What is the purpose of tack welds, and where are they typically placed?

• A. To hold components in alignment during welding; placed at ends and intermediate points to prevent distortion.
• B. To permanently join components.
• C. To test weld quality.
• D. To remove excess material.

Answer: (A)

Tack welds are temporary welds used to hold parts in the correct position before the final weld is made. Their main job is to keep the joint aligned and the gaps consistent while heat from welding can cause movement or distortion. Placing tack welds at the ends of a joint and at intermediate points along its length helps lock the geometry in place: the ends prevent corners from shifting, and the intermediate points keep the long seam from bowing or pulling out of alignment as heat is applied along the weld. Because they’re meant for alignment rather than permanent strength, tack welds are quick, small welds that can be removed or welded over as you complete the final weld.