“So the weld’s axis is horizontal,” Lou said. “Even though you’re welding on top, that’s not a flat position weld. That’s horizontal position—because the pipe’s centerline runs side to side. If you weld it like a flat plate, gravity’s going to pull your puddle down the side before you can say ‘undercut.’”
The lesson Marco never forgot: Welding on top of a horizontal pipe is horizontal position welding (per AWS: 2F for fillet, 2G for groove)—and it requires deliberate technique to manage gravity’s sideways pull. Ignore that, and your weld will sag, undercut, or fail when it matters most. Takeaway for your own work: When you see a horizontal joint (the weld’s length runs left-to-right), always remember—gravity is not your friend. Aim slightly upward, keep a tight arc, and watch the puddle’s lower edge like a hawk. That small adjustment separates a pretty weld from a safe weld. horizontal position in welding
Here’s a useful story that illustrates the importance of the in welding, specifically for safety and quality. Title: The Pipe that Almost Rolled “So the weld’s axis is horizontal,” Lou said
Marco shrugged. He’d done flat welds before. He struck an arc. If you weld it like a flat plate,