Weld symbol
Stud weld symbol
A circle crossed through calls for stud welding: a threaded or headed stud fused end-on to a surface in a single arc or resistance cycle, always on the arrow side.
Reads as: Arrow side: stud weld, 3/4 size, 12 pitch, 12 welds.
How to read it
The stud weld symbol is a circle with an X drawn through it. It describes a process rather than a joint geometry: a stud is held against the workpiece, an arc or a current pulse melts both mating faces, and the stud is plunged into the molten pool to fuse end-on to the surface. There is no groove and no fillet to dimension.
Because a stud is placed onto a surface rather than into a joint between two members, the symbol is always drawn on the arrow side of the reference line. There is no meaningful other side: the stud goes where the arrow points, on the face the arrow touches. Seeing this symbol above the line is a drafting error rather than an alternative reading.
The number to the left is the stud's diameter, and a count in parentheses says how many. A pitch to the right gives the centre-to-centre spacing where the studs run in an evenly spaced line, which is exactly how shear connectors are called out along a composite beam. Complex layouts are dimensioned on the drawing instead.
Stud welding's quality shows up at the collar of expelled metal around the base. A complete, even collar all the way round suggests the arc and plunge were right; a partial or missing collar on one side suggests the stud was not perpendicular or the arc was short. That is why bend testing a sample of studs is such a common acceptance step on shear connector work.
Where each dimension goes
- Stud diameter (left of the symbol)
- Shank diameter of the stud being welded to the surface.
- Count (in parentheses)
- How many studs the callout covers.
- Pitch (right of the symbol)
- Centre-to-centre spacing along a line of studs, as on shear connectors down a beam.
- Arrow side only
- The symbol always sits below the reference line, because a stud is placed on the surface the arrow touches.
Worked examples
Shear connectors along a beam
“Weld twenty 3/4 diameter studs at twelve-inch centres along the top flange.”
The 3/4 is the stud shank diameter, the parenthesised count is how many, and the twelve-inch pitch spaces them down the flange as composite shear connectors.
Small studs in a tight pattern
“Attach eight 1/4 diameter studs on three-inch centres to the arrow-side face.”
The symbol sits below the reference line because a stud is always welded to the surface the arrow touches, and the count and pitch define the row on that face.
Common mistakes
- Drawing or reading the stud symbol on the other side of the reference line, which has no meaning here.
- Treating the diameter to the left as a weld size rather than the stud's shank diameter.
- Ignoring the collar of expelled metal when judging whether the weld went down properly.
- Laying out studs by eye when a pitch is given, which throws off the whole connector spacing.
Typical joints
Related symbols
Practise reading welds, not just symbols
The drawing tells you what the weld should be. The gauge trainer is where you find out whether you can tell what it actually is.