What is a root pass in a groove weld?

What is a root pass in a groove weld?

• A. The final finishing pass to shape the weld
• B. The initial weld bead that establishes the root and penetration in the joint
• C. The filler metal deposit placed after the root is formed
• D. A test bead used to check alignment

Answer: (B)

In groove welding, the root pass is the first weld bead laid along the bottom of the groove to fuse the two pieces at the root and establish penetration through the joint. This initial pass creates the essential fusion line at the root, setting the foundation for the rest of the weld. If the root isn’t properly fused and penetrated, the joint can be weak or fail to hold, no matter how the subsequent passes are applied. The remaining passes—filler passes to fill the groove and a cap pass to finish and reinforce the weld—build on this root, but they don’t replace the importance of that first root bead. It’s not the final finishing pass, not a separate filler deposit after the root, and not a test bead for alignment.

In groove welding, the root pass is the first weld bead laid along the bottom of the groove to fuse the two pieces at the root and establish penetration through the joint. This initial pass creates the essential fusion line at the root, setting the foundation for the rest of the weld. If the root isn’t properly fused and penetrated, the joint can be weak or fail to hold, no matter how the subsequent passes are applied. The remaining passes—filler passes to fill the groove and a cap pass to finish and reinforce the weld—build on this root, but they don’t replace the importance of that first root bead. It’s not the final finishing pass, not a separate filler deposit after the root, and not a test bead for alignment.