Concave contour symbol
Also called Concave finish
An arc bulging towards the weld symbol means the finished weld face is concave, usually on fillet welds for a smooth transition.
What the concave contour symbol means
An arc bulging towards the weld symbol means the finished weld face is concave, usually on fillet welds for a smooth transition.
AWS A2.4 and ISO symbols
Where you see it
Fatigue-loaded fillet welds, where a smooth transition from weld to plate lowers the stress at the toe.
How it is inspected
Inspection of a concave contour usually covers visual inspection of the profile, and a check that the throat is still at least the size on the drawing. Each inspection is recorded against the weld, so the joint can be signed off with its evidence. See the ITR guide.
Related symbols
Frequently asked questions
What does the concave contour symbol look like?
On AWS A2.4 drawings: An arc beyond the weld symbol, curving towards it. In ISO 2553: The same arc.
Is the concave contour symbol the same in ISO and AWS?
No. The same arc.
Where is a concave contour used?
Fatigue-loaded fillet welds, where a smooth transition from weld to plate lowers the stress at the toe.
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