Guide to NPT Thread

Guide to NPT Thread

The threaded pipe can afford effective sealing when conveying liquid, gas, steam, and hydraulic fluid. These threads can be produced on different materials with CNC machining services and other techniques. One of the typical standard threads is NPT, you may have listened to 1/8 NPT thread as well as 1/2 NPT thread, what do they mean? Right here we’ll discuss what NPT stands for, the characteristics of the NPT threads and the fundamentals of NPT thread sizes, you can additionally examine out the NPT thread size table.

What is the NPT Thread?

What is NPT Thread

NPT stands for National Pipeline Thread, additionally known as American National Standard Pipeline thread, it is a U.S technical criterion for measuring screw threads on threaded pipelines as well as pipeline fittings. NPT threads can be divided right into tapered and straight thread series for various objectives. NPT is specified by ANSI/ASME common B1.20.1.

Characteristics of the NPT threads (National Pipe Thread Tapered):

  • The angle between the taper and the center axis of the pipeline ≈ 1.7899 ° ≈ 1 ° 47 ′ 24 ″.
  • The truncation of roots and crests are flat.
  • 60 ° thread angle.
  • Pitch is determined in threads per inch (TPI).

Pipeline threads can be designed to numerous kinds for matching both with or without thread sealants. For example, the National Standard Taper Pipe Thread permits them to develop a seal when tightened, the larger size keeps compressing right into a smaller diameter and also lastly develops a seal.

Kinds of NPT Threads

  • NPSI: National pipe straight-intermediate.
  • NPSL: National pipe straight-locknut.
  • NPSM: National pipeline straight-mechanical.
  • NPTF: National pipe taper-fuel.
  • NPTR: National pipeline taper-railing.
  • NPT: National pipe taper.
  • NPS: National pipeline straight.
  • NPSC: National pipe straight-coupling.
  • NPSF: National pipe straight-fuel.
  • NPSH: National pipeline straight-hose.

NPT threads can also be described as MPT (Male Pipeline Thread) or NPT (M) for exterior threads, and also FPT (Women Pipeline thread) or NPT (F) for inner threads. But MPT and FPT are not defined in the ANSI requirement.

NPT Thread Sizes

  • When figuring out a thread or recognizing size, the threads-per-inch and outdoors size of the thread are essential due to the fact that there is more than one size that has the same TPI. So the OD of a pipe or fitting should be determined and compared to a thread size table for recognition.
  • The taper price is 1 in 16 inches.
  •  NPT and also NPS threads are not interchangeable, NPT threads are tapered and also NPS threads are straight, but both NPT and NPS have the very same thread pitch, shape and also angle.
  • Example of NPT thread classification: 1/8– 27 NPT.
  • Frequently made use of NPT thread sizes including 1/8, 1/4, 3/8, 1/2, 3/4, 1, 1 +1/ 4, 1 +1/ 2, 2, 2 +1/ 2, 3, 4, 5, and also 6 inches, can be located on the majority of U.S pipes as well as installations. The thread sizes smaller sized than 1/8 inch as well as larger than 6 inches are occasionally utilized for certain functions.
  • The pipeline dimension in the NPT thread dimensions chart does not refer to any kind of physical measurements, it is made use of as a trade size.

NPT Thread Dimensions Table

Thread Size TPI Pitch Major Diameter(OD)
inch mm inch mm
1/8 27 0.03704 0.94082 0.405 10.29
1/4 18 0.05556 1.41122 0.54 13.72
3/8 18 0.05556 1.41122 0.675 17.15
1/2 14 0.07143 1.81432 0.84 21.34
3/4 14 0.07143 2.81432 1.05 26.67
1 11 1/2 0.08696 2.20878 1.315 33.4
1 1/4 11 1/2 0.08696 2.20878 1.66 42.16
1 1/2 11 1/2 0.08696 2.20878 1.9 48.26
2 11 1/2 0.08696 2.20878 2.375 60.33
2 1/2 8 0.0125 3.175 2.875 73.03
3 8 0.0125 3.175 3.5 88.9
3 1/2 8 0.0125 3.175 4 101.6
4 8 0.0125 3.175 4.5 114.3
5 8 0.0125 3.175 5.563 141.3
6 8 0.0125 3.175 6.625 168.28

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