When plug welding three pieces, how should the hole in the top piece compare to the hole in the middle piece?

When plug welding three pieces, how should the hole in the top piece compare to the hole in the middle piece?

• A. Smaller
• B. Same size
• C. Larger
• D. Not specified

Answer: (C)

When plug welding multiple sheets, you want the molten weld metal to flow through the stack and fuse all layers. Making the hole in the top sheet larger than the hole in the middle piece provides enough through-thickness access for the weld to penetrate and create a solid plug that ties the top, middle, and bottom pieces together. If the holes were the same size, penetration might be insufficient and fusion weak; if the top hole were smaller, there wouldn’t be enough clearance for the weld metal to fill through the layers. The smaller middle-hole helps control the weld metal distribution so you get a proper plug without excessive buildup in the middle layer.

When plug welding multiple sheets, you want the molten weld metal to flow through the stack and fuse all layers. Making the hole in the top sheet larger than the hole in the middle piece provides enough through-thickness access for the weld to penetrate and create a solid plug that ties the top, middle, and bottom pieces together. If the holes were the same size, penetration might be insufficient and fusion weak; if the top hole were smaller, there wouldn’t be enough clearance for the weld metal to fill through the layers. The smaller middle-hole helps control the weld metal distribution so you get a proper plug without excessive buildup in the middle layer.