Thread table - inch thread dimensions

Dimensions

Thread type

outside diameter

dimensions [mm]

inside diameter

dimensions [mm]

number of turns per inch

thread pitch

[mm]

inch pipe

BSP

BSPT

metric

inch

UNF UN UNS

(JIC, ORFS)

inch pipe

NPT

NPTF

7,8 ÷ 8

6,8 ÷ 7

 

1

 

M8x1

 

 

9,3 ÷ 9,7

8,5 ÷ 8,9

28

(0,91)

1/8

 

 

 

9,3 ÷ 9,7

8,5 ÷ 8,9

27

(0,95)

 

 

 

1/8”

9,7 ÷ 9,9

8,2 ÷ 8,6

 

1,5

 

M10x1,5

 

 

9,7 ÷ 9,9

8,7 ÷ 9,1

 

1

 

M10x1

 

 

10,9 ÷ 11,1

9,7 ÷ 10

20

(1,27)

 

 

7/16”-20

 

11,6 ÷ 11,9

10,2 ÷ 10,6

 

1,5

 

M12x1,5

 

 

12,4 ÷ 12,7

11,3 ÷ 11,6

20

(1,27)

 

 

1/2”-20

 

12,9 ÷ 13,1

11,4 ÷ 11,9

19

(1,34)

1/4

 

 

 

12,9 ÷ 13,1

11,4 ÷ 11,9

18

(1,41)

 

 

 

1/4”

13,6 ÷ 13,9

12,2 ÷ 12,6

 

1,5

 

M14x1,5

 

 

14 ÷ 14,3

12,7 ÷ 13

18

(1,41)

 

 

9/16”-18

 

15,5 ÷ 15,8

14,4 ÷ 14,7

18

(1,41)

 

 

5/8”-18

 

15,6 ÷ 15,9

14,2 ÷ 14,6

 

1,5

 

M16x1,5

 

 

16,3 ÷ 16,6

14,9 ÷ 15,4

19

(1,34)

3/8

 

 

 

16,3 ÷ 16,6

14,9 ÷ 15,4

18

(1,41)

 

 

 

3/8”

17,1 ÷ 17,4

15,8 ÷ 16,1

16

(1,59)

 

 

11/16”-16

 

17,6 ÷ 17,9

16,2 ÷ 16,6

 

1,5

 

M18x1,5

 

 

18,7 ÷ 19

17,3 ÷ 17,6

16

(1,59)

 

 

3/4”-16

 

19,6 ÷ 19,9

18,2 ÷ 18,6

 

1,5

 

M20x1,5

 

 

20,3 ÷ 20,6

18,9 ÷ 19,3

16

(1,59)

 

 

13/16”-16

 

20,5 ÷ 20,9

18,6 ÷ 19

14

(1,81)

1/2

 

 

 

20,7 ÷ 21,1

18,3 ÷ 18,7

14

(1,81)

 

 

 

1/2”

21,6 ÷ 21,9

20,2 ÷ 20,6

 

1,5

 

M22x1,5

 

 

22 ÷ 22,2

20,2 ÷ 20,5

14

(1,81)

 

 

7/8”-14

 

22,6 ÷ 22,9

20,6 ÷ 21

14

(1,81)

5/8

 

 

 

23,6 ÷ 23,9

22,2 ÷ 22,6

 

1,5

 

M24x1,5

 

 

25,1 ÷ 25,4

23,4 ÷ 23,8

14

(1,81)

 

 

1”-14

 

25,6 ÷ 25,9

24,2 ÷ 24,6

 

1,5

 

M26x1,5

 

 

26,1 ÷ 26,4

24,1 ÷ 24,5

14

(1,81)

 

 

 

 

26,3 ÷ 26,7

23,7 ÷ 24,1

14

(1,81)

3/4

 

 

3/4”

26,6 ÷ 26,9

24,3 ÷ -24,7

12

2,12

 

 

1.1/16”-12

 

26,6 ÷ 26,9

24,6 ÷ 25

 

2,12

 

M27x2

 

 

26,6 ÷ 26,9

25,2 ÷ 25,6

 

2

 

M27x1,5

 

 

27,6 ÷ 27,9

26,2 ÷ 26,6

 

1,5

 

M28x1,5

 

 

29,6 ÷ 29,9

27,4 ÷ 27,8

 

1,5

 

M30x2

 

 

29,6 ÷ 29,9

28,2 ÷ 28,6

 

2

 

M30x1,5

 

 

29,8 ÷ 30,1

27,6 ÷ 27,9

12

(2,12)

 

 

1.3/16”-12

 

29,8 ÷ 30,2

27,8 ÷ 28,1

14

(1,81)

7/8

 

 

 

32,6 ÷ 32,9

30,5 ÷ 30,9

 

2

 

M33x2

 

 

32,6 ÷ 32,9

31,2 ÷ 31,6

 

1,5

 

M33x1,5

 

