Marco was a second-year welding apprentice working on a water treatment plant upgrade. His task: weld a support bracket onto a 12-inch horizontal steel pipe that carried non-potable water. The pipe was stationary, about chest-high, and the weld was a simple fillet—a perfect opportunity to practice.
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
Later, the bracket held a heavy pump during a pressure test. No cracks, no leaks. Marco was a second-year welding apprentice working on
Within three inches, his molten puddle sagged. The top bead looked fine, but the toe on the lower side was jagged—metal had dripped downward before solidifying. He tried speeding up, but that just created cold lap. Frustrated, he chipped off the slag and saw the truth: a weak, uneven weld with undercut along the bottom edge. His journeyman, Lou, was a quiet veteran with
“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.’”