Hex Bolt Dimensions ASME B18.2.1 Standard
What is a Hex Bolt?
A hex bolt is a type of fastener characterized by its six-sided (hexagonal) head, designed to be tightened or loosened using a wrench or socket.
Types of Hex Bolts
- Full-Thread Hex Bolt:
- Threads run the entire length of the shank, ideal for applications requiring maximum grip.
- Partial-Thread Hex Bolt:
- The upper portion of the shank is unthreaded, providing added shear strength for load-bearing connections.
- Heavy Hex Bolt:
- Features a larger and thicker head for high-strength applications like flanges and structural connections.
ASME B18.2.1
- Thread Types
- Unified coarse (UNC) and fine (UNF) thread series are included in the standard.
- Sizes
- Covers bolt and screw sizes ranging from 1/4 inch to 4 inches in diameter.
- Materials and Grades
- Materials such as carbon steel, alloy steel, and stainless steel are commonly used, with strength grades specified based on application needs.
Hex bolt Materials which we can supply
SA193/320-B7/L7, B7M/L7M, B16, B8, B8M, B8TIN STOCK 1/2″ – 1″-8UN
Inconel 625 / 2.4856, Inconel 718 / 2.4668, Alloy 825
ASTM A 453 GR 660 Class A / B / C / D
1.7709 / 21CrMoV5-7+QT (GA)
1.7225 / 42CrMo4+QT (GC)
1.4913 / X19CrMoNbVN11-1+QT (VW)
1.4923 / X22CrMoV12-1+QT (V,VH
1.4980 / X6NiCrTiMoVB25-15-2+QT (SD)
Duplex: F51 / S31803 / 1.4462
Super duplex: F53 / S32750 / 1.4410, F55 / S32760 / 1.4501
asme-b18.2.1-2010 – Square, Hex, Heavy Hex, and Askew Head Bolts and Hex, Heavy Hex, Hex Flange, Lobed Head, and Lag Screws (Inch Series)
This Standard covers the complete general and dimensional data for nine product types of inch series square and hex bolts and screws. Hex flange head and lobed head designs are new in this revision, as are screw sizes 1 5/8, 1 7/8, and 3 1/8 through 6 inches. Appendices covering gages and gaging information plus formulas on which dimensional data are based are included. Heavy hex structural bolts, formerly covered in ANSI B18.2.1, are now covered in ASME B18.2.6.
ASME-B18.2.1 Hex Bolt Dimension
|
Nominal or basic product diameter |
Unit |
Body diameter |
Width across flats (F) |
Width across corner (G) |
Head Height (H) |
Full threading length (LT) |
da (max) |
dw (min) |
D (major) 2A |
D1(pitch) 2A |
D2 (minor) MIN. 2A |
R |
c |
b |
|||||||||||||
|
inch |
inch |
UNC |
Min. |
Max. |
Min. |
Max. |
Min. |
Max. |
Min. |
Max. |
<6″(s) |
>6″(L) |
Max. |
Min. |
Min. |
Max. |
Min. |
Max. |