 

33 ÷ 33,2

30,3 ÷ 30,8

11

(2,31)

1

 

 

 

33 ÷ 33,3

30,8 ÷ 31,2

12

(2,12)

 

 

1.5/16”-12

 

32,9 ÷ 33,4

30,3 ÷ 30,8

11,5

(2,21)

 

 

 

1”

35,6 ÷ 35,9

33,4 ÷ 33,8

 

2

 

M36x2

 

 

36,2 ÷ 36,5

34,3 ÷ 34,7

12

(2,12)

 

 

1.7/16”-12

 

37,6 ÷ 37,9

34,8 ÷ 35,1

11

(2,31)

1.1/8

 

 

 

37,6 ÷ 37,9

36,2 ÷ 36,6

 

1,5

 

M38x1,5

 

 

40,9 ÷ 41,2

38,7 ÷ 39,1

12

(2,12)

 

 

1.5/8”-12

 

41,6 ÷ 41,9

39,4 ÷ 39,8

 

2

 

M42x2

 

 

41,5 ÷ 41,9

39 ÷ 39,5

11

(2,31)

1.1/4

 

 

 

41,4 ÷ 42

39,2 ÷ 39,6

11,5

(2,21)

 

 

 

1. 1/4”

42,5 ÷ 42,8

40,6 ÷ 41

 

(2,12)

 

 

1.11/16”-12

 

44,6 ÷ 44,9

42,4 ÷ 42,8

 

2

 

M45x2

 

 

44,6 ÷ 44,9

43,2 ÷ 43,6

 

1,5

 

M45x1,5

 

 

47,3 ÷ 47,6

45,1 ÷ 45,5

12

(2,12)

 

 

1.7/8”-12

 

47,4 ÷ 47,8

44,8 ÷ 45,3

11

(2,31)

1.1/2

 

 

 

47,3 ÷ 47,9

45,1 ÷ 45,5

11,5

(2,21)

 

 

 

1. 1/2”

50,5 ÷ 50,8

48,6 ÷ 49

12

(2,12)

 

 

2”-12

 

51,6 ÷ 51,9

49,4 ÷ 49,6

 

2

 

M52x2

 

 

51,6 ÷ 51,9

50,2 ÷ 50,6

 

1,5

 

M52x1,5

 

 

59,4 ÷ 59,8

56,5 ÷ 56,8

11

(2,31)

2

 

 

 

59,9 ÷ 60,2

56,4 ÷ 56,7

11,5

(2,21)

 

 

 

2”

63,3 ÷ 63,6

61,3 ÷ 61,8

12

(2,12)

 

 

2. 1/2”-12

 

64,6 ÷ 64,9

62,6 ÷ 63

 

2

 

M65x2

 

 

65,4 ÷ 65,7

62,7 ÷ 63

11

(2,31)

2.1/4

 

 

 

72,7 ÷ 73

68,8 ÷ 69,1

8

(3,175)

 

 

 

2. 1/2”

74,9 ÷ 75,2

72,2 ÷ 72,5

11

(2,31)

2.1/2

 

 

 

87,5 ÷ 87,9

84,9 ÷ 85,3

11

(2,31)

3

 

 

 

88,5 ÷ 88,9

84,7 ÷ 85,1

8

(3,175)

 

 

 

3”

112,6 ÷ 113

110,1 ÷ 110,5

11

(2,31)

4

 

 

 

113,9 ÷ 114,3

110,2 ÷ 110,6

8

(3,175)

 

 

 

4”

129,4 ÷ 129,8

123,2 ÷ 124

 

6

 

M130x6

 

 

138 ÷ 138,4

135,5 ÷ 135,9

11

(2,31)

5

 

 

 

139,4 ÷ 139,7

127,5 ÷ 127,9

 

9,7

 

 

5. 1/2”- (DIN 11)

 

139,8 ÷ 141,3

 

8

(3,175)

 

 

 

5”

163,4 ÷ 163,8

160,9 ÷ 161,4

11

(2,31)

6

 

 

 

167,8 ÷ 168,3

 

8

(3,175)

 

 

 

6”

218,5 ÷ 219

 

8

(3,175)

 

 

 

8”

Threads, which are screw cuts on a cylindrical or conical face, inside or outside. Among them, metric threads and pipe threads can be distinguished. They belong to triangular threads, depending on the needs, they can be divided into fine, coarse, normal, right or left threads. The mechanics of the thread are the same as the mechanics of the incline, and therefore threaded connections can be classified as simple machines.

The screw mechanism allows us to multiply the applied force. We apply a force in the form of a rotary motion and we obtain a much greater longitudinal force, much like an inclined plane. In addition to the connecting function, the use of a screw is also used in elements such as drives for presses, machine tools or lifts.

