Joint Preparation, Fit-Up, and Welding Symbols
This domain tests joint preparation, fit-up and welding symbols: joint types, groove geometry, root gap and land, tacking, alignment, and reading a symbol on a drawing. The exam expects you to translate a symbol into the actual weld.
Core rules
- Common joints are butt, lap, T, corner and edge. Groove preparations include square, single-V, double-V, U and J.
- Root gap is the space between members; root face (land) is the unwelded thickness at the root; bevel angle is the angle of one prepared edge.
- Clean surfaces, control alignment, and place tack welds where they will be fused or removed as specified.
- On a welding symbol, the arrow points to the joint; the reference line carries the symbol. A symbol below the line is on the arrow side; above the line is on the other side.
Worked example
A drawing shows a fillet symbol below the reference line, 6 on the left, 75-150 on the right, a circle at the reference-line junction and a flag in the tail. Reasoning: 6 is the fillet size in mm; 75 is the weld length and 150 is the pitch, so it is an intermittent fillet; below the line means arrow side; the circle means all around; the flag means field weld. The welder should make 6 mm fillets, 75 mm long, spaced at 150 mm centres, all around the part, on site.
Traps
Do not assume a dimension is drawn to scale. Do not confuse bevel angle with included angle. Do not read a symbol above the line as arrow side. Do not ignore root gap or land; both change penetration and burn-through.