Nuts
The recommended nut specification for A307 is ASTM A563 Grade A. This is a low-strength steel nut that can be made in either hex or heavy hex patterns. For A307 grades A and C the recommended nut pattern is finished hex up through 1-1/2” in diameter. Above 1-1/2” diameter the nuts should be a heavy hex pattern. For A307 Grade B, all nuts are to be heavy hex pattern no matter the diameter.
| Nuts |
Washers |
| A307 Grades A & C* |
A307 Grade B |
| 1/4 – 1-1/2 |
1-5/8 – 4 |
1/4 – 4 |
| A563A Hex |
A563A Heavy Hex |
A563A Heavy Hex |
Unspecified |
Mechanical Properties
| Grade |
Style |
Size, in. |
Proof Load, ksi |
Hardness, HBN |
| Plain |
Galvanized |
| A |
Hex |
1/4 – 1-1/2 |
90 |
68 |
116 – 302 |
| Heavy Hex |
1/4 – 4 |
100 |
75 |
116 – 302 |
Chemical Properties
| Element |
Grade A |
| Carbon |
0.55% max |
| Manganese, min |
|
| Phosphorus, max |
0.12% |
| Sulfur, max |
0.15%* |
| * Sulfur content of 0.23% max is acceptable with the purchasers approval |
Dimensions
Click table to show drawing
| Nominal Size |
F |
C |
H |
Part Numbers |
| Width Across Flats |
Width Across Corners |
Thickness |
Domestic |
Import |
| Basic |
Max |
Min |
Max |
Min |
Basic |
Max |
Min |
Plain |
Galvanized |
Plain |
Galvanized |
| 1⁄2 |
3⁄4 |
0.750 |
0.736 |
0.866 |
0.840 |
7⁄16 |
0.448 |
0.427 |
16270 |
16271 |
11701 |
11702 |
| 5⁄8 |
15⁄16 |
0.938 |
0.922 |
1.083 |
1.051 |
35⁄64 |
0.559 |
0.535 |
16272 |
16273 |
11703 |
11704 |
| 3⁄4 |
11⁄8 |
1.125 |
1.088 |
1.299 |
1.240 |
41⁄64 |
0.665 |
0.617 |
16274 |
16275 |
11705 |
11706 |
| 7⁄8 |
15⁄16 |
1.312 |
1.269 |
1.516 |
1.447 |
3⁄4 |
0.776 |
0.724 |
16276 |
16277 |
11707 |
11708 |
| 1 |
11⁄2 |
1.500 |
1.450 |
1.732 |
1.653 |
55⁄64 |
0.887 |
0.831 |
16278 |
16279 |
11709 |
11710 |
| 11⁄8 |
111⁄16 |
1.688 |
1.631 |
1.949 |
1.859 |
31⁄32 |
0.999 |
0.939 |
16280 |
16281 |
11711 |
11712 |
| 11⁄4 |
17⁄8 |
1.875 |
1.812 |
2.165 |
2.066 |
11⁄16 |
1.094 |
1.030 |
16282 |
16283 |
11713 |
11714 |
| 13⁄8 |
21⁄16 |
2.062 |
1.994 |
2.382 |
2.273 |
111⁄64 |
1.206 |
1.138 |
– |
– |
11715 |
11716 |
| 11⁄2 |
21⁄4 |
2.250 |
2.175 |
2.598 |
2.480 |
19⁄32 |
1.317 |
1.245 |
16286 |
16287 |
11717 |
11718 |
|
Dimensions per ASME B18.2.2 1987 (1999)
|
Washers
The recommended washer for A307 bolts is an ASTM F844 USS pattern cut washer. This is an unhardened washer, typically with a larger outside diameter than a structural washer, and is used for general purposes. These washers do not have any mechanical or chemical requirements. Dimensions are typically supplied per ASME B18.21.1.
