Bsi bs a 254, bs a 255, bs a 256, bs a 257, bs a 258, bs a 259 1976 (2008)

BRITISH STANDARD AEROSPACE SERIES

Hexagonal head
titanium alloy
bolts 160 000 lbf/in2
(1100 MPa)

UDC 629.7.02:621.882.211:669.295.5

BS A 254,
BS A 255,
BS A 256,
BS A 257,
BS A 258,
BS A 259:1976
Incorporating
Amendment Nos. 1
and 2

Confirmed
April 2008


BS A 254, BS A 255, BS A 256, BS A 257,
BS A 258, BS A 259:1976

Foreword
This British Standard has been prepared to provide a range
of 160 000 lbf/in2 (1 100 MPa) to 180 000 lbf/in2 (1 250 MPa) titanium alloy
bolts with UNJ profile threads and close tolerance shanks for aerospace use.
The lengths of the bolts are in fractional increments. When considering the use

of cadmium plated titanium bolts, attention is drawn to DARD Technical
Circular No. 292 which recommends certain limitations on their use.
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 British Standard, having
been approved by the
Aerospace Industry
Standards Committee,
was published under the
authority of the Executive
Board on
31 March 1976
© BSI 02-2000
The following BSI references
relate to the work on this
standard:
Committee reference ACE/12
Draft for comment 72/37963 DC
ISBN 0 580 08706 9

This document comprises a front cover, an inside front cover, pages i and ii,
pages 1 to 8 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.
Amendments issued since publication

Amd. No.
2647
2812

Date of issue
July 1978
April 1979

Comments
Indicated by a sideline in the margin


BS A 254, BS A 255, BS A 256, BS A 257,
BS A 258, BS A 259:1976

Contents
Page
Foreword
Inside front cover
1 Scope
1
2 References
1
3 General requirements
1
4 Example of call up
7

5 Identification and marking
7
Appendix A Table for the conversion of inches to millimetre equivalents
8
Figure 1 — Basic dimensions
1
Figure 2 — Alternative bolt head manufacturers option. Washer
face and/or dimpled head
1
Figure 3 — Typical disposition of the various markings
7
Table 1 — Dimensions (standard shank diameters)
2
Table 2 — Oversize shank diameters
2
Table 3 — Material
3
Table 4 — Bearing length L, overall length E and dimension M
4

© BSI 02-2000

i


ii

blank

BS A 254, BS A 255, BS A 256, BS A 257,
BS A 258, BS A 259:1976

1 Scope

This British Standard specifies the materials, dimensions, finish and inspection requirements for titanium
alloy bolts with hexagonal heads and UNJ thread for aerospace use.

2 References

This standard makes reference to the following British Standards and Ministry of Defence publications:
BS 4084, Unified screw threads of “UNJ” basic profile.
BS A 101, General requirements for titanium bolts.
BS A 242-245, Hexagonal castle nuts (of class 3B UNJ thread).
BS TA 28, Forging stock and wire of titanium-aluminium-vanadium alloy

(tensile strength 1 100–1 300 MPa) (limiting ruling section 20 mm).
DTD 904, Cadmium plating.
DTD 942, Anodising of titanium and titanium alloys.
DEF STAN 91–19/1, Lubricant, solid film, heat cured.

The latest editions of these standards shall be used.

NOTE The values in imperial units are to be regarded as the standard. The table in Appendix A provides millimetre equivalents of
inch dimensions and is based on the tables in BS 350 “Conversion factors and tables”.

3 General requirements

3.1 The bolts shall be manufactured, inspected and tested in accordance with the requirements of BS A 101.
3.2 All bolts shall conform to the dimensions and tolerances given in Table 1, Table 2 and Table 4, and

Figure 1 and Figure 2. Unless otherwise specified, the dimensions are those before the application of
surface treatment. The material requirements shall be as specified.

Figure 1 — Basic
dimensions

© BSI 02-2000

Figure 2 — Alternative
bolt head manufacturers
option. Washer face
and/or dimpled head

1


BS A 254, BS A 255, BS A 256, BS A 257,
BS A 258, BS A 259:1976

1

2

3

(1)

Table 1 — Dimensions (standard shank diameters)
4

03
04
05
06
07
08

10–32
1/4–28
5/16–24
3/8–24
7/16–20
1/2–20

13
Diameter
code
03
04
05
06
07
08

0.1900
0.2500
0.3125
0.3750
0.4375

0.5000

14

15

0.1895
0.2495
0.3120
0.3745
0.4370
0.4995

0.125
0.140
0.171
0.203
0.234
0.265

0.1890
0.2490
0.3115
0.3740
0.4365
0.4990

16

17

R

Min.

