⌒ Convex weld contour
Convex weld contour · Soldadura en plano · ISO 1101 + ASME Y14.5
Example in plan
How to interpret it
On the drawing, “△ with convex contour specified” states a convex weld contour requirement.
What controls
Contour symbol requiring the weld face to bulge outward relative to the line joining its toes. On fillet welds, convexity is excess material over the theoretical cross-section: it adds metal but does not increase the effective throat, which is still measured from the root. The symbol calls for a shape; the size is still the one given by the weld dimension and is not replaced by the crown.
How to verify
Weld gauge with a convexity step placed on the bead, or a leg-length gauge to confirm the theoretical section is met regardless of the crown. Visually, check the transition into the plate: it must be continuous, with no ledge or notch at the toe. On critical welds, excessive convexity is recorded as an observation even when the size is correct.
Common mistakes when interpreting it
- Believing a more crowned bead is a stronger bead: the throat is measured from the root and excess face metal does not count.
- Accepting abrupt transitions at the weld toe because there is plenty of metal.
- Confusing convexity with the reinforcement of a groove weld: they are different welds with different criteria.
How to get it in the workshop / if it comes out of tolerance
A convex bead comes from more filler or lower travel speed, and it is the natural result in many welding positions. The practical limit is twofold: too much convexity creates a sharp re-entrant angle with the plate where stresses concentrate and dirt collects, and it wastes metal that adds no strength. If the drawing calls for convex, keep it smooth with no abrupt transition into the plate.
Excessive convexity: increase travel speed or reduce filler, and review the position; when welding vertical-up the puddle tends to pile up. If undercut appears at the toe along with the convexity, the problem is electrode angle and heat input, and that is a real defect to correct. Do not fix it by grinding the crown of the bead without re-checking the throat afterward.
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