Convex contour
Applied to joint
Supplementary symbol applied to fillet weld
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Description
A supplementary symbol indicating that the weld face is to be left with or finished to a convex (crowned, raised) profile. The weld has extra material above the surface plane.
In plain English
The weld face is left with a crown -- it bulges out above the plate surface. A curved line (dome side up) across the weld symbol means 'convex finish'. This is the natural profile of most welds, so specifying convex often just means 'leave it as-welded, do not grind'. In some cases, convex is specifically required because the extra throat provides a safety margin. However, for fatigue, convex is worse than flush because the sharp transition at the toes creates stress concentration.
Symbol position
Convex curve drawn across the top of the weld symbol.
Size notation
No additional dimensions for the contour itself.
Common uses
- General structural welds where as-welded profile is acceptable
- Welds where extra throat provides safety margin
- Non-fatigue-critical joints
- Pressure containing welds (extra material at surface)
