Branch Connections: A Guide to Choosing and Using Olet Style Connections

From the various styles of olet branch connections to the different uses and picking the perfect options for your project, we’re covering everything you need to know

Combining a self-reinforcing design with a range of different formats and sizes, olet style branch connections are an ideal alternative to reinforcement pads and standard pipe tees.

Different designs offer solutions for virtually any pipe size or shape while also providing numerous connection options and solid, long-lasting connections.

What is an Olet?

Before we dive into the common olet types and how they differ, it’s important to look at some common characteristics and get an idea of how they work.

Typically, when branching a pipe, you can use one of a few options:

  • A standard piping tee

  • A saddle type pipe connection with or without a reinforcement pad

  • An olet

Pioneered and trademarked by Bonney Forge, olets provide the same branching functionality of a standard tee but with a self-reinforcing design that requires less on-site fabrication.

Most common olet designs are built for use as a 90-degree branch connection. However, specialty designs are also available for use on elbow bends or to make 45-degree connections.

Olets require welding for proper installation to a pipe, pressure tank, or other piping system components.

However, they are available with a variety of end connections to suit different uses and connection methods.

This is the most common way of separating various olet types.

Because of how olets are designed, they will only work when branching between equal or smaller size pipes.

Types of Olets Explored

Most olet types will describe their properties right in the name. That can take the confusion out of limiting your initial options.

Let’s look at common types of olets and their characteristics.


Welded onto the outlet pipe, Weldolets® feature a 37-degree bevelled end.

It is one of the most common branch connections available and considered a butt-weld fitting due to its design. This style of olet is used in high temperature and high pressure conditions.


Instead of using a bevelled end, Sockolets® utilize a socket consisting of a bore matching the outlet bore and a counter bore roughly the size of the outer diameter of the outlet.

This creates a socket in which the pipe can sit to make welding and installation easier. Available in 3000#, 6000#, and 9000# classes, Sockolets® are considered socket fittings.


Using a threaded end, Thredolets® feature a bore matched to the outlet bore to allow connection with no welding.

Considered a threaded fitting, Thredolets® are most commonly available in 3000# and 6000# classifications.


Allowing for 45-degree lateral connections -- as opposed to the typical 90-degree connection of other olet types -- Latrolets® can feature butt-weld, socket weld, or threaded connections to suit various applications.

They are most commonly available in 3000# or 6000# classifications.


While most olets require a straight run of pipe for installation, Elbolets® offer a 90-degree branch connection option for elbows and bent pipes.

Typically used for Thermowell and instrumentation installations, they are available in butt-weld, socket weld, and threaded applications to suit a range of uses.

While most commonly used with 90-degree long radius elbows, options are available for short radius elbows.


Available in a variety of end types -- including male-socket (PE), butt-weld, and male threaded -- Nipolets® feature an extended pipe body and are available in 90-degree branch connection configurations.

Often used in valve take-offs, drains, and vents, Nipolets® are available in varying lengths ranging from 3.5- to 6.5-inches.


Designed to provide smooth flow transition from the run pipe to the branch pipe, Sweepolets® are typically used in large size branch connections.

This butt-weld branch connection is also contoured and integrally reinforced to lower stress intensification factors. This provides a low stress solution with a long fatigue life.

The design also allows for easy radiography, ultrasound, or other non-destructive inspection means for applications with such requirements.

Insert Weldolets®

Contoured like a Sweepolet®, Insert Weldolets® provide easy-to-examine attachment welds in a design similar to Weldolets® with the addition of a raised section on the connecting end to assist with connection.

Branch Connections and Run Sizes

When choosing a branch connection fitting, it is important to consider run sizes and how the fitting will integrate into your intended piping system.

Branching connection fitting outlet sizes are designed to fit several run pipe sizes.

For example, a 1/2-inch olet fitting marked 2-inch by 36-inch (run) by 1/2-inch will fit all run pipe sizes from 2-inches to 36-inches.

When placed on a 36" Run Pipe, there will be a maximum radial gap of 1/16" between the top of the Run Pipe and the base of the fitting at the crotch.

This gap is negligible when welding.

However, it’s critical to ensure that modifications to accommodate installation of the olet do not stray from the critical engineering design.

For example, the crotch or heel of an olet cannot be manipulated or shortened.

Instead, the skirt or toes should be manipulated or shortened where required. This dynamic is a major part of why size ranges exist.

You’ll find an example of this is the diagram below.

The “A” and “E” dimensions cannot be altered because it will change the center of run pipe to end (or insert ledge on socket weld olets) depending on the engineering practice.

Unsure of the proper branch connections for your system? Have questions about sizes, materials, and types? As a leading provider of industries across North America for more than 40 years, the expert analysts at Unified Alloys can help you find the perfect components for your needs. Contact us today or consult our pipe fittings catalog for our full range of branch connections and other fitting types.

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