Introduction

Maybe you always feel confused when you talk about the different standards of pipeline, pipe fittings or threaded connections. The most common types of pipe thread are PT(Taper Pipe Threads) and NPT (National Pipe Taper). Both of the two types are widely used in many industries. It’s important to know their differences to ensure the proper installation and leak-free. In this article, we will analyze the differences between them, to help you know their applications and compatibility.

The main difference between PT and NPT thread is the thread angle and the contour design.

The angle of screw threadsfor PT is 55 degree, always used in the countries of Europe and Asia.

The angle of NPTthread (National Pipe Taper threads) is 60 degree, which is always used in America and most areas of Canada.

Because the different angle of thread and design, PT and NPT threads are not interchangeable.

Now we have learned overview of their difference. Let’s learn more details, including thread outline, application and whether PT and NPT threads can be coordinated used in some conditions.

Thread Profile and Angle Differences

The main difference between PT and NPT threads is the thread angle. That’s the key reason that the two type can’t be compatible.

• PT threadsare mostly used in the standards of Europe and Asia. It has 55-degree angle, which is flatter than the angel of NPT thread.
• NPT threadhas 60-degree angel, which is a part of American pipeline standard. The steeper angel can create the tighter seal.

The difference of angle leads to the difference of thread outline. The conical degree of PT thread id less than NPT thread. This different design create different engagement system. So they can’t be compatible in most conditions.

Why Does Thread Angle Matter?

The thread angle is important for the fit between threads. The steeper angle, such as 60 degree of NPT, can provide the tighter connection, which is helps to form a more reliable seal under pressure. By comparison, 55-degreed PT threads can’t form the tight seal as NPT, so can’t be used in high pressure conditions.

The Role of the Thread Pitch

The thread pitch (the distance between the threads) is the other difference between PT and NPT threads . this difference leads to different locking methods. NPT threads have thicker pitch, that means NPT is more suitable for high pressure applications.

Compatibility Between PT and NPT

PT and NPT threads are not compatible, because of their different thread angel and pitch. However, in some instances, you can choose PT fittings with NPT threads which use adapter and sealer together.This compatibility issue often occurs in the pneumatic or hydraulic industry. At this point, a specialized adapter is needed to fit the P and NPT threads together.

Common Applications of PT and NPT Threads

PT and NPT threads are usually used in different industries. So, it’s important to choose the proper thread type.

• PT threadsare mostly used in water, gas, and oil systems in Europe and Asia.
• NPT threadsare often used in plumbing, gas fittings, and hydraulic systems in American and Canada.

Applications of PT Threads

• PT threads are often used in Europeanand Asian pipeline industries.
• PT and NPT threadsare both used a lot in hydraulic and pneumatic of thread pipe fittings.
• BSPT (British Standard Pipe Thread)can interchange with PT thread, but they aren’t quite the same.

Applications of NPT Threads

• NPT threadsare used a lot in North America, especially in water pipes, gas line and oil line.
• Both of them are widely used in hydraulicand pneumatic
• NPTF(National Pipe Taper Fuel)thread is the upgrade version,Used for applications that require leak free sealing.

Identifying PT and NPT Threads

When you are unsure about the type of thread, the following methods can identify them:

• Angle of the Thread:Distinguish by measuring the thread angle. If it is 60 degrees, it’s NPT; if it’s 55 degrees, it’s PT.
• Thread Pitch: Distinguish by measuring the thread pitch.Compared with PT threads, NPT threads pitches are relatively wide.
• Labeling: Some threaded products will be labeled with different types.If you see NPT, that means its American thread; if you see PT, that means it’s from Europe or Asia.

PT vs NPT: A Quick Comparison

 Conclusion

In summary, PT and NPT threads are both widely used in many industries. It’s important to know their differences, to make sure compatibility and free-leak. The main differences between them are thread angle, thread pitch and thread outline.In most cases, they cannot be directly exchanged. But in some special conditions, they can be exchanged with the cooperation of adapter and sealant. Before use PT and NPT threads together, you must check the thread specifications.