Min. |
Min. |
Max. |
Min. |
Max. |
Min. |
Max. |
||
|
1/2″ |
0.500 |
13 |
Inch |
0.493 |
0.500 |
0.736 |
0.750 |
0.840 |
0.866 |
0.302 |
0.323 |
1.250 |
1.500 |
0.550 |
0.675 |
0.488 |
0.499 |
0.444 |
0.449 |
0.404 |
0.015 |
0.025 |
0.015 |
0.025 |
0.000 |
0.157 |
|
|
mm |
12.52 |
12.70 |
18.69 |
19.05 |
21.34 |
22.00 |
7.67 |
8.20 |
31.75 |
38.10 |
13.97 |
17.15 |
12.39 |
12.66 |
11.26 |
11.39 |
10.26 |
0.38 |
0.64 |
0.38 |
0.64 |
0.00 |
4.00 |
||||
|
9/16″ |
0.563 |
12 |
Inch |
0.555 |
0.563 |
0.798 |
0.812 |
0.910 |
0.938 |
0.348 |
0.371 |
1.375 |
1.625 |
0.652 |
0.731 |
0.550 |
0.561 |
0.502 |
0.507 |
0.459 |
0.020 |
0.045 |
0.015 |
0.025 |
0.000 |
0.197 |
|
|
mm |
14.08 |
14.29 |
20.27 |
20.62 |
23.11 |
23.83 |
8.84 |
9.42 |
34.93 |
41.28 |
16.56 |
18.56 |
13.96 |
14.25 |
12.74 |
12.87 |
11.65 |
0.51 |
1.14 |
0.38 |
0.64 |
0.00 |
5.00 |
||||
|
5/8″ |
0.625 |
11 |
Inch |
0.617 |
0.625 |
0.922 |
0.938 |
1.051 |
1.083 |
0.378 |
0.403 |
1.500 |
1.750 |
0.715 |
0.844 |
0.611 |
0.623 |
0.559 |
0.564 |
0.512 |
0.020 |
0.045 |
0.015 |
0.025 |
0.000 |
0.197 |
|
|
mm |
15.67 |
15.88 |
23.42 |
23.83 |
26.70 |
27.51 |
9.60 |
10.24 |
38.10 |
44.45 |
18.16 |
21.44 |
15.53 |
15.83 |
14.20 |
14.34 |
13.00 |
0.51 |
1.14 |
0.38 |
0.64 |
0.00 |
5.00 |
||||
|
3/4″ |
0.750 |
10 |
Inch |
0.741 |
0.750 |
1.100 |
1.125 |
1.254 |
1.299 |
0.455 |
0.483 |
1.750 |
2.000 |
0.840 |
1.012 |
0.735 |
0.748 |
0.677 |
0.683 |
0.626 |
0.020 |
0.045 |
0.015 |
0.025 |
0.000 |
0.197 |
|
|
mm |
18.82 |
19.05 |
27.94 |
28.58 |
31.85 |
32.99 |
11.56 |
12.27 |
44.45 |
50.80 |
21.34 |
25.71 |
18.68 |
19.00 |
17.20 |
17.35 |
15.89 |
0.51 |
1.14 |
0.38 |
0.64 |
0.00 |
5.00 |
||||
|
7/8″ |
0.875 |
9 |
Inch |
0.866 |
0.875 |
1.285 |
1.312 |
1.465 |
1.516 |
0.531 |
0.563 |
2.000 |
2.250 |
1.005 |
1.181 |
0.859 |
0.873 |
0.795 |
0.801 |
0.737 |
0.040 |
0.065 |
0.015 |
0.035 |
0.000 |
0.197 |
|
|
mm |
22.00 |
22.23 |
32.64 |
33.32 |
37.21 |
38.51 |
13.49 |
14.30 |
50.80 |
57.15 |
25.53 |
29.99 |
21.82 |
22.18 |
20.18 |
20.34 |
18.71 |
1.02 |
1.65 |
0.38 |
0.89 |
0.00 |
5.00 |
||||
|
1″ |
1.000 |
8 |
Inch |
0.990 |
1.000 |
1.469 |
1.500 |
1.675 |
1.732 |
0.591 |
0.627 |
2.250 |
2.500 |
1.190 |
1.350 |
0.983 |
0.998 |
0.910 |
0.917 |
0.845 |
0.060 |
0.095 |
0.015 |
0.035 |
0.000 |
0.236 |
|
|
mm |
25.15 |
25.40 |
37.31 |
38.10 |
42.55 |
43.99 |
15.01 |
15.93 |
57.15 |
63.50 |
30.23 |
34.29 |
24.97 |
25.35 |
23.11 |
23.29 |
21.45 |
1.52 |
2.41 |
