Bsi bs 4a 112 1992 (1999)

BRITISH STANDARD

BS 4A 112:
1992

(superseding
BS 3A 112:1985)

Specification for

Cadmium-plated steel
shear bolts
(Unified hexagons and
Unified threads)


BS 4A 112:1992

Committees responsible for this
British Standard
The preparation of this British Standard was entrusted by the Aerospace
Standards Policy Committee (ACE/-) to Technical Committee ACE/12, upon
which the following bodies were represented:
The Association of Electronics, Telecommunications and Business Equipment
Industries
British Industrial Fasteners Federation
Ministry of Defence
Society of British Aerospace Companies Ltd.

This British Standard, having
been prepared under the

direction of the Aerospace
Standards Policy Committee,
was published under the
authority of the Standards
Board and comes into effect on
15 December 1992
© BSI 08-1999
The following BSI references
relate to the work on this
standard:
Committee reference ACE/12
Draft for information 92/80172

ISBN 0 580 21346 3

Amendments issued since publication
Amd. No.

Date

Comments


BS 4A 112:1992

Contents
Page
Committees responsible
Inside front cover
Foreword

ii
1
Scope
1
2
References
1
3
Procurement
1
4
Materials and manufacture
1
5
Mechanical properties for forged bolts in the finally
heat-treated condition
1
6
Anti-corrosion treatment
1
7
Dimensions
1
8
Screw threads
1
Table 1 — Dimensions
2
Table 2 — Bearing length L, clamping length M and overall length E
3

List of references
Inside back cover

© BSI 08-1999

i


BS 4A 112:1992

Foreword
This edition of this British Standard has been prepared under the direction of the
Aerospace Standards Policy Committee and supersedes BS 3A 112:1985 which is
withdrawn.
This edition clarifies the maximum diameter of bolts after plating, but it does not
reflect a full review or revision of the standard, which will be undertaken in due
course. The 0.0003 in plating allowance on the maximum diameter quoted
in BS 3A 112 (and preceding editions) is now embodied in the maximum diameter
after plating in Table 1, and separate reference to a plating allowance has been
deleted. The maximum diameter of bolts before plating has been deleted and the
thickness of plating is now controlled.
An equivalent range of bolts with unplated shanks is specified in BS 3A 109. Nuts
suitable for use with either range of shear bolts are specified in BS 2A 110.
A British Standard does not purport to include all the necessary provisions of a
contract. Users of British Standards are responsible for their correct application.

Compliance with a British Standard does not of itself confer immunity
from legal obligations.

Summary of pages

This document comprises a front cover, an inside front cover, pages i and ii,
pages 1 to 8, an inside back cover and a back cover.
This standard has been updated (see copyright date) and may have had
amendments incorporated. This will be indicated in the amendment table on the
inside front cover.
ii

© BSI 08-1999


BS 4A 112:1992

1 Scope

This British Standard specifies materials,
dimensions, finish and inspection requirements for
steel shear bolts with Unified hexagons and Unified
threads and with close tolerance shanks, cadmium
plated, to be suitable for insertion in aluminium
alloy materials for aerospace use.
NOTE The latest revision of an Aerospace Series standard is
indicated by a prefix number.

2 References

2.1 Normative references

This British Standard incorporates, by reference,
provisions from specific editions of other

publications. These normative references are cited
at the appropriate points in the text and the
publications are listed on the inside back cover.
Subsequent amendments to, or revisions of, any of
these publications apply to this standard only when
incorporated in it by updating or revision.

2.2 Informative references

This British Standard refers to other publications
that provide information or guidance. Editions of
these publications current at the time of issue of this
standard are listed on the inside back cover, but
reference should be made to the latest editions.

3 Procurement

The bolts shall conform to the latest edition of
BS A 100.

4 Materials and manufacture

The bolts shall be manufactured by one of the
following methods:
a) machined from bright drawn bars which
conform to BS S 154:1976;
NOTE S 96 material may be used until stocks are
exhausted.

b) forged from material which conforms to one of

the following British Standards:
BS 2S 147:1976
BS 2S 149:1976
BS S 158:1977

© BSI 08-1999

5 Mechanical properties for forged
bolts in the finally heat-treated
condition

Forged bolts in the finally heat-treated condition
shall have the following mechanical properties:
a) 0.2 per cent proof stress: not less
than 690 MPa:
b) tensile strength: 880 MPa to 1 080 MPa;
c) elongation on 5.65 Ỉ So (area): not less
than 12 %;
d) impact value: not less than 55 J.

6 Anti-corrosion treatment

All finished bolts shall be coated with cadmium in
accordance with DEF STAN 03-19[1].

