What are the Main Olet Fittings?

Wednesday May 9th, 2018 | Francesco Grillo | Expertise

Olet Fittings (also called Branch Connection Fittings or Outlet Fittings) are fittings which provide an outlet from a larger pipe to a smaller one (or one of the same size).

The main pipe onto which the branch connection is welded is usually called the Run or Header size. The pipe to which the branch association or connection gives a pipe is conventionally called the Branch or Outlet estimate. Branch connections are in all sizes, sorts, bores, and classes, in various steel grades.


13 Types of Branch connections

There are 13 types of Branch Connections including:

  1. Weldolet (WEL)
  2. Threadolet (TOL)
  3. Sockolet (SOC)
  4. Elbolet (ELO)
  5. Insert Weldolet
  6. Brazolet
  7. Coupolet
  8. Nipolet
  9. Flexolet
  10. Latrolet (LOL)
  11. Sweepolet
  12. Weldoflange
  13. Nipoflange


Unless otherwise specified, the above trademarked names are registered by Bonney Forge. These fittings can be also found under different names. The user must verify that the fittings meet applicable standards, such as ANSI/ASME B16.9, ANSI/ASME B16.25 or MSS SP-97.

The mostly used olet fittings are sockolets and threadolets, weldolets and elbolets.

The weldoflange is a combination of a Welding Neck flange and a supposedly weldolet, while the nipoflange is a combination of  a Welding Neck flange and a nipolet.


A sockolet has the same basic design as a “weldolet” or “threadolet” where the major difference is that a sockolet has a socket for welding while the weldolet has got a buttweld connection. This makes a 90° branch and comes in full size or reducing for a straight piece of pipe. Sockolets are available in Class 3000, 6000 and 9000 for high pressures.



A threadolet has the same basic design as a weldolet. However the main difference is the fitting has a female threaded connection to link to the branch connection. This makes a 90° branch and comes in full size or reducing for a straight piece of pipe.

Typically, it is in the size range of 1/2″ to 2″ and is welded over a hole either drilled or burned in the pipe.



An elbolet is used on 90° long radius elbows (most common), short radius elbows (seldom used) and can be used on 180° returns. It is typically used for instrumentation connections and thermowells. Thermowells are tubular fittings used to protect temperature sensors installed in industrial processes. A thermowell consists of a tube closed at one end and mounted in the process stream.

Elbolets can be used as a drain connection when there is not enough room to use a Weldolet. The Elbolet is available with buttweld, socketweld or threaded connections.



Weldolets  are the most well-known among all the olets and are well-suited for high pressure weight applications. These are principally sorted as butt weld fittings, as these are welded into the branch pipe. .

A Weldolet® makes a 90° branch connection and – comes in full size or reducing for a straight piece of pipe. A weldolet is designated by the run length by the branch length. For example a 6-inch weldolet on a 10-inch pipe would be a 10×6 Weldolet. A weldolet is designed to minimize stress concentrations and provide integral reinforcement without the need for reinforcing the weld.


Weldolets Main Specifications

Type: Forge Pipe Olets / Forge Pipe Outlets

  1. Size: 1/8″NB TO 4″NB (DN6 x DN100)
  2. Class: 3000 LBS, 6000 LBS & 9000 LBS (Sch40, Sch80/Xs Sch160 Xxs)
  3. Standards: ASME/ANSI B16.11, MSS-SP-97, MSS-SP-79, JIS B2316, BS 3799, etc.
  4. Connect Type: Welded, threaded, BW, SW
  5. Materials: Stainless steel: ASTM A182 F304, F304L, F316, F316L, F317L, F321, F321H, F347, F347H, F310, F44F51, S31803, A182, F43, S32750
  6. Line Pipe: ASTM A694 F42, F46, F52, F56, F60, F65, F70Low


Optional Value Added Services: Hot Rolling, Cold Rolling, Galvanizing, Heat Treatment, Tempering, Electro Polishing, Threading, Sand Blasting, Soldering.

Steel Available can supply through its network of qualified manufacturers and stockists all types of branch connection fittings as per customer preferences.



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Please notice that you might be interested in the other product-related articles we’ve published:

  • What are the Main Types of Flanges?

  • Conferences, Trade Shows and Exhibitions 2018

  • Counterfeit Steel is a Big Worry in the Industry


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