0.38 |
0.89 |
0.00 |
6.00 |
||||
|
1-1/8″ |
1.125 |
8 |
Inch |
1.114 |
1.125 |
1.631 |
1.688 |
1.859 |
1.949 |
0.658 |
0.718 |
2.500 |
2.750 |
1.315 |
1.519 |
1.079 |
1.123 |
1.035 |
1.042 |
0.970 |
0.060 |
0.095 |
0.015 |
0.035 |
0.000 |
0.236 |
|
|
mm |
28.30 |
28.58 |
41.43 |
42.88 |
47.22 |
49.50 |
16.71 |
18.24 |
63.50 |
69.85 |
33.40 |
38.59 |
27.41 |
28.52 |
26.28 |
26.46 |
24.63 |
1.52 |
2.41 |
0.38 |
0.89 |
0.00 |
6.00 |
||||
|
1-1/4″ |
1.250 |
8 |
Inch |
1.239 |
1.250 |
1.812 |
1.875 |
2.066 |
2.165 |
0.749 |
0.813 |
2.750 |
3.000 |
1.440 |
1.687 |
1.233 |
1.248 |
1.160 |
1.167 |
1.095 |
0.060 |
0.095 |
0.015 |
0.035 |
0.000 |
0.276 |
|
|
mm |
31.47 |
31.75 |
46.02 |
47.63 |
52.48 |
54.99 |
19.02 |
20.65 |
69.85 |
76.20 |
36.58 |
42.86 |
31.32 |
31.70 |
29.46 |
29.63 |
27.80 |
1.52 |
2.41 |
0.38 |
0.89 |
0.00 |
7.00 |
||||
|
1-3/8″ |
1.375 |
8 |
Inch |
1.363 |
1.375 |
1.994 |
2.062 |
2.273 |
2.382 |
0.810 |
0.878 |
3.000 |
3.250 |
1.565 |
1.856 |
1.358 |
1.373 |
1.284 |
1.292 |
1.219 |
0.060 |
0.095 |
0.015 |
0.035 |
0.000 |
0.276 |
|
|
mm |
34.62 |
34.93 |
50.65 |
52.37 |
57.73 |
60.50 |
20.57 |
22.30 |
76.20 |
82.55 |
39.75 |
47.13 |
34.49 |
34.87 |
32.62 |
32.81 |
30.97 |
1.52 |
2.41 |
0.38 |
0.89 |
0.00 |
7.00 |
||||
|
1-1/2″ |
1.500 |
8 |
Inch |
1.488 |
1.500 |
2.175 |
2.250 |
2.480 |
2.598 |
0.902 |
0.974 |
3.250 |
3.500 |
1.690 |
2.025 |
1.483 |
1.498 |
1.409 |
1.417 |
1.344 |
0.060 |
0.095 |
0.015 |
0.035 |
0.000 |
0.315 |
|
|
mm |
37.80 |
38.10 |
55.25 |
57.15 |
62.99 |
65.99 |
22.91 |
24.74 |
82.55 |
88.90 |
42.93 |
51.44 |
37.66 |
38.04 |
35.80 |
35.98 |
34.15 |
1.52 |
2.41 |
0.38 |
0.89 |
0.00 |
8.00 |
||||
|
1-5/8″ |
1.625 |
8 |
Inch |
1.613 |
1.625 |
2.356 |
2.438 |
2.686 |
2.815 |
0.962 |
1.038 |
3.500 |
3.750 |
1.795 |
2.194 |
1.608 |
1.623 |
1.534 |
1.542 |
1.469 |
0.060 |
0.095 |
0.015 |
0.035 |
0.000 |
0.354 |
|
|
mm |
40.97 |
41.28 |
59.84 |
61.93 |
68.22 |
71.50 |
24.43 |
26.37 |
88.90 |
95.25 |
45.60 |
55.73 |
40.84 |
41.22 |
38.97 |
39.16 |
37.32 |
1.52 |
2.41 |
0.38 |
0.89 |
0.00 |
9.00 |
||||
|
1-3/4″ |
1.750 |
8 |
Inch |
1.738 |
1.750 |
2.538 |
2.625 |
2.893 |
3.031 |
1.054 |
1.134 |
3.750 |
4.000 |
1.940 |
2.362 |
1.733 |
1.748 |
1.659 |
1.667 |
1.594 |
0.060 |
0.095 |
0.015 |
0.035 |
0.000 |
0.354 |
|
|
mm |
44.15 |
44.45 |
64.47 |
66.68 |
73.48 |
76.99 |
26.77 |
28.80 |
95.25 |
101.60 |
49.28 |
60.00 |
44.01 |
44.39 |
42.14 |
42.33 |
40.50 |
1.52 |
2.41 |
0.38 |
