Butt, lap, fillet (T), corner and edge joints, and the parts of a weld.
A weld joint is the way two pieces are placed and welded together. The joint is chosen according to the shape of parts, the load and the thickness.
Basic joints
| Joint | Arrangement | Use |
|---|---|---|
| Butt joint | Edges placed in line, end to end | Plates, pipes – strong joint; thick plates need edge preparation (V, U, J) |
| Lap joint | One plate overlaps the other; welded with fillet | Sheet metal, repair work |
| Tee (T) joint | One plate at 90° on another; fillet weld | Frames, brackets, stiffeners |
| Corner joint | Edges meet at a corner (L shape) | Boxes, frames |
| Edge joint | Two edges placed side by side | Thin sheets |
Fillet weld
A weld of roughly triangular section joining two surfaces at right angles (in lap, T and corner joints). Its size is given by the leg length.
Parts of a weld
- Face – exposed surface of the weld.
- Root – deepest point of the weld.
- Toe – where the weld face meets the base metal.
- Reinforcement – weld metal above the plate surface.
- Penetration – depth to which the base metal is fused.
Quick Revision
- Five joints: butt, lap, T, corner, edge.
- Fillet weld in lap, T and corner joints; size = leg length.
- Thick plate butt joints need V/U edge preparation.
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