Do you know what exactly the difference between NPT and NPTF ? Get here with it application

The application of npt and nptf pipe thread ranges from electrical conduits to high-pressure piping solutions that carry materials like natural gases and chemically aggressive liquids. Both the npt and nptf connector uses a thread taper for providing a solid, and vibration-free connection. The npt compression fitting is standard and readily available, but there are specification recommendations for installations and sealing for specific material of the fitting, like plastic or metal. Both the threads have different installation styles and the differences are primarily based on gauging the threads for conformation before the installation process begins.

NPT or National Pipe Taper can be defined as a tapered pipe thread used for general purposes. On the other hand, NPTF or National Pipe Taper Fuel is a dryseal pipe taper thread. Both the pipe threads look identical, and they also depend on their thread interference for a robust and tight connection. The tapered design is primarily responsible behind making this thread interference.

Difference Between NPT and NPTF Threads


What is the difference between npt and nptf?

The difference between npt and nptf threads lie in the way they create a leak-proof seal. Both the threads would require proper installation but to get a proper npt connection with reduced risk of leakage, using an appropriate thread sealant is very crucial. However, for nptf fitting, assembling them correctly would create leakage free connection and there is no need for a sealant.

Some other difference between npt and nptf would include:

  • Even though the shape of both the threads are the same, the root and crest height of the nptf are adjusted so as to create an interference fit. This help to create a mechanical seal through the thread form deformation at the time of assembling.
  • The compression to npt adapter is primarily used in mechanical applications or services that involve low-pressure air or fluid. On the other hand, the nptf is suitable for high-pressure applications like the hydraulic systems.


Must Know When Should NPTF thread use and Some facts that you should consider before buy material

When to use nptf threads?
The female nptf threads are preferred over the npt connections when:

  • Using the sealant can increase the risk of fluid or gas contamination that flows through the system.
  • In case of critical applications, where the npt threads might fail due to high temperature or high pressure environments.


Some important points to remember
  • The nptf to npt adapter can be connected with the help of thread sealants.
  • They can be reused under some particular conditions and with caution.
  • The special requirements for installation and assembly of both the threads should be followed to get a leakproof connection.


The nptf hydraulic fittings have conical threads and they use adjustable screw connections in the T-adpater and angle versions. These threads ensure leak-proof connection between the metal and metal. Herein, the nptf male and female threads are connected in the thread base.

The compression fitting to npt can be described as a push-to-connect fitting that helps to join pipes and tubes with the npt to compression male or female thread. The fittings are generally made of stainless steel and they effectively resist the process of scaling, rusting, and corrosion.

Know more About NPT and NPTF pipe threads tapered and how it will be done

Why are the npt and nptf pipe threads tapered?

The npt and nptf coupling threads are tapered so that the connections cause the threads to wedge during the installation process. The wedging helps to create a strong connection which will not get loose due to vibration. Slight difference between the threads of the npt and nptf adapter determines when they would need sealants to get a leak-proof connection.

Get full Installation And Assembling Process of NPT To NPTF Adapter online here
Importance of proper installation and assembling

Proper installation of the npt and the male nptf with the nptf female is very important so as to ensure leakage free connection and proper functioning. The tapered threads help to create an elastic stress which creates a friction between the mating surface. That makes both the npt and nptf connections tight and robust.

In order to connect npt to nptf adapter, a thread sealant is needed to create a leakproof connection. The connection between nptf male to npt female can be done. But it is important to note that while npt threads can be reused with careful inspection and caution (as the thread can potentially get damaged due to overtightening). It is not advisable to reuse the nptf thread.

Lets check NPT And NPTF Threads Interchangeable? and its full form
Are Npt And Nptf Threads Interchangeable?

They are not interchangeable, Both NPT and NPTF seem to be the same. Both have the same thread lengths or depths as well as the same pitch diameter at the top of the hole for the internal thread or the pipe end on external threads. The sizes of the threads at their root and crest, however, differ slightly.

  • NPT = National Pipe Thread
  • NPS = National Pipe Straight
  • NPTF = National Pipe Thread Fuel


Thread size Major Diameter (mm) TPI
1/8” – 27 NPT 10,287 27
1/16” – 27 NPT 7,938 27
2” – 11 ½ NPT 60,325 11,5
3/8” – 18 NPT 17,145 18
1/4” – 18 NPT 13,716 18
3/4” – 14 NPT 26,670 14
1/2” – 14 NPT 21,336 14
1” – 11 ½ NPT 33,401 11,5