NPT Tap Drill Sizes When tapping NPT threads, the drill size determines the minor diameter of the internal thread. Because NPT threads are tapered, the drill creates a straight hole that the tapered tap gradually engages — you’ll get full threads near the entrance and partial threads at depth. NPT Size TPI Tap Drill (in) … Read more
What is NPT? NPT (National Pipe Thread) is the US standard for tapered pipe threads. The taper is 1°47′ (3/4 inch per foot), which means the threads wedge tighter as you screw them together — creating a seal. NPT threads require thread sealant (Teflon tape or pipe dope) for a leak-free connection. NPT vs. NPTF: … Read more
NPS Pipe Dimensions NPS (Nominal Pipe Size) is the North American standard for pipe sizing. Like NPT threads, the “nominal” size doesn’t match the actual dimensions — it’s a naming convention that’s been around for over a century. The OD is constant for a given NPS size. The schedule (40, 80, etc.) determines wall thickness … Read more