7 Dimensions

7.1 All finished bolts, after the application of the

anti-corrosion coating, shall be in accordance with

the dimensions and tolerances given in Table 1
and Table 2.
7.2 The clamping length M of the bolts shall be in
accordance with the dimensions and tolerances
in Table 2 and shall be such that, when a standard
nut without countersink or a ring gauge without
countersink has been screwed on as far as possible
by hand, its leading face is within the distance M
from the underside of the bolt head. The runout of
the thread shall not exceed twice the pitch.
7.3 The nominal length of the bolt shall be the
minimum bearing length L, which is determined by
the minimum clamping length M less two thread
pitches.

8 Screw threads

The bolts shall have Unified threads of the form and
class of fit specified in the latest edition of BS A 100.

1


2
0.2500
0.3125
0.3750
0.4375
0.5000
0.5625

0.6250
0.7500

min.

0.2493
0.3118
0.3743
0.4368
0.4993
0.5618
0.6243
0.7493

max.

0.2501
0.3126
0.3751
0.4376
0.5001
0.5626
0.6251
0.7501

min.

0.2489
0.3112
0.3737

0.4362
0.4987
0.5612
0.6237
0.7487

Decimal Diameter of plain portion
of shank
equivalent
A
of nominal
size
Before
After plating
plating

0.071
0.083
0.083
0.100
0.100
0.111
0.111
0.125

2X
pitch

0.26
0.26

0.26
0.26
0.26
0.26
0.26
0.26

Reference
only

F2)

Minimum
length of
screwed
portion of
shank

min.

0.030
0.030
0.030
0.040
0.040
0.040
0.050
0.065

max.

0.040
0.040
0.040
0.050
0.050
0.050
0.060
0.075

min.

0.015
0.015
0.015
0.015
0.015
0.015
0.015
0.015

max.

0.030
0.030
0.030
0.030
0.030
0.030
0.030

0.030

min.

0.120
0.120
0.120
0.120
0.120
0.120
0.120
0.120

0.130
0.130
0.130
0.130
0.130
0.130
0.130
0.130

0.433
0.505
0.577
0.650
0.794
0.866
1.010
1.083

0.370
0.431
0.493
0.554
0.679
0.741
0.866
0.929
0.375
0.438
0.500
0.562
0.688
0.750
0.875
0.938

G
max.

R

Depth of
chamfer

max.

D

Radius under

bolt head

min.

C

B

Thickness of
head

Dimensions in inches

max.

Width
across
corners

Width across
flats

For bearing length L, clamping length M and overall length E see Table 2
This dimension is an absolute minimum associated with maximum length M and minimum length E. It is not intended for use for manufacturing
or inspection purposes.

1)
2)

1/4 in UNF

5/16 in UNF
3/8 in UNF
7/16 in UNF
1/2 in UNF
9/16 in UNF
5/8 in UNF
3/4 in UNF

Nominal size

Table 1 — Dimensions

BS 4A 112:1992

© BSI 08-1999


BS 4A 112:1992

Table 2 — Bearing length L, clamping length M Table 2 — Bearing length L, clamping length M
and overall length E
and overall length E
Dimensions in inches

Dimensions in inches

5/16 in UNF
Part No.

1/4 in UNF

Part No.

aL

min.

M

+0
–0.03

E

+0.04
–0

aL

min.

