Table of Contents

You’ve probably come across these terms if you’ve ever dabbled in plumbing or piping projects. NPT and MIP fittings. Sounds complicated, right? But what exactly are these? What sets them apart? Let’s dive in, shall we?

Introduction to Pipe Fittings

Imagine a puzzle; pipe fittings are the essential pieces that connect the puzzle pieces (pipes) together, enabling a seamless flow of fluids. They’re like the unsung heroes of any plumbing or piping system. Now, there are various types of tube fittings, but today we’ll focus on two: NPT and MIP fittings.

What is an NPT Fitting?

National Pipe Taper (NPT) NPT, or National Pipe Taper, is the U.S. standard for tapered threads used to connect pipes and fittings. It is the U.S. standard thread used for malleable iron pipe with a slight taper, the NPT standard includes a slight taper between male and female connections.

Fittings with male (external) threads are often referred to as MPT (Male Pipe Thread) or MNPT (National Male Pipe Thread), while fittings with female (internal) threads are referred to as FTP (Female Pipe Thread) or FNTP (National Female Pipe Thread). William Sellers, an American businessman and mechanical engineer, invented a uniform thread system that later became the NPT standard in 1864. The most common materials are iron and brass, usually used for low-pressure high-pressure applications, while stainless steel and carbon are mostly used for high pressure applications.

MIP fittings
MIP fittings

Key Features of NPT Fittings

NPT fittings are characterized by their tapered threads, which create a tight seal through the deformation of the threads when tightened. This unique feature makes them ideal for high pressure applications.

What is an MIP Fitting?

Male Iron Pipe (MIP) MIP, or male iron pipe, is one of two commonly used components in heavy-duty threaded pipe connections. A male iron pipe, as the name implies, is a pipe that has threads on the outside, such as a pipe fitting. However, FIP (internally threaded iron pipe) fittings are threaded on the inside. MIP is a pipe fitting with NPT threads, usually made of stainless steel and brass. Although the name says iron, MIP fittings are not always made of iron. If one side of the fitting is MIP and the other is FIP, it is often called mip by slip.

MIP fittings are used primarily with FIP fittings and are used in many different ways in commercial, residential, and industrial piping systems. They are used in heavy-duty applications such as high-pressure piping systems or natural gas transmission pipelines. Depending on the application, several different materials are used to make MIP fittings.

NTP fittings
MIP fittings

Key Features of MIP Fittings

Unlike NPT fittings, MIP fittings have straight, parallel threads. They require a washer or sealant to ensure a water-tight connection, making them ideal for less pressurized applications.

Comparing NPT and MIP Fittings

Now that we’ve got the basics down, let’s get into the real deal: the differences.

Differences in Design

As mentioned, NPT fittings have tapered threads, while MIP fittings have straight threads. This difference in design directly influences how they function and where they’re applied.

Differences in Functionality

NPT fittings create a more robust seal due to their tapered design, suitable for high-pressure applications. Conversely, MIP fittings, with their straight threads, require additional sealants, making them less ideal for high-pressure scenarios.

Differences in Applications

NPT fittings are common in various industrial applications due to their robustness, while MIP fittings are often found in residential and light commercial settings, where high pressure isn’t a common concern.

Summary of NPT and MIP In short, NPT is a standard for the definition of fittings regulated by the American National Standards Institute (ANSI) and approved for use in residential and commercial piping systems. However, many people interchange NPT with MIP, fitting with NPT threads. Fittings with male threads are called MIP, while fittings with female threads are called FIP. NPT and MIP work together but do not mate with any other type of fitting. NPT fittings are usually used in residential and hydraulic systems, while male iron pipe has a wide range of applications, including commercial and residential plumbing systems.

Choosing Between NPT and MIP Fittings

With the differences laid out, how do you choose?

Factors to Consider

Here are some things to ponder upon:

Your Specific Needs

If you’re dealing with high-pressure systems, NPT fittings might be your best bet. But if you’re looking at a home plumbing project, MIP fittings could be just the thing.

Installation Process

NPT fittings can be more challenging to install due to their tapered design, while MIP fittings can be simpler, needing just a washer or sealant.

Cost Considerations

While the price can vary, it’s essential to consider the longevity and durability of the fitting type you choose. It’s not always about the initial cost, but the long-term value it provides.


So, there you have it, a clear-cut comparison between NPT and MIP fittings. Both types serve different purposes and come with their unique set of advantages. The key lies in understanding your specific needs and choosing the right fitting accordingly. Remember, the right fit can make a world of difference!


  1. Are NPT and MIP fittings interchangeable? Not usually. Because of the differences in thread design, they usually cannot be used interchangeably without risk of leaks or damage.
  2. Can I use an NPT fitting for low-pressure applications? Yes, but it might be overkill. MIP fittings could provide a more cost-effective solution for such scenarios.
  3. What kind of sealant should I use with MIP fittings? Teflon tape or pipe dope is typically used to ensure a secure seal with MIP fittings.
  4. Are there other types of pipe fittings besides NPT and MIP? Absolutely! There are many types, such as compression fittings, flare fittings, and more. The choice depends on your specific application.
  5. Which fitting type lasts longer, NPT or MIP? Both can have long lifespans when used in their appropriate settings and properly maintained.

If you have tube fitting needs, please contact Huiqi.

Contact Us
Please enable JavaScript in your browser to complete this form.
Related Products
No data was found
error: Content is protected !!