Submerged Arc Welding (SAW)
The invisible arc—highest deposition rate for thick plates and large series
AI generated In submerged arc welding, the arc burns under a thick layer of flux—invisible and completely covered. It's the process with the highest deposition rate: the standard for thick plates, vessels, shipbuilding, and wind towers.
Submerged arc welding (SAW, number 121 according to DIN EN ISO 4063) is the powerhouse among welding processes. An endless wire electrode is fed continuously, and the arc burns between the wire and the workpiece—but you can't see it. Over the weld spot lies a thick layer of flux that completely covers the arc.
The flux has two jobs: it melts in the arc and forms a slag that covers the weld and protects the pool from the atmosphere—so SAW doesn't need a separate shielding gas. But the flux can do more: depending on the type, it alloys the weld by releasing alloying elements to the molten pool. Wire and flux are chosen as a pair—the wire brings the base material, the flux the fine-tuning of alloy and slag control.
This gives the big advantages:
• Highest deposition rate: No other arc process deposits as much material per hour. Thin welds on thick plate are no problem.
• Deep penetration: The concentrated heat melts deep—often one pass is enough where MAG would need several.
• No visible arc, little fume: The arc burns under the flux—that's easier on eyes and environment.
• Clean, uniform welds: mechanized and reproducible—ideal for long seams.
For even more performance, you couple several wire electrodes in a row (multi-wire or tandem SAW)—this creates very wide or very deep welds in one pass.
The drawbacks: SAW works practically only in flat position (the flux would otherwise slide off), the equipment is heavy and stationary, and the solidified slag must be removed. For thin sheets below about 5 mm, it's too coarse.
The domain of SAW is thick sections and long seams: pressure vessels, tanks, shipbuilding, wind tower sections, bridges, and boilers. Wherever you need meter after meter of weld at maximum deposition rate, submerged arc welding rules.