NPT Hidrolik Bağlantı
NPT (National Standard Pipe Diameter), or National Pipe Tapered, is an American standard defined under AMSE B1.20.1. This NPT Bağlantı Parçaları standard specifies the dimensions and tolerances of tapered threads on pipes and fittings. Unlike straight threads, tapered threads provide a more reliable seal, especially when used with sealant materials such as Teflon tape. This standard is over a hundred years old and was originally developed for plumbing applications; however, it has also been effectively applied to hydraulic and gas conveyance applications.
NPT Threads Characteristics
NPT threads are defined by the following features:
- The taper angle is 1O 47’ (measured from the center axis of the NPT fitting)
- 60 ° angle between each crest and trough
- Flat crests and troughs
- Pitch (the distance between threads) is measured in threads per inch (TPI)
- The outer diameter of an NPT fitting is measured at the midpoint of the taper
Advantages of Using NPT Thread Fittings
NPT Thread Fittings can be assembled in a simple manner as the metal-to-metal contact offers an excellent seal.
NPT Thread Fittings has multiple sizes and materials to choose from. This allows you to use them for many applications at varying pressures.
Disadvantages of Using NPT Thread Fittings
The metal-to-metal contact in NPT fittings relies on the deformation of the threads to form a secure seal.
so it cannot use them in applications that require frequent disassembly.
If used improperly, that is, without correct alignment, overtightening, or wrong sizing, ports may expand, and cracks may form on the threads.
This, in turn, leads to the formation of leakage pathways from where the medium can leak out. It is for this reason that NPT fittings are not recommended for extremely high-pressure applications.
NPT Threads Sizing Chart
NPT defines both internal and external threads on fittings that conform to the standard; hence sizing charts give diameter measurements for both male and female parts. As a result, all male and female fitting types have consistency, adhering to the same taper rate – change in thread diameter per unit length. For the NPT standard, the taper rate is ¾ inch per foot or 1/16 inch per inch.
| NPT Size | O.D. of male threads (in.) | O.D. of female threads (in.) | Threads/in. |
| 1/8 | 0.405 | 0.36 | 27 |
| 1/4 | 0.54 | 0.47 | 18 |
| 3/8 | 0.675 | 0.59 | 18 |
| 1/2 | 0.84 | 0.75 | 14 |
| 3/4 | 1.05 | 0.95 | 14 |
| 1 | 1.315 | 1.2 | 11.5 |
| 1 1/4 | 1.66 | 1.56 | 11.5 |
| 1 1/2 | 1.9 | 1.8 | 11.5 |
| 2 | 2.375 | 2.27 | 11.5 |