0.110
0.125
0.156
0.188
0.219
0.250

6

7

ÌA

8

Type
BS A 257 (3)
Max.

2 × Pitch

Min.

0.1895
0.2495

0.3120
0.3745
0.4370
0.4995

9

T

0.1885
0.2485
0.3110
0.3735
0.4360
0.4985

Ref
Min.

0.063
0.071
0.083
0.083
0.100
0.100

0.381
0.443
0.506
0.615

0.631
0.757

Table 1 — Dimensions (standard shank diameters)

D

Max.

5

Type:
BS A 254
BS A 255
BS A 256 (2)
Max.
Min.

Diameter Nominal Nominal
shank
Code
thread
diameter
size
UNJF

ÌA

Max.

Min.

0.025
0.025
0.025
0.025
0.030
0.030

0.015
0.015
0.015
0.015
0.020
0.020

18

19

ÌG

ÌJ

ÌK

(9)
0.073
0.083
0.104

0.125
0.146
0.167

Min.

± 0.020

0.130
0.184
0.239
0.302
0.354
0.416

10

11

B

Max.

12
C

Min.

Min.

0.376
0.439
0.502
0.564
0.690
0.752

0.367
0.430
0.492
0.553
0.679
0.741

0.419
0.491
0.561
0.631
0.775
0.845

20

21

22

23

24

25

(8)

N

ÌP

S

ÌU

W

+0.008
–0
0.063
0.063
0.063
0.063
0.079
0.079

+0.005
–0
0.047
0.047
0.047
0.047

0.063
0.063

+0
–0.012
0.020
0.020
0.020
0.020
0.024
0.024

0.357
0.420
0.482
0.543
0.669
0.731

+0.015
–0
0.073
0.083
0.104
0.125
0.141
0.167

± 0.010

0.19
0.25
0.31
0.38
0.44
0.50

(1) The screw threads shall conform to the basic thread form, diameter and related pitches specified in BS 4084, “Unified screw threads
of “UNJ” basic profile” (class 3A).
(2) Before application of protective treatment.
(3) After application of protective treatment.
(4) The runout of the thread shall comply with the relevant requirements of SBAC publication RS 678.
(5) See Table 4 for length dimensions “L”, “E” and “M”.
(6) To suit hexagonal castle nuts specified in BS A242–245.
(7) Holes shall have the sharp edges removed.
(8) Kmax = Bmin.
(9) For diameter codes 03, 04 and 05 the tolerance shall be +0.005.
0
For diameter codes 06, 07 and 08 the tolerance shall be +0.0070.
0

Table 2 — Oversize shank diameters

All dimensions in inches

1

2

Diameter

code

Nominal
thread
size UNJF

03
04
05
06
07
08

10–32
1/4–28
5/16–24
3/8–24
7/16–20
1/2–20

2

3

4
5
First oversize (code X)

ÌA

Type:
BS A 254
BS A 255
BS A 256 (2)
Max.
Min.

0.2026
0.2651
0.3276
0.3901
0.4526
0.5151

0.2021
0.2646
0.3271
0.3896
0.4521
0.5146

6

ÌA

Type:
BS A 257 (3)
Max.

0.2026

0.2651
0.3276
0.3901
0.4526
0.5151

Min.

0.2016
0.2641
0.3266
0.3891
0.4516
0.5141

7

8
9
Second oversize (code Y)

ÌA

Type:
BS A 254
BS A 255
BS A 256(2)
Max.
Min.

0.2182
0.2807
0.3432
0.4057
0.4682
0.5307

0.2177
0.2802
0.3427
0.4052
0.4677
0.5302

10

ÌA

Type:
BS A 257 (3)
Max.

0.2182
0.2807
0.3432
0.4057
0.4682
0.5307

Min.

