Elbows and tees terminology

On 2022-01-13

By Susan Brown

Elbows and Tees are often required in hydraulic applications as well as many piping and tubing applications. There are some words that are used to describe elbows and tees that may be a bit confusing. So just as described in our previous post about adapter terminology, it is critical to provide some key information about the parts that you are ordering…. And the same goes for tees and elbows.

For each Tee and Elbow that you require, suppliers need to know some…

Basic information

Geometry / Configuration Size for each end (inside diameter, generally) Orientation for each end (male or female) Threads for each end (NPT, JIC, BSPP, SAE/ORB, etc) Material (Stainless steel, Carbon steel, Brass and many more) And the supplier’s part number (if you have it)!


For elbows they need to know the degree of bend. Generally, this is 90 degrees or 45 degrees, but in some applications a very specialized elbow with other degrees of bend may be required.

In addition to all of the terminology described above, an elbow can also be described as a Street elbow (which means one end is a male NPT and the other is a female NPT thread).


How do you describe each part of a Tee, if one is different from the others?

Some people will talk about them like a T-shirt, so the arms of the tee and the body. Some will use the terms run and bull. Others will make an attempt to describe them but it ends up being very confusing and hard to be absolutely sure of what is needed. Still others will describe them as the run and the branch. This last one is generally the most common way to describe a tee.

One theory on where the run/branch terminology came from is based on the original piping being installed under the roads or along the streets. The water would ‘run’ down the pipes from one end of the street to the other, and would ‘branch’ off towards each house. So the ‘run’ of a Tee is considered the two ends that the liquid can flow through without having to change directions, and the ‘branch’ of a Tee is the end where the liquid would have to change directions.

There are also all sorts of other terms for tees used in different applications, such as split tee (where the branch end is half the size of the run ends), reducing tee (where the branch size is smaller than the run sizes), bar tee (where there is a bar across the female opening of the branch end). Each application creates their own terminology to fulfill their needs to describe a certain kind of Tee.

When talking about the sizes of each end, the run ends come first and the branch is last. So a part that has run ends in 3/4″ with the branch end of 1/2″, the part would be considered 3/4 x 3/4 x 1/2”.

If you are looking for tees and elbows, hopefully this has provided you with some guidance and reference to describe them in such a way that you can convey exactly what you need. If you have any questions, please do not hesitate to reach out to Aerocom Specialty Fittings Inc and we will be happy to help you out.

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