Full penetration butt weld

The thickness of weld reinforcement is based on the thickness of the thinner of the materials being joined. Thus, workpieces are nearly parallel and do not overlap, unlike lap joints, for example. With the conventional fusion welding processes of TIG and MIG penetration of weld metal into the surface of a flat plate from a bead-on-plate run is typically 3 mm and 6 mm respectively. For heavier applications filler metal is added to melt or fuse the edge completely and to reinforce the plate. Another example of a full penetration weld is this: The weld symbol depicts a single bevel v groove weld that is full penetration. The weld symbol for a full penetration weld could look something like this.

Shops that specialize in this type of metal work are called fab shops. Welds can be geometrically prepared in many different ways. Many design specifications will also have lower allowable stresses for a fillet weld compared with a butt weld and this can have a significant effect on cost, particularly when designing to match the strength of thicker plates.