When making a vertical butt weld, from which end should the weld be started?

When making a vertical butt weld, from which end should the weld be started?

• A. Left
• B. Top
• C. Bottom
• D. Right

Answer: (B)

Gravity affects molten metal in a vertical weld, so starting at the top end of the joint and progressing downward gives you the best control over the weld pool. Beginning at the top allows gravity to help keep the molten metal within the joint as you move down, helping maintain a uniform bead, good root penetration, and reducing the tendency for the metal to sag, run off, or crater at the start. If you began at the bottom and moved upward, gravity would pull the molten metal away from the joint as you progress, making it harder to keep the pool in place and increasing the risk of poor fusion or sagging. So, start from the top end.

Gravity affects molten metal in a vertical weld, so starting at the top end of the joint and progressing downward gives you the best control over the weld pool. Beginning at the top allows gravity to help keep the molten metal within the joint as you move down, helping maintain a uniform bead, good root penetration, and reducing the tendency for the metal to sag, run off, or crater at the start. If you began at the bottom and moved upward, gravity would pull the molten metal away from the joint as you progress, making it harder to keep the pool in place and increasing the risk of poor fusion or sagging. So, start from the top end.