ASTM A563

The ASTM A563 specification covers the chemical and mechanical requirements for carbon and alloy steel nuts used on bolts, studs, and externally threaded fasteners. The charts below address over tapping allowances for hot-dip galvanized nuts, grade marking requirements, and mechanical requirements. For information on suitable nuts for various grades of bolts, visit the Nut Compatibility Chart.
According the A563 specification, “The requirements for any grade of nut may, at the supplier’s option, and with notice to the purchaser, be fulfilled by furnishing nuts of one of the stronger grades specified herein unless such a substitution is barred in the inquiry and purchase order”. This is important because some nut grades are not readily available in certain sizes and finishes. Additionally, the specification allows for the substitution of ASTM A194 grade 2H nuts in lieu of A563 grade DH nuts due to the lack of availability of grade DH nuts in nominal sizes ¾” and larger.
Hot-dip galvanized nuts must be tapped oversize to allow for the added thickness of the zinc on the threads of the externally threaded fastener.
Various nut styles exist and to some degree are determined by their grade. These styles include hex, heavy hex, square, jam, coupling, and sleeve.

Scope

Standard specification for carbon and alloy steel nuts.

Grades

A	Low carbon steel, hex or heavy hex
B	Low carbon steel, hex or heavy hex
C	Carbon steel, quenched and tempered, heavy hex
D	Carbon steel, quenched and tempered, heavy hex
DH	Carbon steel, quenched and tempered, heavy hex
C3	Weathering steel, quenched and tempered, heavy hex
DH3	Weathering steel, quenched and tempered, heavy hex

MECHANICAL PROPERTIES

Grade	Style	Size, in.	Proof Load, ksi		Hardness, HBN
			Black	Galvanized
A	Hex	1/4 - 1-1/2	90	68	116 - 302
	Heavy Hex	1/4 - 4	100	75	116 - 302
B	Heavy Hex	1/4 - 1	133	100	121 - 302
	Heavy Hex	1-1/8 - 1-1/2	116	87	121 - 302
C / C3	Heavy Hex	1/4 - 4	144	144	143 - 352
D	Heavy Hex	1/4 - 4	150	150	248 - 352
DH / DH3	Heavy Hex	1/4 - 4	175	150	248 - 352
For UNC, 8UN, 6UN, and Coarse Pitch Threads ASTM A563 Nut Compatibility Chart Download a print version Grade of Bolt Surface Finish Nominal Size Inches A563 Grade and ANSI Nut Style Recommended Suitable Hex Heavy Hex Hex Heavy Hex A307 Grade A & C Any ¼ to 1½ A B,D,DH A,B,C,D,DH,DH3 >1½ to 2 A A C,D,DH,DH3 >2 to 4 A C,D,DH,DH3 A307 Grade B Any ¼ to 1½ A B,D,DH A,B,C,D,DH,DH3 >1½ to 2 A A >2 to 4 A A325 Type 1 Plain ½ - 1½ C C3,D,DH,DH3 Galvanized ½ - 1½ DH A325 Type 3 Plain ½ - 1½ C3 DH3 A354 Grade BC Plain ¼ to 1½ C D,DH C3,D,DH,DH3 >1½ to 4 C C3,D,DH,DH3 Galvanized ¼ to 1½ DH >1½ to 4 DH A354 Grade BD Plain ¼ to 1½ DH DH D,DH,DH3 >1½ to 4 DH DH3 A449 Plain ¼ to 1½ B D,DH B,C,C3,D,DH,DH3 >1½ to 3 A C,C3,D,DH,DH3 Galvanized ¼ to 1½ DH D,DH D >1½ to 3 DH D A490 Type 1 Plain ½ - 1½ DH DH3 A490 Type 3 Plain ½ - 1½ DH3 A687 Plain ⅝ - 3 D DH,DH3 Galvanized ⅝ - 3 DH F1554 Grade 36 Any ¼ to 1½ A B,D,DH A,B,C,D,DH,DH3 >1½ to 4 A C,D,DH,DH3 F1554 Grade 55 Plain ¼ to 1½ A B,D,DH A,B,C,D,DH,DH3 >1½ to 4 A C,D,DH,DH3 Galvanized ¼ to 4 A C,D,DH,DH3 F1554 Grade 105 Plain ¼ to 1½ D DH,DH3 >1½ to 3 DH DH3 Galvanized ¼ to 3 DH DH3 1. The availability of A563 grade DH nuts in nominal sizes 3/4" and larger is very limited and generally available only on special orders of 50,000 or more. For smaller quantities, ASTM A194 grade 2H should be considered. Source: http://www.portlandbolt.com