Torque Techinacal Information
A guide to specifying
torque values for fasteners continued...

TABLE 6 -- 10  BOLT INFORMATION

TABLE 6 BRITISH STANDARD FINE, BSF

Nominal Bolt Size in TPI Nominal Hex A/F Size in Nominal Stress Area in2

1/4
5/16
3/8
7/16
1/2
*9/16
5/8
3/4
7/8
1
1 1/8
1 1/4
1 3/8
1 1/2

26
22
20
18
16
16
14
12
11
10
9
9
8
8

.445
.525
.600
.710
.820
.920
1.010
1.200
1.300
1.480
1.670
1.860
2.050
2.220

0.0357
0.9568
0.084
0.1159
0.152
0.1983
0.2432
0.3525
0.4873
0.6418
0.8145
1.0267
1.237
1.496


Derived from Information taken from BS84: 1956 & BS.1083: 1965

TABLE 7 BRITISH STANDARD - WHITWORTH, BSW

Nominal Bolt Size in TPI Nominal Hex A/F (BS1093 & BS916 Obsolete) in Nominal Hex A/F Whitworth Large BS190 Obsolete See Note Nominal Stress Area in2

1/8
3/16
1/4
5/16
3/8
7/16
1/2
*9/16
5/8
3/4
7/8
1
1 1/8
1 1/4
1 3/8
1 1/2

40
24
20
18
16
14
12
12
11
10
9
8
7
7
6
6

-
.338
.445
.525
.600
.710
.820
.920
1.010
1.200
1.300
1.480
1.670
1.860
2.050
2.220

.338
.445
.525
.600
.710
.820
.920
1.010
1.200
1.300
1.480
1.670
1.860
2.050
2.220
2.410

0.008
0.017
0.032
0.0527
0.0779
0.1069
0.1385
0.183
0.227
0.336
0.464
0.608
0.766
0.972
1.159
1.410


Derived from information taken from BS84: 1956 & BS1083: 1965

TABLE 8 UNIFIED FINE THREAD SERIES, UNF
Normal Bolt Size in TPI Nominal Hex A/F Size in Nominal Stress Area in2

1/4
5/16
3/8
7/16

1/2
*9/16

5/8
3/4
7/8
1
1 1/8
1 1/4
1 3/8
1 1/2

28
24
24
20

20
18

18
16
14
12
12
12
12
12

.4375
.5000
.5625
Bolts   Nuts
.6250   .6850
.7500
Bolts   Nuts
.8125   .8750
.9375
1.1250
1.3125
1.5000
1.6875
1.8750
2.0625
2.2500

0.0368
0.0587
0.0886
0.1198

0.1612
0.205

0.258
0.375
0.513
0.667
0.861
1.078
1.321
1.588


Derived from Information taken from BS1768: 1963 & BS.1580: 1962

TABLE 9 UNIFIED COARSE THREAD SERIES, UNC

Normal Bolt Size in TPI Nominal Hex A/F Size in Nominal Stress Area in2

1/4
5/16
3/8
7/16

1/2
*9/16

5/8
3/4
7/8
1
1 1/8
1 1/4
1 3/8
1 1/2

20
18
16
4

13
12

11
10
9
8
7
7
6
6

.4375
.5000
.5625
Bolts   Nuts
.6250   .6850
.7500
Bolts   Nuts
.8125   .8750
.9375
1.1250
1.3125
1.5000
1.6875
1.8750
2.0625
2.2500

0.0324
0.0532
0.0786
0.1078

0.1438
0.184

0.229
0.338
0.467
0.612
0.771
0.978
1.166
1.418


Derived from information taken from BS1768: 1963 & BS1580: 1962


TABLE 10 B.A (BRITISH ASSOCIATION)

BA NO. Nominal Bolt/Screw Dia in Pitch mm TPI Ref Only Nom' Hex A/F Size Nom' Stress Area in2

0
1
*2
3
*4
5
6
7
8
9
10

0.2362
0.2087
0.185
0.1614
0.1417
0.1260
0.1102
0.0984
0.0866
0.0748
0.0669

1.00
0.90
0.81
0.73
0.66
0.59
0.53
0.48
0.43
0.39
0.35

25.400
28.2222
31.3580
34.7945
38.849
43.0508
47.9245
52.9167
59.0698
65.1282
72.5714

0.413
0.365
0.324
0.282
0.248
0.220
0.193
0.172
0.152
0.131
0.117

0.0317
0.0245
0.0192
0.0144
0.0110
0.0087
0.0065
0.0052
0.00399
0.00292
0.00234


* Preferred sizes for hex headed bolts and screws
2, 4, 6, 8, 10 BA preferred sizes for hex nuts
Derived from information taken from BS57: 1951(obsolete) BS93: 1951
(obsolete) & BS3580: 1964


British Standard Sizes
Whitworth
The bolt diameters given under the headings "Whitworth' refer to the original large hexagons for bolts and nuts as specified in BS.28 and BS.190.
The table above gives details of Whitworth thread diameters given in BS.28 and BS.190 compared with thread diameters given in BS.916 and BS.1083 which have smaller (S.B.) hexagon heads and nut dimensions for the same size Whitworth thread diameter.
The specifications for Whitworth bolts and nuts according to BS.916 and BS.1083 are identical with B.S.F. which have not been altered.
A typical example would therefore show:-
Hexagon 820 in across flats = 7/16 in Whitworth thread dia. (BS.190) or 1/2 in Whitworth (BS) and 1/2 in B.S.F. (BS.1083 and 916)
The British standards quoted above are listed as follows:
BS*28 Black Hexagon bolts and nuts-
Whitworth form thread (Withdrawn)
BS.190 Bright Hexagon bolts and nuts-
Whitworth form thread (Withdrawn)
BS.196 Black Hexagon bolts and nuts-
Whitworth form thread (Obsolescent)
BS.1083 Precision Hexagon bolts and nuts - Whitworth form thread
(Obsolescent)
British "Whitworth" Hexagon Range
If in doubt always quote the actual caross flats dimension