What Is a Weldolet and How to Take One Off?
A weldolet is a branch fitting welded onto a larger run pipe so a smaller pipe can branch off it. Each one means a fitting, a hole cut and two welds to price.
Common on process piping in refineries, chemical plants and power plants, wherever a smaller branch leaves a larger header.
How a Weldolet Is Installed
A weldolet sits on top of the run pipe, while a tee is cut into the line. A weldolet goes on in three steps.
Cut the Hole in the Run
The fitter marks the branch location on the run pipe and cuts a hole sized to the bore of the weldolet, then cleans the edge so the fitting sits flush on the pipe.
Weld It to the Run Pipe
The weldolet's base is shaped to the curve of the run pipe. It is welded all the way around where it meets the pipe, and the fitting's shape carries the reinforcement the branch opening needs.
Weld the Branch Pipe On
The branch pipe is beveled and butt welded to the weldolet's outlet, the same way two pipes are joined end to end. Where the layout allows, this is done in the shop as part of a spool.
Weldolet, Sockolet, Threadolet and Tee
All olets branch off a run pipe, and the difference is how the branch connects. A tee does the same job by being cut into the line, which adds a weld but suits branches close in size to the run.
- Weldolets take a butt welded branch.
- Sockolets and threadolets are used on small bore branches.
- Elbolets, latrolets and nipolets cover elbows, angled branches and vents.
| Fitting | Branch Connection | Typical Use |
|---|---|---|
| Weldolet | Butt weld | Branches on straight run pipe, including higher pressure lines |
| Sockolet | Socket weld | Small branches, usually 2 inches and under |
| Threadolet | Threaded | Small branches for instruments, vents and drains |
| Elbolet | Butt weld, socket weld or threaded | Branches off an elbow, often for thermowells |
| Latrolet | Butt weld, socket weld or threaded | Branches at a 45 degree angle |
| Nipolet | Male threaded or plain end | Vents, drains and valve connections |
| Reducing Tee | Butt welds, cut into the run | Branches close in size to the run pipe |
Olets Are Small, Easy to Miss and Heavy on Labor
A weldolet is one line on the bill of materials, but it carries a hole cut and two welds. For each one the estimator lists the fitting by run size, branch size, schedule and material, the weld to the run, the butt weld to the branch in diameter inches, and whether the work is done in the shop or the field.
| Weldolet 6 x 2 | 4 |
| Welds for weldolets | 8 |
| Sockolet 4 x 1 | 6 |
| Welds for sockolets | 12 |
| Threadolet 3/4" | 3 |
| Weld diameter inches | 34 |
Olets are spread across hundreds of isometrics, so they are easy to miss in a manual count. The Takeoff AI reads the isometrics, counts every olet by type and size, counts the welds that go with each one and returns a priced bill of materials, with each item highlighted to accept or reject.
- Every olet counted by type, run size and branch size
- The welds for each olet counted and converted to diameter inches
Small Fittings Still Need a Full Weld Count
Instrument connections, vents, drains and sample points all branch off with olets, and a process plant isometric can carry dozens of them. Each one adds welds that are easy to skip when the weld count is rushed before bid day. With fewer estimators and tighter bid windows, these small items are the ones most often left out of the labor number.
“One line on the bill of materials, two welds on the labor sheet.”
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What Is a Weldolet and How to Take One Off?
What is a weldolet?
A weldolet is a branch fitting welded onto a larger run pipe, with a butt weld outlet for a smaller branch pipe. It is one of the olet family of branch fittings.
What is the difference between a weldolet and a tee?
A tee is cut into the run pipe and needs three welds. A weldolet sits on top of the run pipe, needs two welds and is used when the branch is smaller than the run.
What is the difference between a weldolet and a sockolet?
A weldolet takes a butt welded branch. A sockolet takes a socket welded branch, where the pipe slides into the fitting, and is common on small bore pipe.
How many welds does a weldolet have?
Two. One joins the weldolet to the run pipe, and one butt welds the branch pipe to the weldolet's outlet. Both get counted in the weld takeoff.
Can software count weldolets on isometrics?
Yes. The Takeoff AI counts every olet by type and size on the isometrics, counts the welds that go with each one and returns a priced bill of materials traced to the drawing.