Tap drill, major and minor diameters, thread height and hand-tight engagement length for NPT pipe threads from 1/8 to 4 inch, per ASME B1.20.1. Enter the nominal pipe size.
Complete reference tables and engineering data for npt pipe thread. All values verified against ISO, ANSI, and manufacturer standards.
National Pipe Taper (NPT) threads are the standard tapered pipe thread used in North America for pressure-tight joints. The taper creates an interference fit that seals the connection, typically assisted by thread sealant or PTFE tape.
NPTF (National Pipe Taper Fuel, also called Dryseal) has tighter tolerances and is designed to seal without sealant by metal-to-metal crest-root contact. NPT requires thread sealant or PTFE tape. Both use the same taper and thread form.
Standard engagement for hand-tight NPT is L1 (wrench make-up length). For power-tight assembly, use L3 length. The fitting should protrude 3-4 threads beyond the face of the mating part after proper tightening.
Yes. Program a tapered toolpath (1:16 taper) with a 60° thread insert. Use a G76 or G92 threading cycle with the taper angle option. Single-point threading of NPT requires precise taper control for proper sealing.
This reference provides standard NPT thread dimensions per ASME B1.20.1. For accurate thread machining, program a 1:16 taper toolpath and use a dedicated 60° full-profile NPT threading insert.
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WORKING WITH NPT THREADS? Pipe threads are the family most often supplied to the wrong taper standard. See how we specify and inspect pipe thread tooling.
Pipe threads are taper threads, so the tap depth and the gauge decide whether the joint seals. Send the standard, size and whether the joint is for fluid or gas.