Preferred for thick materials because it allows for better penetration and heat control.

| Position | Groove Weld | Fillet Weld | |----------|-------------|--------------| | Flat | | 1F | | Horizontal | 2G | 2F | | Vertical | 3G | 3F | | Overhead | 4G | 4F |

The weld is made on a vertical surface, moving either upwards (Vertical Up) or downwards (Vertical Down).