NominalSize BSPT Thread Form Type Major Diameter mm d=D Pitch mm p Threads per inch tpi Pitch Diameter mm d2=D2 Minor Diameter Male Thd. d3=D3 Thread Height H1 Rounding r Effective Thread Length mm External Tap Drill Diameter mm; R 1/16: 1/16" BSPT: 7.723: 0.907: 28: 7.142: 6.561: 0.581: 0.125: 2.5: BSW BSF BSPP BSPF BSPT
38 - 28 28-UN : Basic Thread Dimensions (Pitch, minor & major diameters, depth, lead), Tolerance range for all applicable classes and much more Dryseal Pipe Threads (NPTF) British Pipe Threads (BSP) ACME Trapezoidal Threads; Materials Menu Toggle. Tap Drill Sizes for 3/8 - 28 28-UN. If not specified, assume a thread depth of 75%.
HelicoilDrill Chart. The minimum drilling depths shown below allow for the following recommended practices: Countersinking the drilled hole to prevent a feather edge at the start of the tapped hole. 3/4 - 1-1/2 pitch of insert "set down" to allow for maximum production tolerance. Dimensions are shown for both plug and bottoming taps.
NPTNPTF (Dryseal) NPS (Straight) NPSF (Dryseal) Designation Pipe size O.D. TPI Tap drill size Decimal tap drill size Tap drill size Decimal tap drill size Tap drill size Decimal tap drill size Tap drill size Decimal tap drill size; 1/16 - 27.3125: 27: D: 0.2460: D: 0.2460: 1/4: 0.2500: 1/4: 0.250: 1/8 - 27: 405: 27: Q: 0.3320: R: 0.3390: 11/32
NPTthread to ANSI B1.20.2 Nominal size Ø D1 P Ø D2 Hole Ø D3 M6 x 1 6 1 5.2 6.0 + 0.2 M8 x 1 8 1 7.1 8.0 + 0.2 M10 x 1 10 1 9.1 10.0 + 0.2 NPT 1/4" 13.7 1.41 14.1 – 0.2 NPT 3/8" 17.1 1.41 17.4 – 0.2 NPT 1/2" 21.3 1.81 21.6 – 0.2 NPT 3/4" 26.7 1.81 27.0 – 0.2
. 244 17 322 222 16 433 115 94
3 8 npt thread drill size
