British standard pipe thread

The British Standard Pipe thread (BSP thread) is a family of standard screw thread types that has been adopted internationally for interconnecting and sealing pipe ends by mating an external (male) with an internal (female) thread.

Contents

Types

Two types of threads are distinguished:

These can be combined into two types of joints:

Thread form

Pipe thread sizes

A list of 16 thread sizes are defined by the standards, ranging from 116 to 6. The size number was originally based on the inner diameter measured in inches of a steel tube for which the thread was intended, but in the modern metric version of the standard is simply a size number.

Dash
thread
size
Thread
size
Threads
/ in
Pitch
(mm)
Thread major
diameter
A/F (mm) Gauge length
(mm)
Corresponding pipe Tapping drill
size (mm)
(mm) (in) DN OD
(mm)
OD
(in)
Thickness
(mm)
BSP.PL (Rp) BSP.F (G)
0.0625 28 0.907 7.723 0.304 4 6.60 6.80
−2 0.125 28 0.907 9.728 0.383 15 4 6 10.2 0.40 2 8.60 8.80
−4 0.25 19 1.337 13.157 0.518 19 6 8 13.5 0.53 2.3 11.50 11.80
−6 0.375 19 1.337 16.662 0.656 22/23 6.4 10 17.2 0.68 2.3 15.00 15.25
−8 0.5 14 1.814 20.955 0.825 27 8.2 15 21.3 0.84 2.6 18.75 19.00
−10 0.625 14 1.814 22.911 0.902 16 2.6 - 21.00
−12 0.75 14 1.814 26.441 1.041 32 9.5 20 26.9 1.06 2.6 24.25 24.50
−16 1 11 2.309 33.249 1.309 43 10.4 25 33.7 1.33 3.2 30.40 30.75
−20 1.25 11 2.309 41.910 1.650 53 12.7 32 42.4 1.67 3.2 39.00 39.50
−24 1.5 11 2.309 47.803 1.882 57 12.7 40 48.3 1.90 3.2 45.00 45.00
−32 2 11 2.309 59.614 2.347 70 15.9 50 60.3 2.37 3.6 56.75 57.00
2.5 11 2.309 75.184 2.960 17.5 65 76.1 3.00 3.6
3 11 2.309 87.884 3.460 20.6 80 88.9 3.50 4
4 11 2.309 113.030 4.450 25.5 100 114.3 4.50 4.5
5 11 2.309 138.430 5.450 28.6 125 139.7 5.50 5
6 11 2.309 163.830 6.450 28.6 150 165.1 6.50 5

The major diameter listed is the outer diameter of the external thread. For a taper thread, it is the diameter at the "gauge length" from the small end of the thread. The taper is 1 to 16, meaning that for each 16 units of measurement increase in the distance from the end, the diameter increases by 1 unit of measurement.

Pipe thread designations

These standard pipe threads are formally referred to by the following sequence of blocks:

Threads are normally right-hand. For left-hand threads, the letters "LH" are appended.

Example: Pipe thread EN 10226 Rp 2½

The terminology for the use of G and R originated from Germany (G for gas, as it was originally designed for use on gas pipes; R for rohr (meaning pipe).)

See also

References

External links