Marco shrugged. He’d done flat welds before. He struck an arc.
His journeyman, Lou, was a quiet veteran with 30 years of experience. Lou looked at Marco’s setup and asked, “What position are you using?” horizontal position in welding
Marco ground out his mess and tried again. This time, he tilted the electrode 5–10 degrees upward, kept a tight arc, and moved steadily. He watched the puddle solidify like a tiny shelf, each ripple locking in place before the next. The weld was flat on top, slightly convex on the bottom face, and fully fused. Marco shrugged
“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.’” His journeyman, Lou, was a quiet veteran with
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.