Wind Tower Welding: Lattice Masts to ABB Robots

A modern wind turbine stands on a steel tube that is often more than 100 metres tall, and offshore it sits on a monopile that can weigh 2,000 tonnes. Nearly all of that steel is joined by welding, so wind tower welding sets the pace for how fast the industry can build. This post traces the work from lattice masts to the submerged arc lines that make tower sections and monopiles today, looks at new monopile plants in Japan and Germany, and explains where ABB welding robots could fit and which jobs are still done by hand.

Welding a wind turbine tower section at Enercon Windtower Production in Malmö, Sweden, 2014. Photo: Johan Wessman / News Oresund via Wikimedia Commons (CC BY 2.0)

From lattice masts to submerged arc seams

Early wind turbines stood on lattice towers built from steel members, much like electricity pylons. The best known is the Smith-Putnam turbine, connected to the grid in 1941 on Grandpa's Knob in Castleton, Vermont. Palmer Cosslett Putnam designed it and the S. Morgan Smith Company built it. Rated at 1.25 MW, it sat on a 37 metre steel lattice tower, and one of its blades broke off on 26 March 1945. In Denmark, Johannes Juul's 200 kW Gedser turbine of 1957 set the three blade layout that most turbines still use.

The Smith-Putnam wind turbine on its steel lattice tower at Grandpa's Knob, Vermont, around 1941. Photo: United States Government via Wikimedia Commons (public domain)

As turbines grew, tubular steel towers replaced lattice ones, and the welding process that made them practical was already decades old. The first submerged arc welding patent was taken out in 1935 by Lloyd Jones, Harry Kennedy and Maynard Rothermund. The arc burns under a blanket of granular flux, which hides it and lets it lay down a lot of metal without spatter. Systems can feed two to five wires at once, and multi arc setups have run at up to 5000 A, which is why the process suits the thick plate in towers.

A submerged arc welding head working under a heap of granular flux on thick steel plate for a wind energy structure, 2012. Photo: Martinhannes / Wikimedia Commons (CC BY-SA 4.0)

A tower factory follows a fixed sequence. Plates are cut and bevelled, rolled into cylindrical or conical "cans", and closed with a longitudinal seam. Flanges are fitted. Rollers then turn the cans under a fixed submerged arc head on a column and boom while the circumferential seams that join them are welded. Last comes the door frame. Most of these steps were mechanised long ago, but the door frame stayed manual: fabricators often cut the opening with a template and weld the heavy frame with a handheld sub arc gun.

A submerged arc welded joint in thick plate, with root, fill and cap passes laid from both sides. Photo: Martinhannes / Wikimedia Commons (CC BY-SA 4.0)

Monopile plants and robot cells today

Offshore wind has pushed the same process to a far larger scale. On 26 August 2026 JFE Engineering finished Japan's first domestically made monopile at its Kasaoka factory in Okayama Prefecture, which opened in March 2024. The piles for the Oga, Katagami and Akita project measure about 11 metres across and 80 metres long. JFE uses heavy J-TerraPlate steel from JFE Steel to cut the amount of welding. In Germany, EEW said in September 2026 that its Rostock plant will make monopiles up to 12 metres wide and 3,000 tonnes from 2028.

Rolled steel cans, each about 3 metres long, before submerged arc welding into parts for offshore wind tripods, 2012. Photo: Martinhannes / Wikimedia Commons (CC BY-SA 4.0)

Robots are arriving first where welding is still slow and irregular. Lincoln Electric has called the door frame the biggest bottleneck in tower construction, because the tower wall is curved, the frames are heavy and accuracy depends on the welder. Its concept puts a robot on the end of a manipulator, and the robot scans the part before it welds. PEMA, a Finnish maker of welding lines, sells a robotised door frame cutting and welding station that uses its WeldControl scanning software, which PEMA says makes programming fast. It also sells flange fitting stations for the same lines.

The heavy lift vessel Les Alizés loading XXL monopiles at the Port of Leith for the Inch Cape wind farm, March 2026. Photo: Drnoble / Wikimedia Commons (CC BY-SA 4.0)

ABB does not sell complete tower lines, and we found no public ABB tower welding project. Its standard arc welding hardware would still fit these cells. A large arm such as the IRB 6700 can carry a heavy torch or a grinder on a linear track, and ABB positioners turn parts so the robot can weld in the flat position. With MultiMove one controller drives the robot and the positioner as a single system, and external axes such as tracks are programmed the same way. Putting ABB robots on a tower line would be a choice made by an integrator.

An ABB arc welding robot with a positioner that turns heavy parts. Photo: Ana 2016 / Wikimedia Commons (CC BY-SA 4.0)

What comes next for tower and monopile welding

Monopiles are heading for 15 metre diameters, which EEW says it may need after 2030. Walls get thicker as diameters grow, so each circumferential seam takes more passes, and a defect found late can cost days of rework. Expect more seam tracking and adaptive fill, with every pass inspected automatically. Programs for welding cells this size are usually built and checked first in RobotStudio, because a collision inside a 12 metre can is an expensive thing to discover on the real part.

Looking down the inside of a finished tower section at Enercon Windtower Production in Malmö, 2014. Photo: Johan Wessman / News Oresund via Wikimedia Commons (CC BY 2.0)

Safety is the other driver. In early October 2026 Wind Power Monthly and Recharge, citing local media, reported that a worker died at CS Wind's tower factory at the port of Aveiro in Portugal. The short reports I could read gave no cause, so this post does not guess at one. In general, tower and monopile work puts people inside large steel tubes and under cranes for hours. Every weld, grind or inspection that a robot or a remote station takes over is time a person does not spend in there.

An ABB IRB 6700 grinding a steel part in Teqram's EasyGrinder cell at Ancofer. Photo: ABB

Skills and cost will set the pace. EEW's Rostock upgrade alone runs to tens of millions of euros, the order book swings with offshore auctions, and the welders who set up these machines take years to train. Smaller jobs on onshore towers, such as brackets and door frames, suit cobots like the GoFa CRB 15000 with ABB's cobot arc welding package, which a welder teaches by moving the arm by hand. For the big circumferential seams, the submerged arc head on its boom looks set to stay, with robots taking over the awkward work around it.

ABB's GoFa Cobot Arc Welding Package on a welding table, with the torch guided by hand. Photo: ABB

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