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Field weld symbol: what it means on a drawing

Fillet Gauge editorial teamSources checked 3 min read

The field weld symbol is a small flag drawn where the arrow meets the reference line. It means the weld is made at the job site, during erection or installation, instead of in the fabrication shop. Everything else on the symbol, the weld type, size, length and side, reads exactly the same as it would without the flag.

Two identical T-joints with a 1/4 fillet on the arrow side. The first symbol has no flag, a shop weld. The second has a filled flag at the arrow bend, a field weld
The weld is identical. The flag changes where it gets made.
Use this diagram

How to read it

  1. Look at the bend. The flag rises from the junction of the arrow and the reference line. If it's there, the weld is a field weld.
  2. Read the rest of the symbol normally. A flag on a 1/4 fillet below the line is a 1/4 fillet on the arrow side, made on site.
  3. Check for a circle at the same spot. Flag plus circle means field weld all around: made on site and carried around the full joint. See the weld all around symbol for the circle on its own.
  4. Check the tail. A process or WPS reference in the tail applies to the field weld just as it would in the shop. Field work often uses a different process from the shop, so read it.

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Symbols - Welding and NDE

On a welding symbol, what does a circle at the junction of the arrow and the reference line indicate?

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Why the flag matters

The flag splits the work between two crews and two places. The shop leaves those joints unwelded so the parts can be fitted together on site. The erector plans equipment, access, positions and inspection for every flagged weld. Field welds are often made out of position, at height and in the weather, so they tend to get extra attention at inspection time. For an inspector, the flags on a drawing are a quick list of the welds that will be checked on site rather than in the shop.

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Common mix-ups

  • The flag is not a note. It sits at the arrow bend, not at the tail. Notes, processes and specifications go in the tail.
  • Field weld or welding position. The flag says where the weld is made, not how. It doesn't mean overhead or vertical. The position comes from the joint as it will sit on site.
  • Flag and circle are separate marks. Either can appear without the other. Read each one on its own, then together.
  • A missing flag. No flag means a shop weld. A weld that has to be made after erection but isn't flagged is a drawing question to raise, not a guess to make.

On the CWI exam

The flag is one of the supplementary marks under Symbols, Welding and NDE, at least 10% of CWI Part A and read from memory, since Part A is closed book. Part B drawings use it too, under Utilization of Specifications and Drawings, at least 8% of that practical exam.

Practice it

Add and remove the flag in the welding symbol builder and read what changes in the plain-words result. Look it up next to the other supplementary marks on the welding symbols chart, and see how it sits on the most common weld of all on the fillet weld symbol page.

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Facts checked 24 October 2026 against the sources listed above. If something has changed, tell us and we will correct it within 2 business days.

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