0.89 |
0.00 |
9.00 |
||||
|
1-7/8″ |
1.875 |
8 |
Inch |
1.863 |
1.875 |
2.719 |
2.812 |
3.099 |
3.248 |
1.114 |
1.198 |
4.000 |
4.250 |
2.071 |
2.531 |
1.858 |
1.873 |
1.784 |
1.792 |
1.719 |
0.060 |
0.095 |
0.015 |
0.035 |
0.000 |
0.394 |
|
|
mm |
47.32 |
47.63 |
69.06 |
71.42 |
78.71 |
82.50 |
28.30 |
30.43 |
101.60 |
107.95 |
52.60 |
64.28 |
47.19 |
47.57 |
45.31 |
45.50 |
43.67 |
1.52 |
2.41 |
0.38 |
0.89 |
0.00 |
10.00 |
||||
|
2″ |
2.000 |
8 |
Inch |
1.988 |
2.000 |
2.900 |
3.000 |
3.306 |
3.464 |
1.175 |
1.263 |
4.250 |
4.500 |
2.190 |
2.688 |
1.983 |
1.998 |
1.909 |
1.917 |
1.844 |
0.060 |
0.095 |
0.015 |
0.035 |
0.000 |
0.394 |
|
|
mm |
50.50 |
50.80 |
73.66 |
76.20 |
83.97 |
87.99 |
29.85 |
32.08 |
107.95 |
114.30 |
55.63 |
68.28 |
50.36 |
50.74 |
48.48 |
48.68 |
46.85 |
1.52 |
2.41 |
0.38 |
0.89 |
0.00 |
10.00 |
||||
|
2-1/4″ |
2.250 |
8 |
Inch |
2.238 |
2.250 |
3.262 |
3.375 |
3.719 |
3.897 |
1.327 |
1.423 |
– |
5.000 |
2.440 |
3.037 |
2.233 |
2.248 |
2.158 |
2.166 |
2.094 |
0.060 |
0.095 |
0.015 |
0.035 |
0.000 |
0.433 |
|
|
mm |
56.85 |
57.15 |
82.85 |
85.73 |
94.46 |
98.98 |
33.71 |
36.14 |
– |
127.00 |
61.98 |
77.15 |
56.71 |
57.09 |
54.82 |
55.03 |
53.19 |
1.52 |
2.41 |
0.38 |
0.89 |
0.00 |
11.00 |
||||
|
2-1/2″ |
2.500 |
8 |
Inch |
2.488 |
2.500 |
3.625 |
3.750 |
4.133 |
4.330 |
1.479 |
1.583 |
– |
5.500 |
2.690 |
3.375 |
2.483 |
2.498 |
2.408 |
2.416 |
2.344 |
0.060 |
0.095 |
0.015 |
0.035 |
0.000 |
0.472 |
|
|
mm |
63.20 |
63.50 |
92.08 |
95.25 |
104.98 |
109.98 |
37.57 |
40.21 |
– |
139.70 |
68.33 |
85.73 |
63.06 |
63.44 |
61.17 |
61.37 |
59.54 |
1.52 |
2.41 |
0.38 |
0.89 |
0.00 |
12.00 |
||||
|
2-3/4″ |
2.750 |
8 |
Inch |
2.738 |
2.750 |
3.988 |
4.125 |
4.546 |
4.763 |
1.632 |
1.744 |
– |
6.000 |
2.940 |
3.712 |
2.733 |
2.748 |
2.658 |
2.666 |
2.594 |
0.060 |
0.095 |
0.015 |
0.035 |
0.000 |
0.512 |
|
|
mm |
69.55 |
69.85 |
101.30 |
104.78 |
115.47 |
120.98 |
41.45 |
44.30 |
– |
152.40 |
74.68 |
94.28 |
69.41 |
69.79 |
67.51 |
67.72 |
65.89 |
1.52 |
2.41 |
0.38 |
0.89 |
0.00 |
13.00 |
||||
|
3″ |
3.000 |
8 |
Inch |
2.988 |
3.000 |
4.350 |
4.500 |
4.959 |
5.196 |
1.815 |
1.935 |
– |
6.500 |
3.190 |
3.712 |
2.982 |
2.997 |
2.908 |
2.916 |
2.844 |
0.060 |
0.095 |
0.015 |
0.035 |
0.000 |
0.591 |
|
|
mm |
75.90 |
76.20 |
110.49 |
114.30 |
125.96 |
131.98 |
46.10 |
49.15 |
– |
165.10 |
81.03 |
94.29 |
75.75 |
76.13 |
73.86 |
74.07 |
72.24 |
1.52 |
2.41 |
0.38 |
0.89 |
0.00 |
15.00 |
||||
