British Standard Pipe Threads (BSPP, BSPF)

Dash Size

Nominal Thread Size - t.p.i. Basic depth of thread (h) (in.) Basic Major Dia. (in.) Basic effective Dia. (in.) Basic Minor Dia. (in.) Recommended tap drill size
size Rp (mm) Size G (mm)
-1 1/16-28 .0229 .304 .2812 .2583 6.60 6.80

-2

1/8-28 .0229 .383 .3601 .3372 8.60 8.80
-4 1/4-19 .0337 .518 .4843 .4506 11.50 11.80
-6 3/8-19 .0337 .656 .6223 .5886 15.00 15.25
-8 1/2-14 .0457 .825 .7793 .7336 18.50 19.00
-10 5/8-14 .0457 .902 .8563 .8106 - 21.00
-12 3/4-14 .0457 1.041 .9953 .9496 24.00 24.50
-14 7/8-14 .0457 1.189 1.1433 1.0976 - 23.25
-16 1-11 .0582 1.309 1.2508 1.1926 30.25 30.75
-20 1 1/4-11 .0582 1.650 1.5918 1.5336 39.00 39.50
-24 1 1/2-11 .0582 1.882 1.8238 1.7656 45.00 45.00
-28 1 3/4-11 .0582 2.116 2.0578 1.9996 - 51.00
-32 2-11 .0582 2.347 2.2888 2.2306 56.50 57.00
-36 2 1/4-11 .0582 2.587 2.5288 2.4706 No Sizes of B.S. (British Standard) drills are recommended in B.S. 1157:1975 for this range
-40 2 1/2-11 .0582 2.960 2.9018 2.8436
-44 2 3/4-11 .0582 3.210 3.1518 3.0936
-48 3-11 .0582 3.460 3.4018 3.3436
-52 3 1/4-11 .0582 3.700 3.6418 3.5836
-56 3 1/2-11 .0582 3.950 3.8918 3.8336
-60 3 3/4-11 .0582 4.200 4.1418 4.0836
-64 4-11 .0582 4.450 4.3918 4.3336
British Standard Pipe(BSPP, BSPF)
Thread Form

r = Basic Radius = * 137329 p

h = Basic Depth of Thread = *640327 p

p = Pitch = 1/t.p.i. (Threads per Inch)

ISO 228, DIN 259, BS2779, JIS B0202

In Japan this thread is known as (PF)

Use prefix G for parallel thread. Example: G1/2

Ref. Catalog Page 42 (Chart 2)

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