MF FASTENER INDUSTRIES LLC Manufacturer of anchor bolts, studs & plate washers · Importer & stockist of fasteners

Technical datasheet ASTM A563 / A563M — Heavy hex structural nut

Reference only — for design, verification or contractual purposes refer to the current issue of the original standard. MF Fastener Industries LLC · sales@mfindllc.com · +971 6 767 2469 · mfindllc.com

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Dimensional datasheet

ASTM A563 heavy hex nut

Heavy hexagon nut for structural bolting. Thicker and wider across flats than a standard hex nut, so it develops the full strength of the bolt. Graded to match A325 and A490.

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d nominal thread diameters width across flatse width across cornersm nut height

Dimensions

inches

Imperial sizes, UNC thread, dimensions to ASME B18.2.6. A heavy hex nut is not interchangeable with a standard hex nut — it is wider and thicker.

Size	Threads/in	s — across flats	Spanner size	m — nut height
1/2"	13 UNC	7/8"	7/8"	31/64"
5/8"	11 UNC	1-1/16"	1-1/16"	39/64"
3/4"	10 UNC	1-1/4"	1-1/4"	47/64"
7/8"	9 UNC	1-7/16"	1-7/16"	55/64"
1"	8 UNC	1-5/8"	1-5/8"	63/64"
1-1/8"	7 UNC	1-13/16"	1-13/16"	1-7/64"
1-1/4"	7 UNC	2"	2"	1-7/32"
1-3/8"	6 UNC	2-3/16"	2-3/16"	1-11/32"
1-1/2"	6 UNC	2-3/8"	2-3/8"	1-15/32"

Grade must match the bolt

A325: Grade C or DH. A490: Grade DH only. Grade DH3 and C3 are the weathering steel equivalents for Type 3 bolts.

An under-graded nut strips before the bolt reaches its design load, and the joint never achieves the clamp force the engineer specified.

Galvanized nuts are tapped oversize

A galvanized nut is tapped after coating to clear the zinc on the bolt thread, then lubricated. It must be used with the galvanized bolt it was supplied with.

A plain nut will not run onto a galvanized bolt. A galvanized nut on a plain bolt is a loose fit with unreliable clamp load.

Metric — A563M

ASTM A563M

Size	Pitch	s — across flats	Spanner size	m — nut height
M16	2.00	27 mm	27 mm	17.1 mm
M20	2.50	34 mm	34 mm	20.7 mm
M22	2.50	36 mm	36 mm	23.6 mm
M24	3.00	41 mm	41 mm	24.2 mm
M27	3.00	46 mm	46 mm	27.6 mm
M30	3.50	50 mm	50 mm	30.7 mm
M36	4.00	60 mm	60 mm	36.6 mm

Metric grades are 8S and 10S, with 8S3 and 10S3 for weathering steel. 8S pairs with A325M; 10S pairs with A490M.

Grades

A563 / A563M

Grade	Proof load stress	Hardness	Pair with
A	—	Low carbon	A307 Grade A only
C	144 ksi	78 – 95 HRB	A325 Type 1
C3	144 ksi	78 – 95 HRB	A325 Type 3, weathering
DH	175 ksi	24 – 38 HRC	A325 and A490
DH3	175 ksi	24 – 38 HRC	A490 Type 3, weathering
8S / 10S (metric)	830 / 1040 MPa	—	A325M / A490M

Grade is marked on the nut face. Where a specification is silent, Grade DH is the safe choice for structural work — it suits both A325 and A490.

At a glance

Standard	ASTM A563 · A563M
Form	Heavy hexagon, chamfered
Thread	UNC imperial · metric coarse
Grades	A · C · C3 · DH · DH3 · 8S · 10S
For A325	Grade C or DH
For A490	Grade DH
Matching washer	ASTM F436 / F436M
Standard hex equivalent	DIN 934 · ISO 4032 — not a substitute

Supply

Imported and held in stock, sourced from established mills and supplied from our warehouse in Umm Al Quwain.

Anchor bolts, studs and plate washers are manufactured at our own plant. This item is not.

Finish

Plain	Black, oiled
Hot-dip galvanized	Oversize tapped and lubricated, supplied as an assembly
Certification	Mill certificate against lot and heat number

Testing

Dimensional and thread inspection is carried out in our own plant on calibrated instruments. Tensile, hardness and chemical testing is carried out by independent UAE-accredited laboratories.

Reference only

This datasheet is published for reference. Dimensions and property values are reproduced in good faith from published standards, but for design, verification or contractual purposes always refer to the current issue of the original standard.

If a figure here conflicts with the standard, the standard governs.

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Send the size, grade, finish and quantity, and the bolt grade you are pairing with so we can confirm the nut suits.