§1.2B · Under Welding and NDE symbols
How to read a fillet weld symbol on the CWI
The fillet weld symbol is a small right triangle on the reference line, with its vertical leg always drawn on the left. The weld size goes to the left of the triangle, length and pitch go to its right, and the side of the line it sits on tells you which side of the joint gets welded.
- Exam
- CWI
- Clause
- §1.2B
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- 7
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- Welding and NDE symbols
1.2B.1Reading it from the arrow out
Start where the arrow meets the reference line. That's where the extras sit: a circle for weld-all-around, a flag for a field weld. The flag can point either way; its direction carries no meaning.
Next, the side. A triangle hanging below the line is an arrow-side weld. One standing above the line is an other-side weld. One on each side means both sides of the joint get a fillet. The arrow can point left, right, up or down, and none of that changes the rule.
Then the numbers. For an equal-leg fillet the size is the leg. An unequal-leg fillet shows both legs, and the drawing has to show which leg goes on which member. After the triangle comes length, then a dash, then pitch for intermittent welds. No length means the weld runs the full length of the joint.
Contour and tail
A contour symbol over the triangle (flat, convex or concave) with a finish letter tells you how the face is finished. Under A2.4:2020 the flat contour symbol is kept for fillets only. The tail carries a process, a WPS number or a note. When there's nothing to reference, the tail is left off.
What the size number means when you put a gauge on the weld is a separate question, answered on fillet size vs throat. Groove welds read differently: see groove weld symbols. Supplementary symbols and NDE symbols are in the welding and NDE symbols clause.
1.2B.2One symbol, every slot filled
1.2B.3Reading examples
| On the symbol | Side | Means | Easy misread |
|---|---|---|---|
| 5/16, nothing to the right | Arrow side | 5/16 in fillet, full length of the joint | Treating a missing length as optional |
| 3/8 2-6 below the line | Arrow side | 3/8 in fillet in 2 in segments, centers 6 in apart | Reading 6 as the gap. The clear gap is 4 in |
| Two triangles lined up, 1/4 3-12 on each | Both sides, chain | Segments sit directly across from each other | Calling it staggered |
| Concave contour over the triangle, letter G | As drawn | Concave face, finished by grinding | Ignoring the finish letter |
| Two numbers on the left, 1/4 x 3/8 | As drawn | Unequal-leg fillet; the drawing shows which leg goes where | Assuming the bigger leg goes on the vertical member |
Inch examples for illustration. Metric drawings follow the same layout.
1.2B.4Words that go with the symbol
- Reference line
- The horizontal line every element hangs from. It always reads left to right.
- Arrow side / other side
- The side of the joint the arrow touches, and the side opposite it.
- Pitch
- Center-to-center spacing of intermittent segments. It's never the gap between them.
- Chain vs staggered
- Chain segments line up across the joint, pair by pair. Staggered segments take turns, one side and then the other.
- Field weld
- A weld made at the erection site rather than in the shop, marked by the flag.
1.2B.5Read the symbol
Symbols described in words, the way a foreman might read one off a print.
0 of 7 tagged · 0 accepted
Tag 01
In a welding symbol, where is the size of a fillet weld shown?
Remarks on every option
- A Above the line means the weld goes on the other side. The size number sits beside the symbol, on whichever side the symbol is.
- B Correct: The fillet size (leg) is written to the left of the weld symbol, on the same side of the reference line as the symbol.
- C Right of the symbol is for length and pitch (center-to-center spacing) of the weld, not its size.
- D The tail holds references like a process, specification or note. Dimensions stay with the weld symbol.
Pick an option. The remarks on all 4 open here.
Tag 02
When a fillet weld symbol shows (8-16), what does this indicate?
Remarks on every option
- A Size goes to the left of the weld symbol. The pair on the right is length and pitch.
- B Reversed. The first number is segment length; the second is pitch.
- C Correct: 8-16 means 8-unit segments at a 16-unit pitch. Pitch is center-to-center, so the clear gap is 8 units.
- D Welding symbols don't show pass count or travel angle that way.
Pick an option. The remarks on all 4 open here.
Tag 03
How is a staggered fillet weld indicated on opposite sides of a joint?
Remarks on every option
- A There's no crossed symbol for this. Staggered welds use symbols on both sides of the reference line, offset.
- B Correct: Fillet symbols go on both sides of the reference line, offset from each other, with length-pitch for each side.
- C Separate arrows aren't needed. Both sides go on one reference line.
- D A symbol on one side calls for welds on that side only. Staggered welds need both.
Pick an option. The remarks on all 4 open here.
Tag 04
What does a chain intermittent fillet weld symbol indicate?
Remarks on every option
- A Chain intermittent welds are on both sides. One side only is a plain intermittent weld.
- B Continuous welds have no length-pitch. Chain welds are intermittent.
- C Offset segments are staggered intermittent welds, the other arrangement.
- D Correct: Chain intermittent welds sit directly opposite each other on both sides of the joint. Staggered welds are offset.
Pick an option. The remarks on all 4 open here.
Tag 05
How is a weld-all-around requirement shown when combined with a fillet weld symbol?
Remarks on every option
- A A circle on the reference line reads as a spot or seam weld symbol, not weld-all-around.
- B Correct: The weld-all-around circle goes at the junction of the arrow and the reference line.
- C The tail carries specs, process or notes. Weld-all-around doesn't go there.
- D A circle stacked on the weld symbol isn't a convention. All-around goes at the arrow junction.
Pick an option. The remarks on all 4 open here.
Tag 06
What does the placement of a weld symbol below the reference line indicate?
Remarks on every option
- A Other side is shown above the reference line.
- B Correct: Below the reference line means arrow side, whichever way the arrow points.
- C Both sides need symbols above and below the line.
- D Placement does mean something: below is arrow side, above is other side.
Pick an option. The remarks on all 4 open here.
Tag 07
How is a combination of different size fillet welds on opposite sides shown?
Remarks on every option
- A A size on one side covers that side only. Each side's weld gets its own size.
- B Sizes go to the left of each weld symbol, not in the tail.
- C Showing the larger size on both sides calls for the wrong weld on the smaller side.
- D Correct: Each side's fillet symbol carries its own size to its left, so different sizes just show different numbers above and below the line.
Pick an option. The remarks on all 4 open here.
1.2B.6Odd corners of the symbol
Why is the vertical leg of the triangle always on the left?
It's the A2.4 drawing convention. The triangle is drawn the same way whatever the joint looks like, so it doesn't tell you which member is vertical. The drawing view does that.
Is there a fillet weld symbol chart worth memorizing?
Memorize the layout instead: extras at the arrow junction, side by the reference line, size on the left, length and pitch on the right, notes in the tail. The full set is in AWS A2.4:2020, still the current edition (checked October 2026).
What does a concave fillet weld symbol mean?
A concave contour symbol over the triangle means the face is to be concave, and a finish letter says how to get it there. A concave face carries less throat than its leg suggests: see fillet size vs throat.
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