03 Drawings and welding symbols · 14 min
Glyphs you must recognise instantly
Fillet, square, V, bevel, U, J, flare, plug, spot, seam, surfacing, backing, melt-through.
| Glyph | Means | Watch-out |
|---|---|---|
| Right triangle | Fillet | Vertical leg on the left, always |
| Two parallel lines (square) | Square groove | Root opening dimension sits at the glyph |
| V | V-groove, both members prepared | Included angle inside the V |
| Half-V / bevel | Bevel groove, one member prepared | Broken arrow points at the prepared piece |
| U / J | U-groove / J-groove | J is one-member; U is both |
| Flare-V / flare-bevel | Weld in the pocket of a round or bent member | Size is the remaining gap after welding unless specified |
| Rectangle (plug/slot) | Plug or slot | Slot is shown with length; plug is diameter |
| Circle (spot) | Spot weld | Size is diameter; process often in the tail (RSW, GMAW) |
| Circle on both sides of line (seam) | Seam weld | Strength or width as specified |
| Two opposing arcs (surfacing) | Build-up / surfacing | Height of overlay to the left; length to the right |
| Rectangle on the opposite side (backing) | Backing bar or backing weld | Read the tail: MB metal backing, R remove, etc. |
| Filled half-circle | Melt-through | Other side of a CJP welded from one side |
Intermittent fillets
Chain intermittent: both-side fillets line up. Staggered intermittent: they are offset. AWS shows stagger by offsetting the triangles along the reference line. Pitch is centre to centre of increments on the same side. Do not confuse pitch with the unwelded gap.