Machinery's Handbook, 31st Edition
1706
Fasteners for Structural Applications Table 6. Dimensions of Heavy Hex Nuts for Use with Structural Bolts ANSI/ASME B18.2.6-2019
[Note (2)] A
M A M [Note (3)]
A
[Note (2)] A
H
H
F
[Note (2)]
G
Runout of Bearing Face FIM
F
G
H
Heavy Hex Nuts Specified Proof Load
Width Across Flats
Width Across Corners
Thickness
Nominal Size or Basic Product Diameter
Up to 150,000 psi
150,000 psi and Greater
Basic Max.
Min.
Max.
Min.
Basic Max. Min.
[Note (1)]
[Note (6)]
[Note (5)]
[Note (2)]
0.5000 0.6250 0.7500
0.875 0.850 1.010 1.062 1.031 1.227 1.250 1.212 1.443
0.969 1.175 1.382 1.589 1.796
0.504 0.464 0.631 0.587 0.758 0.710 0.885 0.833 1.012 0.956
0.023 0.025 0.027 0.029 0.031 0.033 0.035 0.038 0.041
0.016 0.018 0.020 0.022 0.024 0.027 0.030 0.033 0.036
1 ∕ 2 5 ∕ 8 3 ∕ 4 7 ∕ 8
7 ∕ 8
31 ∕ 64 39 ∕ 64 47 ∕ 64 55 ∕ 64 63 ∕ 64
11 ∕ 16 1 1 ∕ 4
0.8750 1 7 ∕ 16 1.438 1.394 1.660
1.625 1.575 1.876
1 1.0000
1 5 ∕ 8
1 1 ∕ 8 1.1250 1 13 ∕ 16 1.812 1.756 2.093
2.002 1 7 ∕ 64 1.139 1.079 2.209 1 7 ∕ 32 1.215 1.187 2.416 1 11 ∕ 32 1.378 1.310 2.622 1 15 ∕ 32 1.505 1.433
1 1 ∕ 4 1.2500
2 2.000 1.938 2.309
1 3 ∕ 8 1.3750 2 3 ∕ 16 2.188 2.119 2.526
1 1 ∕ 2 1.5000 2 3 ∕ 8
2.375 2.300 2.742
Note: Complete table included in B18.2.2 Square and Hex Nuts (Inch Series) (1) Unification : Only the 9 ∕
16 size is not unified dimensionally with British and Canadian standards. Unification of fine thread products is limited to sizes 1 inch and under. (2) Tops and Bearing Surfaces of Nuts : Nuts may be double chamfered or have washer faced bear ing surface and chamfered top. The diameter of chamfer circle on double chamfered nuts and diameter of washer face shall be within the limits of the maximum width across flats and 95 percent of the minimum width across flats. The tops of washer faced nuts shall be flat and the diameter of chamfer circle shall be equal to the maximum width across flats within a tolerance of − 15%. The length of chamfer at hex corners shall be 5 to 15 percent of the basic thread diameter.The surface of chamfer may be slightly convex or rounded. Bearing surfaces shall be flat and, unless otherwise specified, shall be perpendicular to the axis of the threaded hole within the total runout (FIM) tabulated for the respective nut size, type, and strength level. (3) True Position of Tapped Hole : At maximum material condition, the axis of nut body shall be located at true position with respect to the axis of the tapped hole within a tolerance zone having a diameter equivalent to 4 percent of the maximum width across flats for 1 1 ∕ 2 inch nominal size nuts or smaller. (4) Countersink : Tapped hole shall be countersunk on the bearing face or faces. The maximum countersink diameter shall be 1.08 times the thread basic (nominal) major diameter. No part of the threaded portion shall project beyond the bearing surface. (5) Corner Fill : A rounding or lack of fill at junction of hex corners with chamfer shall be permis sible provided the width across corners is within specified limits at and beyond a distance equal to 17.5% of the basic thread diameter from the chamfered faces.
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