / A4-70	700MPa (to M20)	Corrosion resistance
Stainless A4-80	A4-80	800MPa	High strength stainless

Structural bolts: AS/NZS 1252 and EN 14399

AS/NZS 1252:2016 K0 class 8.8 HR structural assemblies: a matched bolt, nut and washer tested together in a mandatory assembly test, which gives a reliable indication of how a batch will perform. They replace the old AS 1252:1983 bolts.
EN 14399 K2 assemblies: supplied for tensioning, where the engineer specifies a pretensioned joint.
ASTM A325 weathering steel assemblies for weathering steel structures.
Snug tight and fully tensioned are tightening procedures and joint types set by the engineer, not different bolts. Use the assembly and tightening method on the drawings.

Finishes

Zinc plated: dry and indoor use.
Hot dip galvanised: outdoor steel and timber, with galvanised nuts made to suit.
Plain (self colour): oiled, for machinery and where it will be painted.
304 and 316 stainless: wet, food and coastal areas; 316 near the sea. Neptune 316 bolts are A4-80, and BUMAX high strength stainless (A4-80 and A4-100) is for demanding uses.
Also zinc flake, weathering steel, brass and nylon.

Hex bolts in Adelaide

Allmat supplies hex bolts, set screws, structural assemblies, nuts and washers to builders, fabricators, fitters and farmers across Adelaide and South Australia. Send your bolt list and we will price the lot.

Hex bolts for site, workshop and farm

Hex bolts, set screws, structural assemblies, nuts and washers in every common grade and finish are available to order from Allmat for builders, steel fabricators, fitters, farmers and trade across Adelaide and South Australia. Order through Allmat, we pick and pack it, then click and collect from the Allmat yard or have it delivered to site.

Send your list for a quote Call 1300 03 03 63

Goes with

Questions

What is the difference between a hex bolt and a set screw?

A hex bolt has a plain shank and a limited thread length; a set screw is threaded almost to the head. Use bolts for joints that carry shear.

Why do engineers specify bolts, not set screws?

A bolt has a plain shank under the head. In a joint carrying shear, the plain shank should sit across the joint: it has more area than the thread, so it carries more load. A set screw (sometimes called a screw bolt) is threaded almost to the head, so its thread crosses the joint and reduces the shear capacity. Set screws suit joints that only clamp in tension, tapped holes and general fixing where the full thread is needed. Always follow the engineer's specification.

Is a set screw the same as a grub screw?

Not in Australia. Here a set screw (setscrew) is a hex head screw threaded almost to the head, which this page carries in every grade. In the US a set screw means a headless grub screw; those are on our grub screws page.

What is the difference between 8.8 and 10.9 bolts?

Class 8.8 has a minimum tensile strength of 800MPa (830MPa from M16); class 10.9 has 1,040MPa. The class is stamped on the head.

What do the lines on a bolt head mean?

On imperial bolts, 3 radial lines mean grade 5 and 6 radial lines mean grade 8. Metric bolts are stamped with their class, such as 8.8 or 10.9, and stainless with A2 or A4.

Are stainless steel bolts as strong as high tensile?

Standard A2-70 and A4-70 stainless (up to M20) has a minimum tensile strength of 700MPa, less than class 8.8. A4-80 stainless reaches 800MPa.

What is the difference between snug tight and fully tensioned bolts?

They are tightening procedures, not bolt types. The engineer specifies which, and the bolt assembly to use, for each structural joint.

Where can I buy hex bolts in Adelaide?

Order through Allmat. Send your bolt list or order ahead by phone on 1300 03 03 63, then click and collect from 25 Kapara Road, Gillman, or have them delivered to site.

Hex Bolts & Set Screws: sizes and finishes we supply

8,014 lines by type and finish. Pick one above for its product code, pack sizes and dimensions.

