NEW TACK-WELDING INTEGRATION PAYS OFF FOR OIL AND GAS PIPE MAKER
Adding the Power Wave® AC/DC 1000 SD from Lincoln Electric allows United Spiral Pipe to nearly double line speed, while boosting quality
"Tack welding is a common bottleneck in both longitudinal and spiral pipe mill production all over the world... United Spiral Pipe raised the bar for spiral tacking speeds.”
Each day, fabrication crews at United Spiral Pipe LLC are charged with one task: to produce high-quality, large-diameter, helical-submerged-arc-welded (SAWH) spiral pipe for the oil and gas industry. And they do just that – at record-breaking speeds.
The Pittsburg, Calif.-based pipe mill, a joint-venture between U.S. Steel, SeAH and POSCO, uses an advanced automated two-step welding process that is capable of producing 300,000 net tons of line pipe per year. Outside diameters of produced spiral pipe range from 24 to 64 inches, using A252- through X80-grade steel with wall thicknesses from ¼ to 1 inch. The process consists of one forming and three welding lines.
Two-Stepping through Production
Two-step spiral SAWH-pipe fabrication begins with forming, tack welding and cutting. Hot-band coils unwind on a mandrel and feed into an edge miller that cuts and prepares strip edges for the tack welding process. The feed angle depends on strip width and final outside diameter. From there, the pipe is formed into the proper diameter and tack welded via a large-wire gas-metal-arc-welding (GMAW) process and cut in lengths from 40 to 80 feet.
The second step of the welding process sends the tack-welded pipe into one of three final welding stations. Here, the pipe’s tack-welded seam is re-welded using SAWH to fully meet API 5L standards and customer requirements.
Welding Speed Nearly Doubled
Upfront during initial tack welding is where the mill has gained true speed and efficiency – with measurable quality improvements. Welding speeds have nearly doubled at the tacking station via a unique setup using the PowerWave® AC/DC 1000® SD power source from Lincoln Electric and integration through Uhrhan & Schwill GmbH, a Lincoln Electric subsidiary. Learn More