M

+0
–0.03

E

+0.04
–0

1G
2G
3G
4G
5G

0.1
0.2
0.3
0.4
0.5

0.213
0.313
0.413
0.513
0.613

0.51
0.61
0.71
0.81
0.91

6G
7G
8G
9G
10G

0.6
0.7
0.8
0.9
1.0

0.713
0.813
0.913
1.013
1.113

1.01
1.11
1.21
1.31
1.41

11G
12G
13G
14G
15G

1.1
1.2
1.3
1.4
1.5

1.213
1.313
1.413
1.513
1.613

1.51
1.61
1.71
1.81
1.91

1E
2E
3E
4E
5E

0.1
0.2
0.3
0.4
0.5

0.201
0.301
0.401
0.501
0.601

0.50
0.60
0.70
0.80
0.90

16G
17G
18G
19G
20G

1.6
1.7
1.8
1.9
2.0

1.713
1.813
1.913
2.013
2.113

2.01
2.11
2.21
2.31
2.41

6E
7E
8E
9E
10E

0.6
0.7
0.8
0.9
1.0

0.701
0.801
0.901
0.001
0.101

1.00
1.10
1.20
1.30
1.40

21G
22G
23G
24G
25G

2.1
2.2
2.3
2.4
2.5

2.213
2.313
2.413
2.513
2.613

2.51
2.61
2.71
2.81
2.91

11E
12E
13E
14E
15E

1.1
1.2
1.3
1.4
1.5

1.201
1.301
1.401
1.501
1.601

1.50
1.60
1.70
1.80
1.90

2.6
2.7
2.8
2.9
3.0

2.713
2.813
2.913
3.013
3.113

3.01
3.11
3.21
3.31
3.41

16E
17E
18E
19E
20E

1.6
1.7
1.8
1.9
2.0

1.701
1.801
1.901
2.001
2.101

2.00
2.10
2.20
2.30
2.40

21E
22E
23E
24E
25E

2.1
2.2
2.3
2.4
2.5

2.201
2.301
2.401
2.501
2.601

2.50
2.60
2.70
2.80
2.90

26G
27G
28G
29G
30G
3/8 in UNF
1J
2J
3J
4J
5J
a See 7.3 .

0.1
0.2
0.3
0.4
0.5

0.213
0.313
0.413
0.513
0.613

0.51
0.61
0.71
0.81
0.91

a See

7.3 .

© BSI 08-1999

3


BS 4A 112:1992

Table 2 — Bearing length L, clamping length M Table 2 — Bearing length L, clamping length M
and overall length E
and overall length E
Dimensions in inches

Part No.

aL

min.

M

+0
–0.03

E

+0.04
–0

6J
7J
8J
9J
10J

0.6
0.7
0.8

0.9
1.0

0.713
0.813
0.913
1.013
1.113

1.01
1.11
1.21
1.31
1.41

11J
12J
13J
14J
15J

1.1
1.2
1.3
1.4
1.5

1.213
1.313
1.413

1.513
1.613

1.51
1.61
1.71
1.81
1.91

16J
17J
18J
19J
20J

1.6
1.7
1.8
1.9
2.0

1.713
1.813
1.913
2.013
2.113

2.01
2.11
2.21

2.31
2.41

21J
22J
23J
24J
25J

2.1
2.2
2.3
2.4
2.5

2.213
2.313
2.413
2.513
2.613

2.51
2.61
2.71
2.81
2.91

26J
27J
28J

29J
30J

2.6
2.7
2.8
2.9
3.0

2.713
2.813
2.913
3.013
3.113

3.01
3.11
3.21
3.31
3.41

31J
32J
33J
34J
35J
7/16 in UNF
1L
2L
3L

4L
5L

3.1
3.2
3.3
3.4
3.5

3.213
3.313
3.413
3.513
3.613

3.51
3.61
3.71
3.81
3.91

0.1
0.2
0.3
0.4
0.5

0.230
0.330
0.430

0.530
0.630

0.54
0.64
0.74
0.84
0.94

6L
7L

0.6
0.7

0.730
0.830

1.04
1.14

a See

4

7.3 .

Dimensions in inches

Part No.

aL

min.

M

+0
–0.03

E

+0.04
–0

8L
9L
10L

0.8
0.9
1.0

0.930
1.030
1.130

1.24
1.34
1.44

11L
12L
13L
14L
15L

1.1
1.2
1.3
1.4
1.5

1.230
1.330
1.430
1.530
1.630

1.54
1.64
1.74
1.84
1.94

16L
17L
18L
19L
20L

1.6
1.7
1.8
1.9
2.0

1.730
1.830
1.930
2.030
2.130

2.04
2.14
2.24
2.34
2.44

21L
22L
23L
24L
25L

2.1
2.2
2.3
2.4
2.5

2.230
2.330
2.430
2.530
2.630

2.54
2.64
2.74
2.84
2.94

26L
27L
28L
29L
30L

2.6
2.7
2.8
2.9
3.0

2.730
2.830
2.930
3.030
3.130

3.04
3.14
3.24
3.34
3.44

31L
32L
33L
34L
35L

3.1
3.2
3.3
3.4
3.5

3.230
3.330
3.430
3.530
3.630

3.54
3.64
3.74
3.84
3.94

36L
37L
38L
39L
40L
1/2 in UNF
1N
2N
3N
a See 7.3 .

3.6
3.7
3.8
3.9
4.0

3.730
3.830
3.930
4.030
4.130

4.04
4.14
4.24
4.34
4.44

0.1
0.2
0.3

0.230
0.330
0.430

0.54
0.64
0.74

© BSI 08-1999


BS 4A 112:1992

Table 2 — Bearing length L, clamping length M Table 2 — Bearing length L, clamping length M
and overall length E
and overall length E
Dimensions in inches

Part No.

aL

min.