0.2172
0.2797
0.3422
0.4047
0.4672
0.5297

© BSI 02-2000


BS A 254, BS A 255, BS A 256, BS A 257,
BS A 258, BS A 259:1976

Basic BS number

BS A 254
BS A 255

BS A 256
BS A 257
BS A 258
BS A 259

© BSI 02-2000

Type of material

Titanium alloy to
BS TA 28

Table 3 — Material

Mechanical properties

Protective treatment

0.2 % proof stress: not less
None
than 140 000 lbf/in2 (970 MPa)
Anodized in accordance with
DTD 942
Tensile strength: not less than Anodized in accordance with
DTD 942 + MoS 2
160 000 lbf/in2 (1 100 MPa)
in accordance with DEF. STAN
and not more than
91–19/1
180 000 lbf/in2 (1 250 MPa)
Cadmium plated in accordance
with DTD 904, on nickel strike
Elongation on 5.65 Ỉ S0:
Not yet allocated
not less than 8 %
Not yet allocated

3


BS A 254, BS A 255, BS A 256, BS A 257,

BS A 258, BS A 259:1976

Table 4 — Bearing length L, overall length E and dimension M
NOTE Unallocated diameter/length codes shall not be used.

All dimensions in inches

10–32 UNJF
1/4–28 UNJF
5/16–24 UNJF
Dia./length
L
M
E
Dia./length
L
M
E
Dia./length
L
M
E
± 0.010 ± 0.015 ± 0.010
± 0.010 ± 0.015 ± 0.010
± 0.010 ± 0.015 ± 0.010
code
code
code

