Heavy hex jam nuts appear thinner compared to standard heavy hex nuts; but, they have the same dimension, particularly across the flats and corners. Heavy hex jam nuts have two common applications. A heavy hex jam nut can be threaded onto a bolt and run tightly against a standard nut. Well, this phenomenon helps lock the nut in its place apart from preventing it from pulling back. Moreover, these nuts are used for leveling purposes. Since hot-dip galvanizing tends to add 2.2 – 5 mils thickness to the threaded portion of a fastener, our galvanized heavy hex square nuts usually get tapped oversize in order to balance the corrosion resistant coating of the bolts.

Dimensions

Click table to show drawing

Nominal Size	F			C		H			Part Numbers
	Width Across Flats			Width Across Corners		Thickness
	Basic	Max	Min	Max	Min	Basic	Max	Min	Plain	Galvanized
3⁄8	11⁄16	0.688	0.669	0.794	0.763	15⁄64	0.252	0.216	–	–
1⁄2	7⁄8	0.875	0.850	1.010	0.969	19⁄64	0.317	0.277	–	–
5⁄8	11⁄16	1.062	1.031	1.227	1.175	23⁄64	0.381	0.337	–	–
3⁄4	11⁄4	1.250	1.212	1.443	1.382	27⁄64	0.446	0.398	–	18404
7⁄8	17⁄16	1.438	1.394	1.660	1.589	31⁄64	0.510	0.458	–	–
1	15⁄8	1.625	1.575	1.876	1.796	35⁄64	0.575	0.519	17112	17113
11⁄8	113⁄16	1.812	1.756	2.093	2.002	39⁄64	0.639	0.579	–	–
11⁄4	2	2.000	1.938	2.309	2.209	23⁄32	0.751	0.687	17114	17115
13⁄8	213⁄16	2.188	2.119	2.526	2.416	25⁄32	0.815	0.747	–	–
11⁄2	23⁄8	2.375	2.300	2.742	2.622	27⁄32	0.880	0.808	17116	17117
15⁄8	29⁄16	2.562	2.481	2.959	2.828	29⁄32	0.944	0.868	–	–
13⁄4	23⁄4	2.750	2.662	3.175	3.035	31⁄32	1.009	0.929	17118	17119
17⁄8	215⁄16	2.938	2.844	3.392	3.242	11⁄32	1.073	0.989	–	–
2	31⁄8	3.125	3.025	3.608	3.449	13⁄32	1.138	1.050	17120	17121
21⁄4	31⁄2	3.500	3.388	4.041	3.862	113⁄64	1.251	1.155	19847	19846
21⁄2	37⁄8	3.875	3.750	4.474	4.275	129⁄64	1.505	1.401	–	–
23⁄4	41⁄4	4.250	4.112	4.907	4.688	137⁄64	1.634	1.522	–	–
3	45⁄8	4.625	4.475	5.340	5.102	145⁄64	1.763	1.643	–	–
31⁄4	5	5.000	4.838	5.774	5.515	113⁄16	1.876	1.748	–	–
31⁄2	53⁄8	5.375	5.200	6.207	5.928	115⁄16	2.006	1.870	–	–
33⁄4	53⁄4	5.750	5.562	6.640	6.341	21⁄16	2.134	1.990	–	–
4	61⁄8	6.125	5.925	7.073	6.755	23⁄16	2.264	2.112	–	–
Dimensions per ASME B18.2.2 1987 (R 1999)