HEX COUPLING NUT DIMENSIONS TABLE


Hex coupling nut dimensions sizes table according to ASME B18.2.2. All dimensions are given in inches. Width across flats (wrench size) and corners and hex coupling nut thickness are given for nut sizes up to 6 inches.

Hex Coupling Nut Dimensions

Note 1: Nuts shall be furnished without a hole, unless specially ordered by the purchaser. In some applications it may be desirable to assure that the threaded parts joined by a coupling nut are each engaged to approximately one-half nut thickness. As a visual inspection aid, a hole drilled through one side of the nut is recommended. The hole should be located at mid-nut thickness, and have a diameter of 0.2 to 0.4 times nominal nut size for sizes 2 1⁄2 in. and smaller, and 1 in. for sizes 2 3⁄4 in. and larger.


Nominal
 Size
Basic
Major
Diameter
of
Thread 
F G H
Width
Across
Flats
Width
Across
Corners
Thickness
Hex
Nut
basic min max. min. max. basic min. max.
#6 0.138 5/16 0.302 0.312 0.344 0.361 1/2 0.470 0.510
#8 0.164 5/16 0.302 0.312 0.344 0.361 5/8 0.595 0.645
#10 0.190 5/16 0.302 0.312 0.344 0.361 3/4 0.711 0.760
1/4 0.250 7/16 0.428 0.438 0.488 0.505 1 3/4 1.690 1.760
5/16 0.312 1/2 0.489 0.500 0.557 0.577 1 3/4 1.690 1.760
3/8 0.375 9/16 0.551 0.562 0.628 0.650 1 3/4 1.690 1.760
7/16 0.437 5/8 0.607 0.625 0.692 0.722 1 3/4 1.690 1.760
1/2 0.500 11/16 0.663 0.688 0.756 0.794 1 3/4 1.690 1.760
9/16 0.562 13/16 0.782 0.813 0.891 0.939 2 1/8 2.067 2.135
5/8 0.625 13/16 0.782 0.813 0.891 0.939 2 1/8 2.067 2.135
3/4 0.750 1 0.963 1.000 1.097 1.155 2 1/4 2.190 2.260
7/8 0.875 1 1/4 1.212 1.250 1.382 1.443 2 1/2 2.440 2.510
1 1.000 1 3/8 1.325 1.375 1.511 1.588 2 3/4 2.690 2.760
Nominal
 Size
Basic
Major
Diameter
of
Thread 
F G H
Width
Across
Flats
Width
Across
Corners
Thickness
Hex
Nut
basic min max. min. max. basic min. max.
1 1/8 1.125 1 1/2 1.450 1.500 1.653 1.732 3 2.940 3.010
1 1/4 1.250  1 5/8 1.575 1.625 1.825 1.876 3 2.940 3.010
1 1/2 1.500 2 1.950 2.000 2.275 2.309 3 1/2 3.440 3.510
1 5/8 1.625 2 9/16 2.481 2.562 2.828 2.959 4 7/8 4.830 4.910
1 3/4 1.750 2 3/4 2.662 2.750 3.035 3.175 5 1/4 5.210 5.290
1 7/8 1.875 2 15/16 2.844 2.938 3.242 3.392 5 5/8 5.580 5.670
2 2.000 3 1/8 3.025 3.125 3.448 3.608 6 5.950 6.040
2 1/4 2.250 3 1/2 3.388 3.500 3.862 4.041 6 3/4 6.700 6.800
2 1/2 2.500 3 7/8 3.750 3.875 4.275 4.474 7 1/2 7.440 7.550
2 3/4 2.750 4 1/4 4.112 4.250 4.688 4.907 8 1/4 8.190 8.310
3 3.000 4.5/8 4.475 4.625 5.101 5.340 9 8.940 9.060
Nominal
 Size
Basic
Major
Diameter
of
Thread 
F G H
Width
Across
Flats
Width
Across
Corners
Thickness
Hex
Nut
basic min max. min. max. basic min. max.
3 1/4 3.250 5 4.838 5.000 5.515 5.773 9 3/4 9.680 9.810
3 1/2 3.500 5 3/8 5.200 5.375 5.928 6.206 10 1/2 10.430 10.570
3 3/4 3.750 5 3/4 5.562 5.750 6.340 6.639 11 1/4 11.170 11.320
4 4.000 6 1/8 5.925 6.125 6.754 7.072 12 11.920 12.080
4 1/4 4.250 6 1/2 6.288 6.500 7.168 7.506 12 3/4 12.670 12.830
4 1/2 4.500 6 7/8 6.650 6.875 7.581 7.939 13 1/2 13.420 13.580
4 3/4 4.750 7 1/4 7.012 7.250 7.994 8.372 14 1/4 14.160 14.340
5 5.000 7 5/8 7.375 7.625 8.408 8.805 15 14.910 15.090
5 1/4 5.250 8 7.738 8.000 8.821 9.238 15 3/4 15.650 15.850
5 1/2 5.500 8 3/8 8.100 8.375 9.234 9.671 16 1/2 16.400 16.600
5 3/4 5.750 8 3/4 8.462 8.750 9.647 10.104 17 1/4 17.150 17.350
6 6.000 9 1/8 8.825 9.125 10.060 10.537 18 17.890 18.110


Reference:

  • ASME B18.2.2-2010, Square and Hex Nuts (Inch Series)