0301

0302
0303
0304
0305

0.062
0.125
0.188
0.250
0.312

0.468
0.531
0.594
0.656
0.718

0.333
0.396
0.459
0.521
0.583

0401
0402
0403
0404
0405

0.062

0.125
0.188
0.250
0.312

0.530
0.593
0.656
0.718
0.780

0.365
0.428
0.491
0.553
0.615

0501
0502
0503
0504
0505

0.062
0.125
0.188
0.250
0.312

0.593

0.656
0.719
0.781
0.843

0.423
0.486
0.549
0.611
0.673

0306
0307
0308
0309
0310

0.375
0.438
0.500
0.562
0.625

0.781
0.844
0.906
0.968
1.031

0.646

0.709
0.771
0.833
0.896

0406
0407
0408
0409
0410

0.375
0.438
0.500
0.562
0.625

0.843
0.906
0.968
1.030
1.093

0.678
0.741
0.803
0.865
0.928

0506

0507
0508
0509
0510

0.375
0.438
0.500
0.562
0.625

0.906
0.969
1.031
1.093
1.156

0.736
0.799
0.861
0.923
0.986

0311
0312
0313
0314
0315

0.688

0.750
0.812
0.875
0.938

1.094
1.156
1.218
1.281
1.344

0.959
1.021
1.083
1.146
1.209

0411
0412
0413
0414
0415

0.688
0.750
0.812
0.875
0.938

1.156

1.218
1.280
1.343
1.406

0.991
1.053
1.115
1.178
1.241

0511
0512
0513
0514
0515

0.688
0.750
0.812
0.875
0.938

1.219
1.281
1.343
1.406
1.469

1.049

1.111
1.173
1.236
1.299

0316
0317
0318
0319
0320

1.000
1.062
1.125
1.188
1.250

1.406
1.468
1.531
1.594
1.656

1.271
1.333
1.396
1.459
1.521

0416

0417
0418
0419
0420

1.000
1.062
1.125
1.188
1.250

1.468
1.530
1.593
1.656
1.718

1.303
1.365
1.428
1.491
1.553

0516
0517
0518
0519
0520

1.000

1.062
1.125
1.188
1.250

1.531
1.593
1.656
1.719
1.781

1.361
1.423
1.486
1.549
1.611

0321
0322
0323
0324
0325

1.312
1.375
1.438
1.500
1.562

1.718

1.781
1.844
1.906
1.968

1.583
1.646
1.709
1.771
1.833

0421
0422
0423
0424
0425

1.312
1.375
1.438
1.500
1.562

1.780
1.843
1.906
1.968
2.030

1.615

1.678
1.741
1.803
1.865

0521
0522
0523
0524
0525

1.312
1.375
1.438
1.500
1.562

1.843
1.906
1.969
2.031
2.093

1.673
1.736
1.799
1.861
1.923

0326

0327
0328
0329
0330

1.625
1.688
1.750
1.812
1.875

2.031
2.094
2.156
2.218
2.281

1.896
1.959
2.021
2.083
2.146

0426
0427
0428
0429
0430

1.625

1.688
1.750
1.812
1.875

2.093
2.156
2.218
2.280
2.343

1.928
1.991
2.053
2.115
2.178

0526
0527
0528
0529
0530

1.625
1.688
1.750
1.812
1.875

2.156

2.219
2.281
2.343
2.406

1.986
2.049
2.111
2.173
2.236

0331
0332
0334
0336
0338
0340

1.938
2.000
2.125
2.250
2.375
2.500

2.344
2.406
2.531
2.656
2.781

2.906

2.209
2.271
1.396
2.521
2.646
2.771

0431
0432
0434
0436
0438
0440

1.938
2.000
2.125
2.250
2.375
2.500

2.406
2.468
2.593
2.718
2.843
2.968

2.241
2.303
2.428
2.553
2.678
2.803

0531
0532
0534
0536
0538
0540

1.938
2.000
2.125
2.250
2.375
2.500

2.469
2.531
2.656
2.781
2.906
3.031

2.299
2.361

2.486
2.611
2.736
2.861

0342
0344
0346
0348
0350

2.625
2.750
2.875
3.000
3.125

3.031
3.156
3.281
3.406
3.531

2.896
3.021
3.146
3.271
3.396

0442

0444
0446
0448
0450

2.625
2.750
2.875
3.000
3.125

3.093
3.218
3.343
3.468
3.593

2.928
3.053
3.178
3.303
3.428

0542
0544
0546
0548
0550

2.625

2.750
2.875
3.000
3.125

3.156
3.281
3.406
3.531
3.656

2.986
3.111
3.236
3.361
3.486

4

© BSI 02-2000


BS A 254, BS A 255, BS A 256, BS A 257,
BS A 258, BS A 259:1976

Table 4 — Bearing length L, overall length E and dimension M
All dimensions in inches

10–32 UNJF
1/4–28 UNJF

5/16–24 UNJF
Dia./length
L
M
E
Dia./length
L
M
E
Dia./length
L
M
E
± 0.010 ± 0.015 ± 0.010
± 0.010 ± 0.015 ± 0.010
± 0.010 ± 0.015 ± 0.010
code
code
code
0352
0354
0356
0358
0360

3.250
3.375
3.500
3.625
3.750

3.656
3.781
3.906
4.031
4.156

3.521
3.646
3.771
3.896
4.021

0452
0454
0456
0458
0460

3.250
3.375
3.500
3.625
3.750

3.718
3.843
3.968
4.093
4.218

3.553
3.678
3.803
3.928
4.053

0552
0554
0556
0558
0560

3.250
3.375
3.500
3.625
3.750

3.781
3.906
4.031
4.156
4.281

3.611
3.736
3.861
3.986
4.111

0362
0364
0366
0368
0370

3.875
4.000
4.125
4.250
4.375

4.281
4.406
4.531
4.656
4.781

4.146
4.271
4.396
4.521
4.646

0462
0464
0466
0468
0470

3.875
4.000
4.125
4.250
4.375

4.343
4.468
4.593
4.718
4.843

4.178
4.303
4.428
4.553
4.678

0562
0564
0566
0568
0570

3.875
4.000
4.125
4.250
4.375

4.406
4.531
4.656
4.781
4.906

4.236
4.361
4.486
4.611
4.736

0372
0374
0376
0378
0380

4.500
4.625
4.750
4.875
5.000

4.906
5.031
5.156
5.281
5.406

4.771
4.896
5.021
5.146
5.271

0472
0474
0476
0478
0480

4.500
4.625
4.750
4.875
5.000

4.968
5.093
5.218
5.343
5.468

4.803
4.928
5.053
5.178
5.303

0572
0574
0576
0578
0580

4.500
4.625
4.750
4.875
5.000

5.031
5.156
5.281
5.406
5.531

4.861
4.986
5.111
5.236
5.361

0382
0384
0386
0388
0390

5.125
5.250
5.375
5.500
5.625

5.531
5.656
5.781
5.906
6.031

5.396
5.521
5.646
5.771
5.896

0482
0484
0486
0488
0490

5.125
5.250
5.375
5.500
5.625

5.593
5.718
5.843
5.968
6.093

5.428
5.553
5.678
5.803
5.928

0582
0584
0586
0588
0590

5.125
5.250
5.375
5.500
5.625

5.656
5.781
5.906
6.031
6.156

5.486
5.611
5.736
5.861
5.986

0392
0394
0396

5.750
5.875
6.00

6.156
6.281
6.406

6.021
6.146
6.271

0492
0494
0496

5.750
5.875
6.000

6.218
6.343
6.468

6.053
6.178
6.303

0592
0594
0596

5.750
5.875
6.000

6.281
6.406
6.531

6.111
6.236
6.361

© BSI 02-2000

5

BS A 254, BS A 255, BS A 256, BS A 257,
BS A 258, BS A 259:1976

Table 4 — Bearing length L, overall length E and dimension M
All dimensions in inches

