Inconel 718 Heavy Hex Nuts to ASME B18.2.6 Heavy Hex Nuts For Use With Structural Bolts
ASME B18.2.6 Heavy Hex Nuts For Use With Structural Bolts Dimensions
| Nominal Size or Basic Major Diameter of Thread [Note (1)] |
Width Across Flats, F [Note (2)] |
Width Across Corners, G [Note (3)] |
Thickness, H [Note (4)] |
Total Runout of Bearing Face FIM, Heavy Hex Nuts, Specified Proof Load [Note (5)] |
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|---|---|---|---|---|---|---|---|---|---|---|---|
| Nominal | Max. | Min. | Max. | Min. | Nominal | Max. | Min. |
<150,000 psi |
≥150,000 psi |
||
| ½ | 0.500 | ⅞ | 0.875 | 0.850 | 1.010 | 0.969 | 31⁄64 | 0.504 | 0.464 | 0.023 | 0.016 |
| ⅝ | 0.718 | 1⅙ | 1.062 | 1.031 | 1.227 | 1.175 | 39⁄64 | 0.631 | 0.587 | 0.025 | 0.018 |
| ¾ | 0.750 | 1¼ | 1.250 | 1.212 | 1.443 | 1.382 | 47⁄64 | 0.758 | 0.710 | 0.027 | 0.020 |
| ⅞ | 0.875 | 1⅙ | 1.438 | 1.394 | 1.660 | 1.589 | 55⁄64 | 0.885 | 0.833 | 0.029 | 0.022 |
| 1 | 1.000 | 1⅝ | 1.718 | 1.575 | 1.876 | 1.796 | 63⁄64 | 1.012 | 0.956 | 0.031 | 0.024 |
| 1⅛ | 1.125 | 1 13⁄16 | 1.812 | 1.756 | 2.093 | 2.002 | 1 7⁄64 | 1.139 | 1.079 | 0.033 | 0.027 |
| 1¼ | 1.250 | 2 | 2.000 | 1.938 | 2.309 | 2.209 | 1 7⁄32 | 1.251 | 1.187 | 0.035 | 0.030 |
| 1⅜ | 1.375 | 2 3⁄16 | 2.188 | 2.119 | 2.526 | 2.416 | 1 11⁄32 | 1.378 | 1.310 | 0.038 | 0.033 |
| 1½ | 1.500 | 2⅜ | 2.375 | 2.300 | 2.742 | 2.622 | 1 15⁄32 | 1.505 | 1.433 | 0.041 | 0.036 |
GENERAL NOTE: See additional requirements in section 3. Complete table included in ASME B18.2.2.
NOTES:
(1) See para. 2.4.1.
(2) See para. 3.1.1.
(3) See para. 3.1.4.
(4) See para. 3.1.2.
(5) See para. 3.1.3.
ASME B18.
Maximum width across flats shall not be exceeded (except as stated in the previous paragraph). No transverse section through the nut between 25% and 75% of the actual nut thickness, as measured from the bearing surface, shall be less than the minimum width across flats.
Nut DimensionsNuts shall conform to the dimensions given in Table 3.1-1. Heavy hex nut formulas for thickness, width across flats, and width across corners are given in ASME B18.2.2, Nonmandatory Appendix A.
- Width Across Flats. The width across flats of heavy hex nuts shall be the overall distance measured, perpendicular to the axis of the nut, between two opposite sides of the nut in accordance with Table 3.1-1. For milled-from-bar hex nuts, the nominal bar size used shall be the closest commercially available size to the specified basic width across flats of the nut. If the bar dimensions will not conform to the dimensions in Table 3.1-1, the manufacturers must obtain approval from the purchaser prior to manufacturing.
- Nut Thickness. The nut thickness shall be the overall distance measured parallel to the axis of the nut, from the top of the nut to the bearing surface, and shall include the thickness of the washer face where provided.
- Tops and Bearing Surfaces.
Nuts may be double chamfered or have a washer faced bearing 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% 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% 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. - Corner Fill. A rounding or lack of fill at junction of hex corners with chamfer shall be permissible, 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.
- Position of Hexagon to Tapped Hole. At maximum material condition, the nut body shall be located at true position with respect to the thread pitch diameter within a tolerance zone having a diameter equivalent to 4% of the maximum width across flats for 11∕2 in. nominal size nuts or smaller.
- 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.
- Threads. Threads shall be Class 2B in accordance with ASME B1.1.
- Thread Gaging. Unless otherwise specified by the purchaser, gaging for screw thread dimensional acceptability shall be in accordance with Gaging System 21 as specified in ASME B1.3.
- Overtapping. When nuts are hot-dip or mechanically deposited zinc-coated, they shall be overtapped or tapped after coating in accordance with the provisions of ASTM A563.