System

Minimum inner diameter    mm

Outer diameter  mm

Pitch mm

Unit length m

Compatible steel tube

Metric System

British System

Thin steel 

Thick steel

φ6

5.7

8.2

2.7

100

φ8

5/16"

7.7

11

4

100

φ10

1/4"

9.7

13.5

4.7

100

#12

1/2"

φ12

3/8"

11.7

15.6

4.7

100

#15

5/8"

#10

3/8"

φ15

1/2"

14.7

19

5.7

100

#20

3/4"

#15

1/2"

φ20

3/4"

19.6

24.3

6.4

50

#25

1"

#20

3/4"

φ25

1"

24.5

30.3

8.7

50

#32

1/1/4"

#25

1"

φ32

1/1/4"

31.5

38

10.5

25

#40

1/1/2"

#32

1/1/4"

φ38

1/1/2"

37.5

45

11.4

25

#50

2"

#40

1/1/2"

φ51

2"

49.5

58

11.4

20

#70

2/1/2"

#50

2"

φ64

2/1/2"

62.5

72.5

14.2

10

#80

3"

#70

2/1/2"

φ75

3"

73

83.5

14.2

10

#80

3"

φ100

4"

97

108.5

14.2

10

#100

4"

φ125

5’

122

133.5

14.2

5

#125

5"

φ150

6’

146

158.5

14.2

5

#150

6