55degree Whitworth Thread Form. Whitworth Pipe Threads are used almost exclusively by countries which are otherwise on the metric system 3/8: 19: 0.656: 15.25 mm 14.75mm: 19/32" 37/64" 1/2: 14: 0.825: 19.00mm: 18.25mm 3/4" 23/32" 5/8: 14: 0.902: 21 mm 53/64" 3/4: 14: dimensions, and part numbers are subject to change without noticeAwesome thanks for the reply. I certainly understand the math behind it, but I'm still unsure of the starting point for my taper. Say I've got .560 hole thru 2 inches, 3/8 npt nearside, I can't start the taper at the far side of the two inches depth. The hole would be much too large at the nearside. OfPipe D. Technical Bulletin, #16 NPT Taper Pipe Thread Gages, defines the L-1 basic hand tight engagement on NPT product threads. This same L-1 length applies to NPTF threads. It is the theoretical length of assembly (hand-tight) if both parts had perfect thread form and taper and were exactly at the nominal size.
Jumpto: Step 1 (Thread Identification) > Step 2 (Sealing Forms) >Step 3 (Dash Sizes) Step 3: Dash Sizes. Use the information from the previous step to locate the Dash Size in the Thread Guide below. Click Here to Download this Table as a PDF
NationalPipe Threads (NPT) profile, dimension and tolerance. NPT 1/8, NPT 1/4, NPT 3/8, NPT 1/2, NPT 3/4, NPT 1, NPT 1 1/4, NPT 1 1/2, NPT 2, NPT 2 1/2, NPT 3, NPT 3 1/2, J03W. 496 52 159 454 136 424 460 476 358