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British Standard Pipe thread (G)

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

 

 

The thread form follows the British Standard Whitworth standard:

1.) Symmetrical V-thread in which the angle between the flanks is 55° (measured in an axial plane)

2.) One-sixth of this sharp V is truncated at the top and the bottom

3.) The threads are rounded equally at crests and roots by circular arcs ending tangentially with the flanks where r ≈ 0.1373P

4.) The theoretical depth of the thread is therefore 0.6403 times the nominal pitch h ≈ 0.6403P

 

 

  Thread size (inch)     TPI     Major diameter (mm)     Minor diameter (mm)  
G 1/16" 28 7.72 6.56
G 1/8" 28 9.73 8.57
G 1/4" 19 13.16 11.45
G 3/8" 19 16.66 14.95
G 1/2" 14 20.96 18.63
G 5/8" 14 22.91 18.63
G 3/4" 14 26.44 20.59
G 7/8" 14 30.20 27.88
G 1" 11 33.25 30.29
G 1-1/8" 11 37.90 34.94
G 1-1/4" 11 41.91 38.95
G 1-3/8" 11 44.32 41.37
G 1-1/2" 11 47.80 44.85
G 1-5/8" 11 52.88 49.93
G 1-3/4" 11 53.75 50.79
G 1-7/8" 11 57.00 54.04
 G 2" 11 59.61 56.66

BSPP G British Standard Pipe Parallel assembly

*Ref: Learn more about British Standard Pipe

 

British Standard Pipe Taper thread (R)

Taper threads, British Standard Pipe Taper thread (BSPT), whose diameter increases or decreases along the length of the thread; denoted by the letter R. The taper is 1:16, meaning that for each 16 units of measurement increase in the distance from the end, the diameter increases by 1 unit of measurement.

 

 

The thread form follows the British Standard Whitworth standard:

1.) Symmetrical V-thread in which the angle between the flanks is 55° (measured in an axial plane)

2.) One-sixth of this sharp V is truncated at the top and the bottom

3.) The threads are rounded equally at crests and roots by circular arcs ending tangentially with the flanks where r ≈ 0.1373P

4.) The theoretical depth of the thread is therefore 0.6403 times the nominal pitch h ≈ 0.6403P

 

 

  Male Thread size (inch)     Female Thread size (inch)     TPI     Major diameter (mm)     Minor diameter (mm)  
R 1/16" Rp 1/16" 28 7.72 6.56
R 1/8" Rp 1/8" 28 9.73 8.57
R 1/4" Rp 1/4" 19 13.16 11.45
R 3/8" Rp 3/8" 19 16.66 14.95
R 1/2" Rp 1/2" 14 20.96 18.63
R 5/8" Rp 5/8" 14 22.91 18.63
R 3/4" Rp 3/4" 14 26.44 20.59
R 7/8" Rp 7/8" 14 30.20 27.88
R 1" Rp 1" 11 33.25 30.29
R 1-1/8" Rp 1-1/8" 11 37.90 34.94
R 1-1/4" Rp 1-1/4" 11 41.91 38.95
R 1-3/8" Rp 1-3/8" 11 44.32 41.37
R 1-1/2" Rp 1-1/2" 11 47.80 44.85
R 1-5/8" Rp 1-5/8" 11 52.88 49.93
R 1-3/4" Rp 1-3/4" 11 53.75 50.79
R 1-7/8" Rp 1-7/8" 11 57.00 54.04
 R 2"  Rp 2" 11 59.61 56.66

BSPT R Rc British Standard Pipe Taper thread assembly