03 Drawings and welding symbols · 16 min
The welding symbol, piece by piece
Reference line, arrow, tail. Below = arrow side. Above = other side. Triangle vertical leg always on the left.
Canadian shop drawings for structural steel use AWS A2.4-style welding symbols (CSA W59 points you at the symbol standard). ISO 2553 is a different language — do not mix them on exam day. In AWS, the weld symbol below the reference line is the arrow side. The symbol above the line is the other side.
| Element | Job |
|---|---|
| Reference line | Horizontal backbone. Required. |
| Arrow | Points at the joint. Required. A break in the arrow shaft points at the member to be prepared (bevel/J/U). |
| Tail | Process, WPS, spec, electrode. Omit the tail if you have nothing to say. |
| Weld symbol | The little glyph: fillet triangle, V, bevel, plug, etc. |
| All-around | Circle at the junction of arrow and reference line. Weld all around the joint. |
| Field weld | Flag at that same junction. Made on site, not in the shop. |
| Melt-through | Filled semicircle on the other side of a CJP from the welded side. |
| Contour | Flat / convex / concave arc plus a finish letter (G grind, C chip, M machine, H hammer, R roll, U unspecified). |
Where the numbers live
- Fillet size: left of the triangle. Unequal legs show both, e.g. 6 × 10, with the first number corresponding to the vertical (left) leg.
- Length–pitch: right of the triangle, written length–pitch (50–100). Pitch is centre-to-centre, not the gap.
- Groove angle: inside the groove glyph. Root opening sits along the reference line at the glyph.
- Depth of bevel / specified throat: left of a groove glyph. (S) or similar notes may flag effective throat — read the tail and the drawing notes.
- Plug diameter or slot width: left of the plug glyph. Angle of countersink and depth of filling as specified. Pitch to the right.
- Multiple reference lines: the one nearest the arrow is the first operation. Subsequent lines are later operations (back weld, NDT, etc.).