Whitworth Pipe Thread for pipes and fittings. Parallel female thread and tapered male thread (taper 1 : 16).
An appropriate sealing compound can be used in the thread to ensure a leak-proof joint.
The flank angle is 55°.
TPI – Pitch – Tap
Maj./Min. Diameter
Male Thread Dia. Pitch mm TPI Tap/Drill mm
R 1/16” 6.561 28 0.907
R 1/8” 8.566 28 0.907
R 1/4” 11.445 19 1.337
R 3/8” 14.95 19 1.337
R 1/2” 18.631 14 1.814
R 3/4” 24.117 14 1.814
R 1” 30.291 11 2.309
R 1 1/4” 38.952 11 2.309
R 1 1/2” 44.845 11 2.309
R 2” 56.656 11 2.309
R 2 1/2” 72.226 11 2.309
R 3” 84.926 11 2.309
R 4” 110.072 11 2.309
R 5” 135.472 11 2.309
R 6” 160.872 11 2.309
Male Thread Dia. Female Thread Dia. Maj. Dia. mm Min. Dia. mm
R 1/16” Rp 1/16” 3 7.723
R 1/8” Rp 1/8” 6 9.728
R 1/4” Rp 1/4” 8 13.157
R 3/8” Rp 3/8” 10 16.662
R 1/2” Rp 1/2” 15 20.955
R 3/4” Rp 3/4” 20 26.441
R 1” Rp 1” 25 33.249
R 1 1/4” Rp 1 1/4” 32 41.91
R 1 1/2” Rp 1 1/2” 40 47.803
R 2” Rp 2” 50 59.614
R 2 1/2” Rp 2 1/2” 65 75.184
R 3” Rp 3” 80 87.884
R 4” Rp 4” 100 113.03
R 5” Rp 5” 125 138.43
R 6” Rp 6” 150 163.83