Whitworth Pipe Threads

Whitworth Pipe Threads differ in sealing on the thread (acc. ISO 7/1 and DIN EN 10226) and not sealing
on the thread (ISO 228).

Comparison of different Whitworth Pipe Threads


G (BSP) Rp Rc R
Standard ISO 228 Part 1 ISO 7/1
DIN EN 10226/1
ISO 7/1
DIN EN 10226/2
ISO 7/1
DIN EN 102261+ 2
Kind of Connection not sealing on the thread sealing on the thread sealing on the thread sealing on the thread
Internal Thread cylindrical cylindrical taper (1:16) Rp or Rc
External Thread cylindrical R (taper) R (taper) taper (1:16)


G (BSP)
British Standard Pipe DIN ISO 228
Cylindrical Britisch Standard Pipe Thread - not sealing on the thread

G (BSP) Major Diameter
Inch
Major Diameter
mm
TPI Pitch P
mm
G 1/8" 0,383 9,730 28 0,907
G 1/4" 0,518 13,160 19 1,337
G 3/8" 0,656 16,660 19 1,337
G 1/2" 0,825 20,950 14 1,814
G 5/8" 0,902 22,910 14 1,814
G 3/4" 1,041 26,440 14 1,814
G 7/8" 1,189 30,200 14 1,814
G 1" 1,309 33,250 11 2,309
G 1 1/8" 1,492 37,900 11 2,309
G 1 1/4" 1,650 41,910 11 2,309
G 1 3/8" 1,745 44,320 11 2,309
G 1 1/2" 1,882 47,800 11 2,309
G 1 3/4" 2,116 53,740 11 2,309
G 2" 2,347 59,610 11 2,309
G 2 1/4" 2,587 65,710 11 2,309
G 2 1/2" 2,960 75,180 11 2,309
G 2 3/4" 3,210 81,530 11 2,309
G 3" 3,460 87,880 11 2,309
G 3 1/4" 3,700 93,980 11 2,309
G 3 1/2" 3,950 100,330 11 2,309
G 3 3/4" 4,200 106,680 11 2,309
G 4" 4,450 113,030 11 2,309

Please note:
The Major Diameter of 1" Inch Pipe Thread is 33,25 mm or 1,309 Inches (not 25,4 mm)!
Historically it had it's origin from the manufacture of steel pipes in the beginning of the 20th century. In that time the normal
1" Inch pipes with the internal diameter of 1" Inch had a outside diameter of 1.309 Inches (about 33 mm).




The diameter and pitches (Threads per Inch) are all the same in G (BSP), Rp, Rc and R thread.
The differences are G(BSP) is cylindrical and not sealing on the thread, Rp is cylindrical and sealing on the
thread. Rc is taper and sealing on the thread. The suitable external thread to Rp and Rc is the R thread.
R Thread is taper and sealing on the thread. Rp, Rc and R differ in tolerances to G (BSP).

G (BSP) P
TPI
p
[mm]
Out.-Ø
d = D
Pitch-Ø
d2 = D2
Minor-Ø
d1 = D1
Rp / Rc
R
a
[mm]
Tolerances of internal thread
pitch-Ø            turns
[mm]                     
Tolerances of
external thread
turns         mm
1/16 28 0,907 7,723 7,142 6,561 1/16 4 ± 0,071 ± 1.1/4 ± 1 ± 0,9
1/8 28 0,907 9,23 9,147 8,566 1/8 4 ± 0,071 ± 1.1/4 ± 1 ± 0,9
1/4 19 1,337 13,157 12,301 11,445 1/4 6 ± 0,104 ± 1.1/4 ± 1 ± 1,3
3/8 19 1,337 16,662 15,806 14,950 3/8 6,4 ± 0,104 ± 1.1/4 ± 1 ± 1,3
1/2 14 1,814 20,955 19,793 18,631 1/2 8,2 ± 0,142 ± 1.1/4 ± 1 ± 1,8
5/8 14 1,814 22,911 21,749 20,587





3/4 14 1,814 26,441 25,279 24,117 3/4 9,5 ± 0,142 ± 1.1/4 ± 1 ± 1,8
7/8 14 1,814 30,201 29,039 27,877





1 11 2,309 33,249 31,770 30,291 1 10,4 ± 0,18 ± 1.1/4 ± 1 ± 2,3
1.1/8 11 2,309 37,897 36,418 34,939





1.1/4 11 2,309 41,910 40,431 38,952 1.1/4 12,7 ± 0,18 ± 1.1/4 ± 1 ± 2,3
1.1/2 11 2,309 47,803 46,324 44,845 1.1/2 12,7 ± 0,18 ± 1.1/4 ± 1 ± 2,3
1.3/4 11 2,309 53,746 52,267 50,788





2 11 2,309 59,614 58,135 56,656 2 15,9 ± 0,18 ± 1.1/4 ± 1 ± 2,3
2.1/4 11 2,309 65,710 64,231 62,752





2.1/2 11 2,309 75,184 73,705 72,226 2.1/2 17,5 ± 0,216 ± 1.1/2 ± 1.1/2 ± 3,5
2.3/4 11 2,309 81,534 80,055 78,576





3 11 2,309 87,884 86,405 84,926 3 20,6 ± 0,216 ± 1.1/2 ± 1.1/2 ± 3,5
3.1/2 11 2,309 100,300 98,851 97,372





4 11 2,309 113,030 111,551 110,072 4 25,4 ± 0,216 ± 1.1/2 ± 1.1/2 ± 3,5



Internal Thread Rp (cylindrical) and External Thread R (taper) - sealing on the thread


R

 

 

Internal Thread Rc (taper) and External Thread R (taper) - sealing on the thread



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