What is a root gap?

What is a root gap?

• A. The distance between the two pieces of a groove weld at the bottom of a joint
• B. The distance between the top of two plates
• C. The buildup of filler metal at the root
• D. The gap between the weld and the base metal undercut

Answer: (A)

The root gap is the space between the root faces of the two pieces at the bottom of a groove weld—the distance the weld metal must fill to fuse the joint at its root. This gap is what allows proper access and penetration to join the pieces together at the root, which is crucial for a sound weld, especially in groove welds. The top surface distance between plates isn’t the root gap, and the buildup of filler metal at the root describes the weld bead or reinforcement, not the gap itself. The gap at the base metal undercut refers to a defect where metal is removed along the edge, not the spacing between pieces at the root.

The root gap is the space between the root faces of the two pieces at the bottom of a groove weld—the distance the weld metal must fill to fuse the joint at its root. This gap is what allows proper access and penetration to join the pieces together at the root, which is crucial for a sound weld, especially in groove welds. The top surface distance between plates isn’t the root gap, and the buildup of filler metal at the root describes the weld bead or reinforcement, not the gap itself. The gap at the base metal undercut refers to a defect where metal is removed along the edge, not the spacing between pieces at the root.