M

+0
–0.03

E

+0.04
–0

4N
5N

0.4
0.5

0.530
0.630

0.84
0.94

6N
7N
8N
9N
10N

0.6
0.7
0.8
0.9

1.0

0.730
0.830
0.930
1.030
1.130

1.04
1.14
1.24
1.34
1.44

11N
12N
13N
14N
15N

1.1
1.2
1.3
1.4
1.5

1.230
1.330
1.430
1.530

1.630

1.54
1.64
1.74
1.84
1.94

16N
17N
18N
19N
20N

1.6
1.7
1.8
1.9
2.0

1.730
1.830
1.930
2.030
2.130

2.04
2.14
2.24
2.34

2.44

21N
22N
23N
24N
25N

2.1
2.2
2.3
2.4
2.5

2.230
2.330
2.430
2.530
2.630

2.54
2.64
2.74
2.84
2.94

26N
27N
28N
29N

30N

2.6
2.7
2.8
2.9
3.0

2.730
2.830
2.930
3.030
3.130

3.04
3.14
3.24
3.34
3.44

31N
32N
33N
34N
35N

3.1
3.2
3.3
3.4

3.5

3.230
3.330
3.430
3.530
3.630

3.54
3.64
3.74
3.84
3.94

36N
37N
38N
39N
40N

3.6
3.7
3.8
3.9
4.0

3.730
3.830
3.930
4.030

4.130

4.04
4.14
4.24
4.34
4.44

a See

7.3 .

© BSI 08-1999

Dimensions in inches

Part No.
41N
42N
43N
44N
45N
9/16 in UNF
1P
2P
3P
4P
5P
6P
7P

8P
9P
10P
11P
12P
13P
14P
15P
16P
17P
18P
19P
20P
21P
22P
23P
24P
25P
26P
27P
28P
29P
30P
31P
32P
a See 7.3 .

aL

min.

M

+0
–0.03

E

+0.04
–0

4.1
4.2
4.3
4.4
4.5

4.230
4.330
4.430
4.530
4.630

4.54
4.64
4.74
4.84
4.94

0.1

0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2.0
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
3.0
3.1

3.2

0.241
0.341
0.441
0.541
0.641
0.741
0.841
0.941
1.041
1.141
1.241
1.341
1.441
1.541
1.641
1.741
1.841
1.941
2.041
2.141
2.241
2.341
2.441
2.541
2.641
2.741
2.841
2.941

3.041
3.141
3.241
3.341

0.55
0.65
0.75
0.85
0.95
1.05
1.15
1.25
1.35
1.45
1.55
1.65
1.75
1.85
1.95
2.05
2.15
2.25
2.35
2.45
2.55
2.65
2.75
2.85
2.95

3.05
3.15
3.25
3.35
3.45
3.55
3.65

5


BS 4A 112:1992

Table 2 — Bearing length L, clamping length M Table 2 — Bearing length L, clamping length M
and overall length E
and overall length E
Dimensions in inches

Part No.

aL

min.

M

+0
–0.03

E

+0.04
–0

33P
34P
35P

3.3
3.4
3.5

3.441
3.541
3.641

3.75
3.85
3.95

36P
37P
38P
39P
40P
41P
42P
43P
44P
45P

5/8 in UNF
1Q
2Q
3Q
4Q
5Q

3.6
3.7
3.8
3.9
4.0
4.1
4.2
4.3
4.4
4.5

3.741
3.841
3.941
4.041
4.141
4.241
4.341
4.441
4.541
4.641

4.05

4.15
4.25
4.35
4.45
4.55
4.65
4.75
4.85
4.95

0.1
0.2
0.3
0.4
0.5

0.241
0.341
0.441
0.541
0.641

0.56
0.66
0.76
0.86
0.96

6Q
7Q

8Q
9Q
10Q

0.6
0.7
0.8
0.9
1.0

0.741
0.841
0.941
1.041
1.141

1.06
1.16
1.26
1.36
1.46

11Q
12Q
13Q
14Q
15Q

1.1
1.2

1.3
1.4
1.5

1.241
1.341
1.441
1.541
1.641

1.56
1.66
1.76
1.86
1.96

16Q
17Q
18Q
19Q
20Q

1.6
1.7
1.8
1.9
2.0

1.741
1.841

1.941
2.041
2.141

2.06
2.16
2.26
2.36
2.46

21Q
22Q
23Q

2.1
2.2
2.3

2.241
2.341
2.441

2.56
2.66
2.76

a See

6

7.3 .

Dimensions in inches

Part No.

aL

min.

