Article
When a small branch is needed on a large header, a full reducing tee is often oversized and expensive. Branch outlet fittings, known as olets, solve this. An olet is welded on top of the run pipe over a hole and gives an integrally reinforced branch connection.
The main olet types
| Olet | Branch end | Typical use |
|---|---|---|
| Weldolet | Buttweld (bevelled) | Branches that continue as buttweld pipe; larger branch sizes |
| Sockolet | Socket weld | Small-bore branches, usually 2" and below |
| Threadolet | Female threaded (NPT) | Instrument, vent and drain connections |
| Elbolet | Buttweld, SW or threaded | Branch on the outside of a long radius elbow, often for thermowells |
| Latrolet | Buttweld, SW or threaded | 45° lateral branch |
| Nipolet | Plain or threaded nipple | Short valve or drain connections |
Why use an olet instead of a tee?
- Cost and weight – far less material than a reducing tee on a big header.
- Flexibility – can be placed anywhere along the pipe, even added later.
- Reinforcement – the olet body provides the reinforcement the opening needs, so no separate reinforcing pad is required when correctly selected.
Standard and ratings
Olets are covered by MSS SP-97. Weldolets are matched to the branch pipe schedule (standard, XS, SCH 160 and so on). Sockolets and threadolets are rated by class: 3000 and 6000 for the most common sizes, with 9000 for heavy service. Materials follow the forging standards: ASTM A105 for carbon steel and ASTM A182 F304/F304L, F316/F316L and other grades for stainless steel.
Ordering tip: give both sizes
An olet is shaped to sit on a particular run size. Always state the run size and the branch size, for example Weldolet 10" × 2", STD. Some olets cover a range of run sizes, but the supplier needs the run size to confirm the right contour.
A complete description
Weldolet, Run 12" × Branch 3", SCH 40S, ASTM A182 F316L, MSS SP-97 – 10 nos
Frequently asked questions
What is the difference between a weldolet and a sockolet?
A weldolet has a bevelled buttweld branch end, while a sockolet has a socket weld end for small-bore pipe.
Which standard covers olets?
MSS SP-97 covers integrally reinforced forged branch outlet fittings.
Why must the run size be given for an olet?
The base of the olet is contoured to fit the curvature of the run pipe, so the run size decides the correct fitting.
Key takeaways
- Olets give a reinforced branch from a larger pipe at low cost.
- Weldolet = buttweld, sockolet = socket weld, threadolet = threaded.
- Always state run size × branch size and the schedule or class.
Need these products?
Sawariya Metal Industries supplies stainless steel pipes, flanges and buttweld pipe fittings from Mumbai to buyers in India and overseas. Send your size, grade, standard and quantity through our enquiry form and we will reply with a clear quotation and the test documents you need. You can also browse our stainless steel pipes, flanges and buttweld fittings.