In a groove weld, what determines when to stop filling and finish with throat thickness?

• A. After the first root pass.
• B. As soon as you run out of filler metal.
• C. When the final throat thickness is reached.
• D. When color changes.

Answer: (C)

In a groove weld, the amount of metal you deposit is guided by the required throat thickness from the joint design. The throat is the narrowest distance through the weld cross-section, from the root up to the face of the weld. You fill the groove with a root pass and then additional filler passes until the weld reaches the specified throat thickness. Once that thickness is achieved, you stop filling and finish the weld to preserve the designed weld size and prevent excess reinforcement that could cause distortion or other issues. The other factors—whether you’ve finished the root pass, running out of filler metal, or a color change—don’t determine when the weld is finished in terms of meeting the design throat thickness.