3/8–24 UNJF
7/16–20 UNJF
1/2–20 UNJF
Dia./length
L
M
E
Dia./length
L
M
E
Dia./length
L
M
E
± 0.010 ± 0.015 ± 0.010
± 0.010 ± 0.015 ± 0.010
± 0.010 ± 0.015 ± 0.010
code
code
code
0602
0603
0604

0605

0.125
0.188
0.250
0.312

0.766
0.829
0.891
0.954

0.551
0.614
0.676
0.739

0702
0703
0704
0705

0.125
0.188
0.250
0.312

0.781
0.844
0.906

0.968

0.616
0.679
0.741
0.803

0802
0803
0804
0805

0.125
0.188
0.250
0.312

0.907
0.970
1.032
1.094

0.717
0.780
0.842
0.904

0606
0607
0608

0609
0610

0.375
0.438
0.500
0.562
0.625

1.016
1.079
1.141
1.203
1.266

0.801
0.864
0.926
0.988
1.051

0706
0707
0708
0709
0710

0.375
0.438
0.500

0.562
0.625

1.031
1.094
1.156
1.218
1.281

0.866
0.929
0.911
1.053
1.116

0806
0807
0808
0809
0810

0.375
0.438
0.500
0.562
0.625

1.157
1.220
1.282

1.334
1.407

0.967
1.030
1.092
1.144
1.217

0611
0612
0613
0614
0615

0.688
0.750
0.812
0.875
0.938

1.329
1.391
1.453
1.516
1.579

1.114
1.176
1.238

1.301
1.364

0711
0712
0713
0714
0715

0.688
0.750
0.812
0.875
0.938

1.344
1.406
1.468
1.531
1.594

1.179
1.241
1.303
1.366
1.429

0811
0812
0813

0814
0815

0.688
0.750
0.812
0.875
0.938

1.470
1.532
1.594
1.657
1.720

1.280
1.342
1.404
1.467
1.530

0616
0617
0618
0619
0620

1.000
1.062
1.125

1.188
1.250

1.641
1.703
1.766
1.829
1.891

1.426
1.488
1.551
1.614
1.676

0716
0717
0718
0719
0720

1.000
1.062
1.125
1.188
1.250

1.656
1.718
1.781

1.844
1.906

1.491
1.553
1.616
1.679
1.741

0816
0817
0818
0819
0820

1.000
1.062
1.125
1.188
1.250

1.782
1.844
1.907
1.970
2.032

1.592
1.654
1.717

1.780
1.842

0621
0622
0623
0624
0625

1.312
1.375
1.438
1.500
1.562

1.953
2.016
2.079
2.141
2.203

1.738
1.801
1.864
1.926
1.988

0721
0722
0723

0724
0725

1.312
1.375
1.438
1.500
1.562

1.968
2.031
2.094
2.156
2.218

1.803
1.866
1.929
1.991
2.053

0821
0822
0823
0824
0825

1.312
1.375
1.438

1.500
1.562

2.094
2.157
2.220
2.282
2.344

1.904
1.967
2.030
2.092
2.154

0626
0627
0628
0629
0630

1.625
1.688
1.750
1.812
1.875

2.266
2.329
2.391

2.453
2.516

2.051
2.114
2.176
2.238
2.301

0726
0727
0728
0729
0730

1.625
1.688
1.750
1.812
1.875

2.281
2.344
2.406
2.468
2.531

2.116
2.179
2.241

2.303
2.366

0826
0827
0828
0829
0830

1.625
1.688
1.750
1.812
1.875

2.407
2.470
2.532
2.594
2.657

2.217
2.280
2.342
2.404
2.467

0631
0632
0634

0636
0638
0640

1.938
2.000
2.125
2.250
2.375
2.500

2.579
2.641
2.766
2.891
3.016
3.141

2.364
2.426
2.551
2.676
2.801
2.926

0731
0732
0734
0736
0738

0740

1.938
2.000
2.125
2.250
2.375
2.500

2.594
2.656
2.781
2.906
3.031
3.156

2.429
2.491
2.616
2.741
2.866
2.991

0831
0832
0834
0836
0838
0840

1.938
2.000
2.125
2.250
2.375
2.500

2.720
2.782
2.907
3.032
3.157
3.282

2.530
2.592
2.717
2.842
2.967
3.092

0642
0644
0646
0648
0650

2.625
2.750
2.875

3.000
3.125

3.266
3.391
3.516
3.641
3.766

3.051
3.176
3.301
3.426
3.551

0742
0744
0746
0748
0750

2.625
2.750
2.875
3.000
3.125

3.281
3.406
3.531

3.656
3.781

3.116
3.241
3.366
3.491
3.616

0842
0844
0846
