Field Weld Symbol
The field weld symbol is a small flag on a staff drawn where the arrow meets the reference line. It means the weld is made in the field, at the installation site, rather than in the fabrication shop. Like weld-all-around it is supplementary: the main symbol on the reference line still gives the weld type, size and side.
How to read the field weld symbol
Large structures are shipped in pieces and joined on site. The flag tells the shop to leave that joint unwelded (often with the edge preparation done) and tells the erector to weld it during installation.
The flag sits at the junction of the arrow and reference line, at right angles to the line. It does not change how arrow side and other side are read from the main symbol.
What each dimension position means
| Position | Meaning |
|---|---|
| Flag at the junction | Make the weld on site, not in the shop. |
| Weld symbol on the line | Weld type, size, length and side as usual. |
| Tail | Often holds the field procedure or WPS reference. |
Example callout, read aloud
“On site, weld a 5/16-inch fillet, 12 inches long, on the arrow side, using flux-cored arc welding.”
Example: reading the callout piece by piece
- Flag at the junction: field weld, so the shop ships this joint unwelded.
- Fillet below the line: arrow side, 5/16-inch leg.
- 12 right: 12 inches long.
- FCAW in the tail: flux-cored arc welding. The self-shielded version is common on site because it needs no shielding gas that wind could blow away.
Result: On site, weld a 5/16-inch fillet, 12 inches long, on the arrow side, using flux-cored arc welding.
When it is used
- Structural steel connections made during erection.
- Pipe tie-ins and closure welds at the installation site.
- Parts too large to ship welded, joined after delivery.
Common mistakes
- Welding a field joint in the shop. The flag means leave it for site, often because fit-up needs the final position.
- Leaving off the flag on site welds. Without it the shop assumes it should make the weld.
- Reading the flag direction as the weld side. Side still comes from the main symbol.
- Not giving a field procedure. Site conditions differ from the shop; reference the field WPS in the tail.
Related weld symbols
- Weld-all-around: The all-around circle also sits at the junction and is often combined with the flag.
- Fillet weld: Fillets are the most common field welds.
- Bevel groove weld: Field groove welds in steel connections are often bevels.
- V-groove weld: Pipe closure welds in the field are usually V-grooves.
- Back and backing weld: Field joints may need a backing weld or backing bar.
Every weld symbol page: welding symbols chart
Calculators and further reading
Frequently asked questions
What does the flag on a weld symbol mean?
Field weld: make the weld at the installation site rather than in the shop.
Does the direction of the flag matter?
The flag shows a field weld; it does not change which side of the joint is welded. Side comes from the main symbol.
Can a field weld also be all around?
Yes. Draw both the flag and the all-around circle at the junction.
Is a field weld held to a different standard?
It follows the same weld requirements, but the procedure may differ for site conditions. Check the WPS and code referenced on the drawing.
Sources
- AWS A2.4 Standard Symbols for Welding, Brazing, and Nondestructive Examination, American Welding Society
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