In this lecture, you will learn about olets, which is a self-reinforced branch connection.

There are two ways for branching from the run pipe.

  • 1st is a pipe-to-pipe branching. Either with a reinforcement pad or with the help of a standard tee. When we make an opening in the pipe for the pipe to pipe branching without using TEE, it will weaken the pipe. To avoid this, an additional reinforcement pad is welded to the pipe, and this type of branch connection is fabricated at the site.
  • In the second method, instead of an additional reinforcement pad, you used a heavier, specially designed branch that works as a Self-reinforced branch.
  • This Specially designed branch connection is known as “Olets.” A Company called Bonney Forge has pioneered this concept, and olet is their registered trademark.
  • Whenever branch connections are required in size where reducing tees are not available and/or when the branch connections are smaller than header size, Olets are generally used.
Olets self reinforced branch connection
  • Self-reinforced branches (Olets) are designed as per Process Piping Code ASME B31.3.
  • Another standard available is MSS SP-97 which is the Manufacturers Standardization Society.
  • The most commonly used olets are;
    • Weldolet, Sockolet, Thredolet, Elbolet and Nipolet,
    • Special Olets such as Latrolet, Flexolet, and Coupolet are also used sometimes.


  • Weldolet is 90° branch connection
  • It comes in full size or reducing the size (Full size is when you take a branch of the same size as run pipe size for example, 3 inch to 3 inch. And reducing size is when branch size is less than run pipe size 3 inch to 1 inch)
  • Weldolet’s end is suited for the butt welding connection.


  • Sockolet is the same as weldolet but with socket end.
  • It is 90° branch connection
  • Comes in full size or reducing the size
  • The end connection is suited for socket welding

Flange and Olet Quiz – Test yourself, Take This Quiz


  • Thredolet is 90° branch connection that comes with a threaded end connection
  • It also Comes in full size or reducing the size
  • The end connection is suited for threaded joint


  • Elbolet is a special type of olets that fits on the elbow surface. It is 90° branch connection and comes in different types of ends that suit for butt welding, socket welding and threaded joint


  • Nipolet is a weldolet with an extended pipe body. As you can see in the image
  • It is 90° branch connection and comes in different types of ends that suit for butt welding, socket welding, or threaded joint.


  • There are some special olets also used in piping, such as
  • Latrolet that is used for taking branch which is not at 90 degrees to run pipe.
    • Latrolet comes in a 45°or any other special degree as required by the purchaser.
    • End connections of a Latrolet can be butt welded, socket welded, or threaded.


  • Coupolet is Olets with female NPT thread that uses for low-pressure This will reduce the use of one sockolet and one coupling.


  • Sweepolet is used for large-size branch connections.
  • It provides a smooth flow transition from a run pipe to a branch pipe.
  • Sweepolet is used in piping header and pressure vessel when smooth flow transition is necessary, and a standard tee cannot be used.

Weldolet, Sockolet, Thredolet, Elbolet, Nipolet, Latrolet, Sweepolet and Coupolet are Registered Trademark of Bonney Forge. Images – Bonney Forge

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Varun Patel - HardHat Engineer

About Author: Varun Patel is a Mechanical Engineer and an Oil & Gas Professional. He is a Certified Project Management Professional – PMP® from PMI® USA. With over nineteen years of experience, he has worked with Fortune 500 Oil & Gas Companies. Know more.