What is a butt joint, and what edge preparation might it require for a full-penetration weld?

What is a butt joint, and what edge preparation might it require for a full-penetration weld?

• A. Two pieces joined edge-to-edge; edges may be square or beveled to suit thickness for full penetration.
• B. Two pieces overlapped with a fillet weld.
• C. A joint formed by overlapping with a lap.
• D. Edge-to-edge butt joint with no weld.

Answer: (A)

A butt joint is when two pieces are placed in the same plane and joined along their edges, edge-to-edge. For a weld to be a full-penetration weld, the weld metal must fuse all the thickness of the joint. If the edges are simply square, achieving that full depth can be challenging on thicker pieces and may require more heat or multiple passes. To make full penetration easier and more reliable, the edges are often beveled to create a groove (such as a V, U, or J groove). This beveling opens up the joint so the weld can reach the root and fuse through the entire thickness. The exact edge shape and bevel angle depend on the plate thickness and the welding process being used.

A butt joint is when two pieces are placed in the same plane and joined along their edges, edge-to-edge. For a weld to be a full-penetration weld, the weld metal must fuse all the thickness of the joint. If the edges are simply square, achieving that full depth can be challenging on thicker pieces and may require more heat or multiple passes. To make full penetration easier and more reliable, the edges are often beveled to create a groove (such as a V, U, or J groove). This beveling opens up the joint so the weld can reach the root and fuse through the entire thickness. The exact edge shape and bevel angle depend on the plate thickness and the welding process being used.