Threaded connections are detachable connections where the connecting element is a bolt, screw or nut. Additionally, threaded connections may contain elements such as washers or split pins. Regardless of the type and nature of the threaded connection, the most important issue is to guarantee a high pressing force, which will ensure a durable and safe connection, as well as trouble-free disassembly. Each threaded connection should be selected to withstand the loads to which it was applied.

The strength of threaded connections depends on many factors.

Some of them cause corrosion processes, others destabilize the connection. Additionally, factors such as:

  • large fluctuations and extreme temperatures
  • influence of weather conditions
  • aggressive environment (chemicals)

Inch thread table

In the metric system, threads that are multiples of a millimeter are used, such as M5, M6, M7, etc. The second important criterion is the thread pitch. All these features of metric threads have been standardized. In order to be able to easily and clearly select the thread size, please refer to the standardized metric thread table.

However, there are areas such as gas, hydraulics and pneumatics where inch connections are dominant.

Cylindrical "G" threads and Whitworth "W" threads are most commonly used.

Common inch threads

BSP - British Standard Pipe thread, Whitworth pipe thread

This group of threads is standard in many countries except the United States. This type of thread is characterized by a V-groove with a 55 ° slope and a rounded crest.

There are two types of BSP threads, namely:

  • cylindrical BSPP, where both the male and female sides are parallel to each other.

Connections of this type are used in countries such as Great Britain, Australia, or in Europe and Asia. These types of threaded connections require additional sealing in the form of, for example, Teflon tape.

  • tapered BSPT, where the external threads get tighter and the internal threads are most often parallel.

Conical threads seal on the cone and therefore do not require additional seals.

Thread tightness acc. To ISO standards

  • ISO 228 - pipe threads where no additional seals are required
  • ISO 7 - pipe threads where seals are required

BSP thread types and standards (letter designation)

  • G - parallel BSPP internal and external thread, cylindrical acc. To ISO 228
  • R - BSPT conical male thread acc. To ISO 7
  • Rp - BSPT parallel female thread acc. To ISO 7
  • Rc - BSPT internal thread acc. To ISO 7

Briggs NPT / NPS pipe thread

NP - or National Thread Pipe, a V-shaped pipe thread with a slope angle of 60 ° with a flattened crest, very popular in Canada and the United States.

There are two types of NP threads, namely:

  • NPS - thread where the male and female parts of the thread are parallel (straight thread), which results in a lack of sealing.
  • NPT - conical thread that gives us a seal on the thread (more popular than NPS)

BSP and NPT threads do not match and do not connect between them.

Metric threads acc. ISO standards

V-shaped thread with a slope of 60 °, the outer and inner parts are parallel to each other.

These threads have different sizes of the thread pitch for a given diameter, i.e. we can distinguish the usual thread pitch and the so-called thread. fine-threaded.

Standard metric threads have a default pitch size, and are selected only by diameter, e.g. M12

Fine threads have smaller pitches, and are not as popular as regular metric threads.

They are recognized by the diameter and the size of the scale , i.e. pitch, which means that for a given diameter they are available in two sizes of the scale (pitch)

Dimensions of inch BSP threads

Thread Size [inch]

Number of turns per inch

Thread Pitch in [mm]

Outer Diameter [mm]

Inner Diameter [mm]

Measuring Length in [mm]

1/8

28

0.907

9,728

8.565

3.97

1/4

19

1.337

13.157

11,445

6.012

3/8

19

1.337

16,662

14.95

6.35

1/2

14

1.814

20,955

18,633

8.164

3/4

14

1.814

26,441

24.12

9.525

1

11

2.309

33.249

30.292

10,391

1 1/4

11

2.309

41.91

38,953

12.7

1 1/2

11

2.309

47,803

44,846

12.7

2

11

2.309

59,614

56,657

15,875

2 1/2

11

2.309

75.184

72.227

17,463

3

11

2.309

87,884

84,927

20,638

4

11

2.309

113.03

110.073

NPT thread sizes

Thread Size [inch]

Number of turns per inch

Thread Pitch [mm]

Outer Diameter [mm]

1/8

27

0.94082

10.29

3/8

18

1.41122

13.72

1/2

18

1.41122

17.15

3/4

14

1.81432

21.34

1

14

1.81432

26.67

1 1/4

11 1/2

2.20878

33.4

1 1/2

11 1/2

2.20878

42.16

2

11 1/2

2.20878

48.26

2 1/2

11 1/2

2.20878

60.33

3

8

3.175

73.03

4

8

3.175

88.9

4

8

3.175

114.3

Compare NPT / NPS Threads to BSP Threads

Thread Size [inch]

Number of turns per inch
NPT / NPS

Number of turns per inch
BSP

1/4

18

19

1/8

27

28

3/8

18

19

1/2

14

14

3/4

14

14

1

11 1/2

11

1 1/4

11 1/2

11

1 1/2

11 1/2

11

2

11 1/2

11

2 1/2

8

11

3

8

11

3 1/2

8

11

4

8

11

5

8

11

6

8

11