Type	Finish	Size (diameter)	Lengths	Lines
Standard hex	Zinc Plated	M5, M6, M8, M8-1.00, M10, M10-1.25, M12, M12-1.25, M12-1.50, M14, M14-1.50, M16, M16-1.50, M18, M18-1.50, M20, M20-1.50, M22, M24, M24-1.50, M24-2.00, M27, M30, M36	10 to 375 (44 lengths)	1691
Standard hex	316 Stainless	M4, M5, M6, M8, M10, M12, M14, M16, M18, M20, M22, M24, M27, M30, M33, M36, M39, M42	6 to 800 (64 lengths)	1286
Standard hex	Galvanised	M6, M8, M10, M12, M16, M20, M22, M24, M27, M30, M33, M36, M42, M48	12 to 1500 (82 lengths)	1153
Standard hex	Steel	M6, M8, M8-1.00, M10, M10-1.25, M12, M12-1.25, M12-1.50, M14, M14-1.50, M16, M18, M20, M22, M24, M27, M30, M33, M36, M42, M48, M64	16 to 450 (48 lengths)	1097
Standard hex	Steel	1/4, 5/16, 3/8, 7/16, 1/2, 9/16, 5/8, 3/4, 7/8, 1, 1-1/8, 1-1/4, 1-3/8, 1-1/2, 1-3/4, 2, 1-14	1/2 to 20 inch (36 lengths)	881
Standard hex	Zinc Plated	1/4, 5/16, 3/8, 7/16, 1/2, 9/16, 5/8, 3/4, 7/8, 1, 1-1/8, 1-1/4, 1-1/2, 1-14	1/2 to 16 inch (30 lengths)	657
Standard hex	304 Stainless	M3, M4, M5, M6, M8, M10, M12, M14, M16, M18, M20, M24	6 to 425 (44 lengths)	328
Standard hex	316 Stainless	3/16, 1/4, 5/16, 3/8, 7/16, 1/2, 5/8, 3/4, 7/8, 1	1/2 to 8-1/2 inch (24 lengths)	192
Standard hex	304 Stainless	3/16, 1/4, 5/16, 3/8, 7/16, 1/2, 5/8, 3/4, #8, #10	3/8 to 7 inch (21 lengths)	191
Standard hex	Zinc Flake Silver	M6, M8, M10, M12, M16, M18, M20, M24, M30, M36, M42, M48	16 to 340 (33 lengths)	106
Standard hex	Nylon Natural	M3, M4, M5, M6, M8, M10, M12, M16, M20, M24	6 to 100 (19 lengths)	105
Flanged	Steel	M6, M8, M10, M12, M14, M16, M20	12 to 100 (15 lengths)	57
Flanged	Zinc Flake Silver	M8, M10, M12, M14, M16, M20	16 to 100 (14 lengths)	42
Standard hex	Nylon Natural	1/4, 5/16, 3/8, 1/2	1/2 to 4 inch (11 lengths)	33
Standard hex	Weathering Steel	M24, M30, M36	60 to 260 (22 lengths)	31
Flanged	Zinc Plated	M5, M6, M8, M10, M20	10 to 70 (11 lengths)	29
Standard hex	Galvanised	1/2, 5/8, 3/4	1 to 6 inch (11 lengths)	27
Flanged	Zinc Yellow Passivate	M5, M6, M8, M10, M12	12, 16, 20, 25, 30, 35, 40, 50	23
Heavy hex	Steel	5/8, 3/4, 7/8, 1, 1-1/8, 1-1/4	50 to 120mm (11 lengths)	22
Flanged	Steel	1/2, 5/8	1-1/4, 1-1/2, 1-3/4, 2, 2-1/4, 2-1/2, 3 inch	19
Flanged	304 Stainless	M6, M8, M10, M12	16, 20, 25, 30, 40	13
Flanged	Galvanised	M8, M10, M20	16, 20, 25, 30, 40, 50, 60, 70	9
Standard hex	Nylon Black UV Stable	M8, M10	20, 25, 30, 40, 50	7
Standard hex	Brass	M5, M6	12, 16, 20	6
Standard hex	Zinc Flake Silver	9/16, 5/8, 3/4	1-1/4, 1-3/4, 2-1/2, 3-1/4, 4, 4-1/2 inch	6
Standard hex	Duplex Stainless	M16	130, 140	2
Standard hex	Zinc Yellow Passivate	M20	125	1

Data sheets and documents

The documents for the product you choose are listed with the selector above. Here is every Hex Bolts & Set Screws document from Hobson Engineering.

All Hex Bolts & Set Screws documents (86)

Data sheets and technical data (31)

Standards (3)

Did You Know flyers (27)

Guides and articles (25)

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Add the sizes you need to your quote, or send us your list and we’ll price the lot and supply it with the rest of your order.

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