[[TitleIndustry]]

BA vs BSW vs BSF vs BSPC vs BSPP vs BSPT thread difference Fittings

Date:Apr 11, 2020

British Association standard screw threads, or BA screw threads, are a largely obsolete set of small screw threads, the largest being 0BA at 6 mm diameter. They were used for miniature instruments and modelling.BA threads are still used in some precision instruments, such as optics and moving-coil meters, the angle of the thread is 47.5°and the depth of thread is 0.6 times the pitch with rounded tops and bottoms.

 

BA sizes are specified by the following British Standards:

BS 57:1951 — B.A. screws, bolts and nuts

BS 93:1951 — Specification for British Association (B.A.) screw threads with tolerances for sizes 0 B.A. to 16 B.A.

BS 93:2008 — British Association (B.A.) screw threads — Requirements

BA thread is primarily electronic/electrical, moving coil meters and to mount optical lenses.

A

Thread pitch

Outside diameter

Threads density

Outside diameter

Spanner

(mm)

(mm)

(tpi)

(in)

(in)

(mm)

(in)

0

1.00

6.00

25.40

0.2362

10.5000

0.4134

1

0.90

5.30

28.22

0.2087

9.2750

0.3652

2

0.81

4.70

31.36

0.1850

8.2250

0.3238

3

0.73

4.10

34.79

0.1614

7.1750

0.2825

4

0.66

3.60

38.48

0.1417

6.3000

0.2480

5

0.59

3.20

43.05

0.1260

5.6000

0.2205

6

0.53

2.80

47.92

0.1102

4.9000

0.1929

7

0.48

2.50

52.92

0.0984

4.3750

0.1722

8

0.43

2.20

59.07

0.0866

3.8500

0.1516

9

0.39

1.90

65.13

0.0748

3.3250

0.1309

10

0.35

1.70

72.57

0.0669

2.9750

0.1171

25

0.072

0.25

352.78

0.0098

0.4375

0.0172

British Standard Whitworth (BSW) is an imperial-unit-based screw thread standard, Whitworth's new standard specified a 55° thread angle, in form of the 15 British standard pipe threads defined in ISO 7, which are commonly used in water supply, cooling, pneumatic, and hydraulic systems. Two types of threads are distinguished:

Parallel (straight) threads, British Standard Pipe Parallel thread (BSPP; originally also known as[1] British Standard Pipe Fitting thread/BSPF and British Standard Pipe Mechanical thread/BSPM), which have a constant diameter; denoted by the letter G.

Taper threads, British Standard Pipe Taper thread (BSPT), whose diameter increases or decreases along the length of the thread; denoted by the letter R.

British Standard Pipe (BSP) technical standards for screw threads that has been adopted internationally for interconnecting and sealing pipes and fittings by mating an external (male) thread with an internal (female) thread. It has been adopted as standard in plumbing and pipe fitting.

 British Standard Fine (BSF) has a finer thread pitch and smaller thread depth. This is more like the modern "mechanical" screw and was used for fine machinery and for steel bolts.

 Cycle Engineers' Institute (CEI) or British Standard Cycle (BSC) , which replaced the Cycle Engineers' Institute (CEI) standard was used on British bicycles and motorcycles. It uses a thread angle of 60°compared to the Whitworth 55°and very fine thread pitches.

 

British Standard Buttress Threads (BS 1657:1950)

British Standard for Spark Plugs BS 45:1972

British Standard Brass a fixed pitch 26 TPI thread

 

Whitworth thread sizes

Hex head spanner wrench sizes

Size

BS 190

BS 1083

DIN

(in)

(in)

(mm)

(in)

(mm)

(mm)

1⁄8

0.338

8.6

3⁄16

0.445

11.3

1⁄4

0.525

13.3

0.445

11.3

11

5⁄16

0.600

15.2

0.525

13.3

14

3⁄8

0.710

18.0

0.600

15.2

17

7⁄16

0.820

20.8

0.710

18.0

19

1⁄2

0.920

23.4

0.820

20.8

22

9⁄16

1.010

25.7

0.920

23.4

5⁄8

1.100

27.9

1.010

25.7

27

3⁄4

1.300

33.0

1.200

30.5

32

7⁄8

1.480

37.6

1.300

33.0

36

1

1.670

42.4

1.480

37.6

41

1 1⁄8

1.860

47.2

1.670

42.4

1 1⁄4

2.050

52.1

1.860

47.2

1 1⁄2

2.410

61.2

2.220

56.4

1 3⁄4

2.760

70.1

2.580

65.5

2

3.150

80.0

2.760

70.1


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