Slot Weld Symbol
How to read a slot weld symbol — width, length, depth of filling, countersink angle, and pitch. How to distinguish it from a plug weld, and D1.1:2025 spacing requirements.
Slot Weld Symbol Dimensions
Per AWS A2.4 §10, slot weld dimensions follow the same side-of-reference-line rule as all weld symbols. All dimensions appear on the same side as the symbol.
Where Each Dimension Goes
Width — to the LEFT of the symbol. No Ø prefix (that is the plug weld identifier).
Length — to the RIGHT of the symbol.
Depth of filling — INSIDE the rectangle. Omission means complete fill.
Countersink angle — above or below the symbol.
Pitch — to the RIGHT, in length-pitch format for multiple slots.
Number of slot welds — in parentheses.
Slot Weld Requirements
D1.1 §4.11.2 governs slot weld spacing. Like plug welds, slot welds are prohibited in certain high-strength steels.
| Requirement | Value | Source |
|---|---|---|
| Min transverse spacing | 4 × slot width (center-to-center) | §4.11.2 |
| Min longitudinal spacing | 2 × slot length (center-to-center) | §4.11.2 |
| Q&T restriction | Prohibited in steels with Fy > 70 ksi | §4.11.4 |
| Technique | Position-specific per §7.24 | §7.24 |