LA City Certified Welder Written Practice Test

In a groove weld, the total included angle is the angle formed inside the groove between the two bevel faces. For a full-penetration butt weld on carbon steel, you want enough opening to allow the weld metal to fuse through the entire thickness and reach the root reliably. A wide V groove, about 60 degrees on each side, gives a total included angle of around 120 degrees. This wide opening improves access for the electrode, helps achieve full fusion at the root, and accommodates the filler metal needed to fill the groove and reach full penetration, especially with common welding heat inputs and plate thicknesses.

Smaller groove angles (for example, a narrow V) can be harder to fully penetrate on thicker plates because the heat and filler must travel a shorter path to the root, increasing the risk of incomplete fusion. While exact numbers can vary with plate thickness and welding process, the typical practice for full-penetration carbon steel welds is around a 120-degree total angle.