Plug welding in collision repair is used to:

• A. Attach Trim Pieces
• B. Replace Factory Spot Welds When Resistance Welding Is Not Possible
• C. Seal Panels With Sealant
• D. Weld a Seam Without Holes

Answer: (B)

Plug welding is a method for joining two overlapping metal panels by welding through holes in the upper panel into the lower one. In collision repair, its main use is to replace factory spot welds when resistance welding isn’t possible. When a patch or replacement panel must be fastened where you can’t reach the backside to create traditional spot welds, drilling holes and welding through them lets you mimic the spot weld pattern and restore the panel’s strength and rigidity.

Think of it as recreating the function of the original spot welds in a situation where the normal welding process can’t be used. The holes control heat and allow the weld to fuse the two pieces together evenly, producing small round welds on the surface.

This isn’t about attaching trim pieces, sealing with sealant, or welding a seam without holes. Those tasks use different methods or processes, whereas plug welding specifically aims to reproduce spot welds by welding through drilled holes.