0848
0850

2.625
2.750
2.875
3.000
3.125

3.407
3.532
3.657
3.782
3.907

3.217
3.342
3.467

3.592
3.717

0652
0654
0656
0658
0660

3.250
3.375
3.500
3.625
3.750

3.891
4.016
4.141
4.266
4.391

3.676
3.801
3.926
4.051
4.176

0752
0754
0756

0758
0760

3.250
3.375
3.500
3.625
3.750

3.906
4.031
4.156
4.281
4.406

3.741
3.866
3.991
4.116
4.241

0852
0854
0856
0858
0860

3.250
3.375
3.500

3.625
3.750

4.032
4.157
4.282
4.407
4.532

3.842
3.967
4.092
4.217
4.342

0662
0664
0666
0668
0670

3.875
4.000
4.125
4.250
4.375

4.516
4.641
4.766

4.891
5.016

4.301
4.426
4.551
4.676
4.801

0762
0764
0766
0768
0770

3.875
4.000
4.125
4.250
4.375

4.531
4.656
4.781
4.906
5.031

4.366
4.491
4.616

4.741
4.866

0862
0864
0866
0868
0870

3.875
4.000
4.125
4.250
4.375

4.657
4.782
4.907
5.032
5.157

4.467

6

4.592
4.717
4.842
4.967

© BSI 02-2000


BS A 254, BS A 255, BS A 256, BS A 257,
BS A 258, BS A 259:1976

Table 4 — Bearing length L, overall length E and dimension M

All dimensions in inches

3/8–24 UNJF
7/16–20 UNJF
1/2–20 UNJF
Dia./length
L
M
E
Dia./length
L
M
E
Dia./length
L
M
E
± 0.010 ± 0.015 ± 0.010
± 0.010 ± 0.015 ± 0.010
± 0.010 ± 0.015 ± 0.010
code
code

code

0672
0674
0676
0678
0680

4.500
4.625
4.750
4.875
5.000

5.141
5.266
5.391
5.516
5.641

4.926
5.051
5.176
5.301
5.426

0772
0774
0776
0778

0780

4.500
4.625
4.750
4.875
5.000

5.156
5.281
5.406
5.531
5.656

4.991
5.116
5.241
5.366
5.491

0872
0874
0876
0878
0880

4.500
4.625
4.750
4.875

5.000

5.282
5.407
5.532
5.657
5.782

5.092
5.217
5.342
5.467
5.592

0682
0684
0686
0688
0690

5.125
5.250
5.375
5.500
5.625

5.766
5.891
6.016
6.141

6.266

5.551
5.676
5.801
5.926
6.051

0782
0784
0786
0788
0790

5.125
5.250
5.375
5.500
5.625

5.781
5.906
6.031
6.156
6.281

5.616
5.741
5.866
5.991

6.116

0882
0884
0886
0888
0890

5.125
5.250
5.375
5.500
5.625

5.907
6.032
6.157
6.282
6.407

5.717
5.842
5.967
6.092
6.217

0692
0694
0696

5.750
5.875
6.000

6.391
6.516
6.641

6.176
6.301
6.426

0792
0794
0796

5.750
5.875
6.000

6.406
6.531
6.656

6.241
6.366
6.491

0892
0894

0896

5.750
5.875
6.000

6.532
6.657
6.782

6.342
6.467
6.592

4 Example of call up:

5 Identification and marking

The bolts shall have the manufacturer’s identification and full part number applied to the upper face of the
head except for the 10–32 UNJF size in which case the diameter code (03) may be omitted.
The method of marking bolts and packages shall be as specified in BS A 101.
Figure 3 shows a typical disposition of the various markings

Figure 3 — Typical disposition of the various markings

© BSI 02-2000

7

BS A 254, BS A 255, BS A 256, BS A 257,
BS A 258, BS A 259:1976

Appendix A Table for the conversion of inches to millimetre equivalents
in

1
2
3
4
5
6
7
8
9
10

8

mm

25.4
50.8
76.2
101.6
127.0
152.4
177.8
203.2
228.6

254.0

© BSI 02-2000


blank


BS A 254,
BS A 255,
BS A 256,
BS A 257,
BS A 258,
BS A 259:1976

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