M

+0
–0.03

E

+0.04
–0

24Q
25Q

2.4
2.5

2.541
2.641

2.86

2.96

26Q
27Q
28Q
29Q
30Q

2.6
2.7
2.8
2.9
3.0

2.741
2.841
2.941
3.041
3.141

3.06
3.16
3.26
3.36
3.46

31Q
32Q
33Q
34Q

35Q

3.1
3.2
3.3
3.4
3.5

3.241
3.341
3.441
3.541
3.641

3.56
3.66
3.76
3.86
3.96

36Q
37Q
38Q
39Q
40Q

3.6
3.7
3.8
3.9

4.0

3.741
3.841
3.941
4.014
4.141

4.06
4.16
4.26
4.36
4.46

41Q
42Q
43Q
44Q
45Q
3/4 in UNF
1S
2S
3S
4S
5S

4.1
4.2
4.3
4.4

4.5

4.241
4.341
4.441
4.541
4.641

4.56
4.66
4.76
4.86
4.96

0.1
0.2
0.3
0.4
0.5

0.255
0.355
0.455
0.555
0.655

0.59
0.69
0.79
0.89

0.99

6S
7S
8S
9S
10S

0.6
0.7
0.8
0.9
1.0

0.755
0.855
0.955
1.055
1.155

1.09
1.19
1.29
1.39
1.49

11S
12S
13S

1.1
1.2
1.3

1.255
1.355
1.455

1.59
1.69
1.79

a See

7.3 .

© BSI 08-1999


BS 4A 112:1992

Table 2 — Bearing length L, clamping length M
and overall length E
Dimensions in inches

Part No.

aL

min.

M

+0
–0.03

E

+0.04
–0

14S
15S

1.4
1.5

1.555
1.655

1.89
1.99

16S
17S
18S
19S
20S

1.6

1.7
1.8
1.9
2.0

1.755
1.855
1.955
2.055
2.155

2.09
2.19
2.29
2.39
2.49

21S
22S
23S
24S
25S

2.1
2.2
2.3
2.4
2.5

2.255

2.355
2.455
2.555
2.655

2.59
2.69
2.79
2.89
2.99

26S
27S
28S
29S
30S

2.6
2.7
2.8
2.9
3.0

2.755
2.855
2.955
3.055
3.155

3.09

3.19
3.29
3.39
3.49

31S
32S
33S
34S
35S

3.1
3.2
3.3
3.4
3.5

3.255
3.355
3.455
3.555
3.655

3.59
3.69
3.79
3.89
3.99

36S

37S
38S
39S
40S

3.6
3.7
3.8
3.9
4.0

3.755
3.855
3.955
4.055
4.155

4.09
4.19
4.29
4.39
4.49

41S
42S
43S
44S
45S

4.1

4.2
4.3
4.4
4.5

4.255
4.355
4.455
4.555
4.655

4.59
4.69
4.79
4.89
4.99

a See

7.3 .

© BSI 08-1999

7


8

blank

BS 4A 112:1992

List of references (see clause 2)
Normative references
BSI standards publications

BRITISH STANDARDS INSTITUTION, London

BS 3A 100:1991, Specification for general requirements for bolts and free running nuts of tensile strength
not exceeding 1249 MPa1) .

BS 2S 147:1976, Specification for 0. 5 % nickel-chromium-molybdenum steel bars for the manufacture of
forged bolts and forged nuts.

BS 2S 149:1976, Specification for 1. 75 % nickel-chromium-molybdenum steel bars for the manufacture of
forged bolts and forged nuts.

BS S 154:1976, Specification.

2½ % nickel-chromium-molybdenum steel billets, bars, forgings and
parts (880–1080 MPa: limiting ruling section 150 mm).

BS S 158:1977, Specification for 1 % chromium-molybdenum steel bars for the manufacture of forged bolts
and forged nuts.

Other references
[1] DEF STAN 03-19 Electro-Deposition of Cadmium , available from Ministry of Defence (Procurement
Executive), Directorate of Standardization, Kentigern House, 65 Brown St., Glasgow G2 8EX.

Informative references
BSI standards publications

BRITISH STANDARDS INSTITUTION, London

BS 3A 109:1985, Specification for steel shear bolts (Unified hexagons and United threads)2) .
BS 2A 110:1962, Specification for steel nuts (Unified hexagons and Unified threads) for shear bolts for
aircraft2) .

BS 2S 96:1964, Specification for 2½ per cent nickel-chromium-molybdenum steel (55/65 tonf/sq in: limiting
ruling section 6 in)3) .

1) Edition current at time of publication
2) Referred to in the foreword only.
3) Withdrawn.

© BSI 08-1999

(see clauses 3 and 8 ).


BS 4A 112:
1992

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