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G Thread ring gauge have class A and class B, What about G thread plug gage? still have A and B class?
Source: | Author:China G threa plug and thread ring gages | Published time: 417 days ago | 339 Views | Share:
G Thread ring gauge have class A and class B, What about G thread plug gage? still have A and B class?

G Thread ring gauge have class A and class B, What about G thread plug gage? still have A and B class?

and we found that many Chinese thread gauges still make Class TB thread plugs, what is standard ,and what is mean of TB ?

China made G thread plug gauges with calibration reports

As you know the G thread ring gauges and G thread plug gages are all British Standard Pipe Parallel ISO-228


The ISO 228 "Pipe Threads where Pressure-tight Joints are not made on the Threads" consists of the following parts:

  • ISO 228-1:2000 Dimensions, tolerances and  designation

  • ISO 228-2:1987 Verification by means of limit  gauges

 The following are the size of G thread  per ISO 228-1

G Size
   (in)

Major (Outside)    Diameter (mm)
   
   

Minor (Nut)    Diameter
   (mm)
   
   

Core Hole    Diameter
   (mm)
   
   

Thread Count
   (TPI)

Thread Pitch
   (mm)








G 1/8

9.73

8.85

8.80

28

0.907


G 1/4

13.16

11.89

11.80

19

1.337








G 3/8

16.66

15.39

15.25

19

1.337








G 1/2

20.95

19.17

19.00

14

1.814








G 5/8

22.91

21.13

21.00

14

1.814








G 3/4

26.44

24.66

24.50

14

1.814








G 7/8

30.20

28.42

28.25

14

1.814








G 1

33.25

30.93

30.75

11

2.309








G 1 1/8

37.90

35.58

35.30

11

2.309








G 1 1/4

41.91

39.59

39.25

11

2.309








G 1 3/8

44.32

42.00

41.70

11

2.309








G 1 1/2

47.80

45.48

45.25

11

2.309








G 1 3/4

53.74

51.43

51.10

11

2.309








G 2

59.61

57.29

57.00

11

2.309








G 2 1/4

65.71

63.39

63.10

11

2.309








G 2 1/2

75.18

72.86

72.60

11

2.309








G 2 3/4

81.53

79.21

78.90

11

2.309








G 3

87.88

85.56

85.30

11

2.309








G 3 1/4

93.98

91.66

91.50

11

2.309








G 3 1/2

100.33

98.01

97.70

11

2.309








G 3 3/4

106.68

104.30

104.00

11

2.309








G 4

113.03

110.71

110.40

11

2.309








  • TPI stands for Threads Per Inch and is a count of      the mumber of threads per inch. TPI is used for American fasteners.

  • Thread pitch is the distance between the threads      and is used for metric fasteners.

  • G-threads have a parallel shape in accordance      with the DIN-EN-ISO 228-1 standard with flank angle 55o.


Example - Typical designation for Thread according ISO 228

  • ISO 228 G 3 1/4"

Chinese G thread ring gauges PER ISO 228-2

Now ,let us look into the class TB thread plug gages, we found that they are made according the old China G thread standard, it didn't contronl the Max diameterof  size per ISO 228. It is too small than iso 228-2 , they only control the pitch diameter.


  • G/R/Rp - Whitworth Pipe Threads (BSPP/BSPT)

  • ISO 7-1      Pressure Tight Thread Joints


      Sowant Precision Gage co.,ltd is famous thread gauge manufactory in China, we can offer you G thread Plugs and G thread ring gauges per ISO 228-2 standard, we also can offer you the API thread gages,API 5B,API 7-2, API 11B and ASME B1.5 standard Acme thread gauges  and ASME B1.8 Stub acme thread ring gauges.include UN thread gauges. if you need the price ,please contact us.