Are you doing a DIY plumbing project and wondering how to measure pipe nipples? Or maybe you’re a plumbing novice curious about how to measure pipe nipples?
Ordering the right size nipple is important in any successful plumbing installation. These small but essential fittings make all the difference in ensuring leak free low pressure piping systems.
So how do you measure pipe nipples? This is a common concern among plumbing novices who want to understand the dimensions of pipe fittings.
Determining your pipe nipple size is simple, as you will learn in this guide. Read on for details on pipe nipples and how to measure accurately when ordering these necessary fittings.
What is a pipe nipple?
A pipe nipple is a fitting made from a short piece of pipe and usually comes with male threads on both ends. A nipple acts as an adapter, connecting two pipes or female threaded fittings.
Manufacturers make nipples by cutting pipe to a specific length and creating the specific end connections that make the nipple unique. Like pipe, nipples can be welded or seamless.
Nipples usually come in different lengths, but most are around 12”. Before we discuss how pipe nipples are measured, let’s first look at the most common types of pipe nipples.
The most common types of pipe nipples
1. Close or leaking nipple
One of the most common pipe nipples is the close nipple, also known as the rolling nipple. With this type of nipple, the entire short pipe is threaded with male threads. So when you connect a pipe to each end of the nipple, you won’t see the nipple threads. The pipes or fittings on both sides come together, hiding the pipe nipple below.
A disadvantage of a close nipple is that it can be difficult to unscrew from a pipe or fitting. If you want to unscrew the connection, you must grip one of the threaded ends of the nipple with a pipe wrench, which could damage the threads, requiring replacement of the nipple. A nipple wrench to grip the inside of the pipe or fitting can minimize thread damage.
2. Hexagon nipple
A pipe nipple has a small unthreaded space between the two threaded ends. You can place a wrench on the unthreaded space to grip the nipple and avoid damaging the threads.
The unthreaded middle space in some nipples has a hexagonal pattern that resembles a nut. The hex pattern provides superior grip compared to a smooth pipe nipple.
On some nipples, the unthreaded hex space is slightly longer, making the threaded ends shorter. This type of nipple is known as a long hex.
3. Nipple reduction
Sometimes you may want to connect pipes or fittings of different sizes, meaning one fitting or pipe may be larger than the other. In this case, it is best to use a reducing nipple, also known as an uneven nipple.
A reduction nipple has the usual male threads on both ends, but with different diameters. One end takes a parent pipe with a larger connection, while the other end connects to a smaller pipe or fitting.
Be careful when connecting a large pipe to a small one. Increased flow and pressure in the smaller fitting or pipe can cause a sudden and potentially dangerous explosion.
4. Hose nipple
Another common type of nipple is the hose nipple. As the name suggests, these nipples connect the pipe to the tubing.
At one end of the nipple is a male threaded connection, while the other end of the nipple has a hose barb. The barb is usually more or less the same size as the threaded end of the nipple.
5. Welding nipple
Welding nipples have a threaded end and an unthreaded end that resembles a normal pipe. This nipple is handy when connecting a piping system to fittings or welded pipes.
The unthreaded end has a larger surface area to take the welded fittings, ensuring a strong connection. Connecting pipes/fittings to the threaded end is easier when the unthreaded end is firmly connected to the welded fitting.
When ordering pipe nipples, you need to know the type of nipple that best suits your plumbing installation. In addition to the length and type of pipe, you should also understand the end connections required for pipe installation.
These are the most common pipe nipple end connections:
- Both single ends (PBE): This nipple has wireless ends. Connect a socket welded to the pipes.
- Thread both ends (TBE): Many pipe nipples are threaded at both ends and help connect pipe or female threaded fittings.
- Both Beveled Ends (BBE): This pipe nipple connects welded pipes or fittings. It has chamfered ends on both sides of the nipple.
Other variations include a threaded end, a plain end, and a chamfered end. Your choice will depend on the design and operation of the piping system.
How to measure pipe nipple length?
When determining the right type of pipe nipple to buy, you should specify the following:
- Inner or outer diameter
- Pipe nipple length
- Preferred nipple material
- End connection type
How are pipe nipples measured in terms of length? The length of a pipe nipple is the total length of the pipe from one end of the nipple to the other. This formula applies if the pipe nipple is plain on both ends, threaded on both ends, plain on one end and threaded on the other. You can easily determine the length of the nipple using a caliper or a thread and a measuring tape.
When the pipe/fitting is installed on a pipe nipple, you can determine the length of the nipple by subtracting the thread engagement of both ends of the nipple. Engagement is the length of pipe inserted into the nipple to achieve a snug, hand-fitted seal.
In cases where female threaded fittings close together so that the nipple does not show, the close length is calculated as twice the thread engagement.
Use a nominal diameter conversion chart to determine the precise pipe nipple length in inches.
How do you determine pipe size?
In addition to learning how to measure pipe nipple size, you’ll also need to know how pipe size is measured. The advantage is that determining the pipe size is easy – all you need is the outside diameter for male threads and the inside diameter for female threads.
To measure pipe size for male pipe/fittings, follow these steps:
- Wrap a small string around the pipe
- Use a pen to indicate where the string touches
- Measure the string from the tip to the marked point using a tape measure or ruler. This is the circumference of the pipe.
- The diameter is obtained by dividing the circumference by 3.14
- Use the nominal diameter conversion chart to convert diameter readings to nominal diameter more accurately. The nominal diameter is the actual size of the pipe.
The steps for measuring the pipe size of a female threaded pipe are as follows:
- Place a tape measure or ruler over the opening of the pipe to measure the inside diameter.
- Use the nominal diameter chart for pipe sizes to convert the inside diameter to the nominal diameter, which is the actual pipe size.
Tips for measuring pipe fittings metric
Pipe fittings, including metric pipe nipples, are quite common. Metric threaded fittings are also classified as tapered because the threads taper the further you go in.
If your pipe/fitting has metric threads, you should have the correct thread dimensions before ordering a pipe nipple that can take metric threads.
So how do you measure metric pipe fittings? Here’s a step-by-step guide:
Measure the thread pitch using a pair of calipers or a thread gauge. The thread pitch is measured in mm and usually measures 1.0, 1.5. or 2.0, but you can find fittings with larger thread pitches.
Determine the inside diameter for female threaded fittings and the outside diameter for male threaded fittings. This is how the pipe thread is measured. (See guide above to determine pipe size).
Use a metric thread specification chart to identify a thread marking that will give you an approximate measurement of the metric pipe fitting. A thread marking combines the pitch measurement and the outside diameter of the fitting.
Summary: How are pipe nipples measured?
Pipe nipples are important to ensure safe and secure connections in pipe systems. The correct nipple type and size makes a world of difference to the integrity of any plumbing system.
Understanding how pipe nipples are measured will help you choose the right fittings. The numbers may seem confusing at first, especially since you should be converting internal and external diameters to nominal ones.
But with the right tools and a simple formula to follow, you should quickly learn how to measure pipe nipples and even determine pipe sizes. I hope this handy guide helps you understand how to measure pipe nipple length and size.
