What is fall through in welding terms?

What is fall through in welding terms?

• A. A localized area of excessive penetration
• B. A gap in the weld
• C. A lack of fusion
• D. An undercut

Answer: (A)

Fall through is a weld defect where heat and molten metal penetrate so deeply that they pass through the joint and into the opposite side, often leaving a through-thickness hole or burn-through in a localized area. This is essentially excessive penetration in one spot, not a gap, not a lack of fusion, and not an undercut. It happens when heat input is too high or the procedure allows the weld to over-penetrate, so controlling heat, travel speed, and joint setup helps prevent it.