Branch Connections: PypeServer’s Guide to Selecting and Using O-lets

We’re covering everything you need to know about O-let branch connections and selecting the right options for your next project.  O-let-style branch connections are perfect alternatives to standard pipe tees and reinforcement pads. Different O-let designs offer solutions for virtually any pipe size or shape while providing numerous connection options and solid, long-lasting connections.

An O-let – What is it?

You typically have several options when branching a pipe:

• The standard piping tee
• The saddle-type pipe connection with/without a pad reinforcement
• An O-let

O-lets were developed and originally trademarked in 1931 by Bonney Forge. They provided the same branching functionality as a standard tee but required less on-site fabrication with a self-reinforcing design. Today, there are several large O-let suppliers, including ASC (Anvil).

O-lets are typically used for 90-degree branch connections. However, specialty designs are available for use on elbow bends or to make 45-degree connections.

O-lets require welding to properly install on a pipe, pressure tank, or other piping system components. However, they are available with various end connections to suit different uses and connection methods. O-lets are specifically designed to only work when branching between equal or smaller pipes.

Exploring Types of O-lets

O-let names tend to be somewhat self-descriptive. Below are a few popular types of O-lets and their characteristics. All trademarked names listed below are property of Bonney Forge but other manufacturers have similar designs under different names.

Weldolets® – Welded onto the outlet pipe, Weldolets features a 37-degree beveled end.

This is one of the most common branch connections available and is considered a butt-weld fitting to be used in high-temperature and high-pressure conditions.

Sockolets® – Instead of using a beveled end, Sockolets utilizes a socket consisting of a bore fitting the outlet bore and counter bore approximately the size of the outlet’s outer diameter.

The outlet bore creates a socket where the pipe can sit to make welding and installation easier. Available in classes 9000#, 6000#, and 3000#, Sockolets are considered socket fittings.

Thredolets® – Thredolets features a bore matched to the outlet bore to allow connection without welding using a threaded end. Considered a threaded fitting, Thredolets are usually available in 6000# and 3000# classifications.

Latrolets® – Latrolets allow for 45-degree lateral connections and can feature butt-weld, socket weld, or threaded connections to suit various applications. Latrolets are usually available in 6000# or 3000# classifications.

Elbolets® – Elbolets offers a 90-degree branch connection option for elbows and bent pipes. They are available in socket weld, butt-weld, and threaded to leverage a range of use cases. While typically used with 90-degree long radius elbows, some are available for short radius elbows.

Nipolets® – Nipolets are available in 90-degree branch connection configurations and various end types, including male-socket (PE), butt-weld, and male threaded. Often used in valve take-offs, vents, and drains, Nipolets are offered in various lengths ranging from 6.5 to 3.5 inches.

Sweepolets® – Created to provide a 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 reinforced to lower stress and extend fatigue life. The design of Sweepolets also allows easy ultrasound, radiography, and non-destructive inspection.

Insert Weldolets® – Insert Weldolets offer easy-to-examine attachment welds similar to Weldolets® bit with the addition of a raised section on the connecting end to assist with the connection. Insert Weldolets are contoured like a Sweepolet. 

Run Sizes and Branch Connections

O-lets are typically suited to a range of run pipe sizes. For example, an O-let fitting marked 2-inch by 36-inch (run) by 1/2 inch will fit all run pipe sizes from 2 inches to 36 inches in diameter. The geometry of the O-let is designed to accommodate the range of run sizes and relies on the weld attachment to compensate for any mis-match. It’s important not to modify the heel or crotch of the O-let for better fit-up.

Are you interested in learning more about proper branch connections for your system? Have questions about sizes, materials, and types? As a leading provider of fabrication workflow software, please get in touch with PypeServer.