Heavy Hex Nut Size Table Chart per. ASME B18.2.2

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Heavy Hex Nut dimensions per ASME B18.2.2 1987 (1999).

Heavy Hex Nut Width Across Flats

The width across flats of nut shall be the distance measured, perpendicular to the axis of nut, overall be tween two opposite sides of the nut in accordance with the notes on respective dimensional tables. For milled- from-bar hex nuts, he nominal bar size used shall be the closest commercially available size to the specified basic width across flats of the nut. For milled-from- bar nonferrous nuts, the tabulated maximum (basic) width screws flats dimensions may be exceeded to con- form with the commercial tolerances of drawn or rolled bar stock material.

Nut Thickness

The nut thickness shall be the overall distance, measured parallel to the axis of nut, from the top of the nut to the bearing surface and shall include the thick- ness of the washer face where provided

Threads shall be Unified Standard, Class 2B, of the series specified in the notes on respective dimensional tables, in accordance with Unified Inch Screw Threads (UN and UNR Thread Form), ANSI B1. l.

All dimensional data given in inch units

Nominal Thread Size	F			C		H			Approximate Weight Per Nut
	Width Across Flats			Width Across Corners		Thickness
	Basic	Max	Min	Max	Min	Basic	Max	Min
3/8	11/16	0.688	0.669	0.794	0.763	23/64	0.377	0.341	0.03
1/2	7/8	0.875	0.850	1.010	0.969	31/64	0.504	0.464	0.07
5/8	1-1/16	1.062	1.031	1.227	1.175	39/64	0.631	0.587	0.12
3/4	1-1/4	1.250	1.212	1.443	1.382	47/64	0.758	0.710	0.20
7/8	1-7/16	1.438	1.394	1.660	1.589	55/64	0.885	0.833	0.30
1	1-5/8	1.625	1.575	1.876	1.796	63/64	1.012	0.956	0.43
1-1/8	1-13/16	1.812	1.756	2.093	2.002	1-7/64	1.139	1.079	0.59
1-1/4	2	2.000	1.938	2.309	2.209	1-7/32	1.251	1.187	0.79
1-3/8	2-3/16	2.188	2.119	2.526	2.416	1-11/32	1.378	1.310	1.02
1-1/2	2-3/8	2.375	2.300	2.742	2.622	1-15/32	1.505	1.433	1.31
1-5/8	2-9/16	2.562	2.481	2.959	2.828	1-19/32	1.632	1.556	1.62
1-3/4	2-3/4	2.750	2.662	3.175	3.035	1-23/32	1.759	1.679	2.04
1-7/8	2-15/16	2.938	2.844	3.392	3.242	1-27/32	1.886	1.802	2.41
2	3-1/8	3.125	3.025	3.608	3.449	1-31/32	2.013	1.925	2.99
2-1/4	3-1/2	3.500	3.388	4.041	3.862	2-13/64	2.251	2.155	4.19
2-1/2	3-7/8	3.875	3.750	4.474	4.275	2-29/64	2.505	2.401	5.64
2-3/4	4-1/4	4.250	4.112	4.907	4.688	2-45/64	2.759	2.647	7.38
3	4-5/8	4.625	4.475	5.340	5.102	2-61/64	3.013	2.893	9.50
3-1/4	5	5.000	4.838	5.774	5.515	3-3/16	3.252	3.124	11.94
3-1/2	5-3/8	5.375	5.200	6.207	5.928	3-7/16	3.506	3.370	15.26
3-3/4	5-3/4	5.750	5.562	6.640	6.341	3-11/16	3.760	3.616	18.12
4	6-1/8	6.125	5.925	7.073	6.755	3-15/16	4.014	3.862	21.80

 

Basic Thread Diameter	F Flat Width	H Thickness
.25	0.500	0.234
.5	0.875	0.484
.5625	0.938	0.547
.625	1.062	0.609
.75	1.250	0.734
.875	1.438	0.859
1	1.625	0.984
1.125	1.812	1.109
1.25	2.000	1.219
1.375	2.188	1.343
1.5	2.375	1.469
1.625	5.620	1.594
1.75	2.750	1.719
1.875	2.938	1.844
2	3.125	1.969
2.25	3.500	2.203
2.5	3.875	2.453
2.75	4.250	2.703
3	4.625	2.953
3.25	5.000	3.188
3.5	5.375	3.438
3.75	5.750	3.688
4	6.125	3.938

GENERAL NOTES: SQUARE AND HEX NUTS (INCH SERIES)

• Unification. Bold type indicates products unified dimensionally with British and Cana- dian standards. Unification of fine thread nuts is limited to sizes l in. and smaller.
• True Position of Tapped Hole. The axis of tapped hole shall be located at true position with respect to the axis of nut body within a tolerance zone having a diameter equiva- lent to 4% of the maximum width across flats, regardless of feature size.
• Countersink. Tapped hole shall be countersunk on the bearing face or faces. The maximum countersink diameter shall be the thread basic (nominal) major diameter plus 0.030 in. for 3/8 in. nominal size nuts and smaller, and 1 .O8 times the basic major diameter for nuts larger than 3/8 in. No part of the threaded portion shall project be- yond the bearing surface.
• Threads. Threads shall be unified coarse, fine, or 8 thread series (UNC, UNF or 8 UN series), Class 28.
• Material. Unless otherwise specified, chemical and mechanical properties of steel nuts shall conform with Grade A of ASTM A 563, Carbon and Alloy Steel Nuts; or Grade 2 of SAE J995, Mechanical and Material Requirements for Steel Nuts. Nuts of other materials such as corrosion resistant (stainless) steel, brass, bronze, and alumi- num alloys shall have properties as agreed upon between the manufacturer and pur- chaser. The properties for nuts of several grades of corrosion resistant steel alloys are covered in ASTM F 594, and of several nonferrous materials in the ASTM F 467. .

NOTES:

• Width Across Flats. Maximum width across flats shall not be exceeded (see excep- tion in General Data). No transverse action 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. For milled-from-bar nuts, see statement in General Data pertaining to the nominal bar size to be used.
• 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 a? and beyond a distance equal to 17.5% of the basic thread diameter from the chamfered faces.
• Tops and Bearing Surfaces of Nuts. Nuts in sizes 5/.. in. nominal size and smaller shall be double chamfered. Larger size nuts shall be double chamfered or have 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 mini- mum 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 from 5% to 1 5% of the basic thread diameter. The surface of chamfer may be slightly convex or rounded. Bearing surfaces shall be flat and perpendicular to the axis of the threaded hole within the FIM limits specified for the respective nut type and strength level..