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What does this kind of welding symbol indicate? I can see that it is a field weld, all around, with flat finish but the two vertical lines are not known to me. I found it in a drawing of a steel railing. What kind of weld is this, and how is it made?


2 Answers 2


The vertical lines show the edge preparation of the join. Since they are both vertical, then both plates (pipes, tubes, etc.) are squared off. There are no bevels. It is technically as "square groove".

All of the standard weld symbols are given in an American Welding Society (AWS) chart.

  • $\begingroup$ Interesting, I thought all welds need a bevel or fillet. Where does the molten electrode material go in this kind of weld since there is no bevel for it, nor a place for a fillet? Also, there is no size indicated for this weld, how is its strenght determined? $\endgroup$
    – S. Rotos
    Commented Feb 23, 2022 at 12:57
  • $\begingroup$ @S.Rotos so you need to get the puddle deep enough, too shallow and it looks like chicken shit with no strengh, too deep and you blow holes. Worth getting some practice: gas, arc then mig & tig. $\endgroup$
    – Solar Mike
    Commented Feb 23, 2022 at 18:38
  • $\begingroup$ @S.Rotos This type of weld would be a full penetration weld, so the size doesn't really mean anything. The gap between pieces would be big enough to to get weld metal all the way to the root. It would also likely involve a backer material like other one sided full penetration welds. $\endgroup$
    – hazzey
    Commented Feb 23, 2022 at 23:30

This is square groove all around site weld joint. The circle at the arrow and reference line intersection means all around. The flag means Field Weld joint. 2 vertical lines means a square groove. The final weld finish is flush shown by horizontal line placed on the weld symbol. This is a helpful article to learn Welding Symbols in depth.


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