What Is SAW Welding?
Quick Answer: SAW (Submerged Arc Welding) is a high-productivity automatic process where the arc burns beneath a blanket of granular flux. The flux completely covers the arc, eliminating spatter and UV radiation while producing deep-penetration welds at deposition rates up to 45 kg/h. SAW is the primary process for manufacturing longitudinal and spiral-welded line pipe and for welding thick-wall pressure vessels.
How SAW Works
A bare solid or cored wire electrode is fed continuously into the joint while granular flux is deposited ahead of the arc from a hopper. The arc melts the wire, base metal, and a portion of the flux. The molten flux forms a protective slag layer; unfused flux is recovered and recycled. Because the arc is submerged, there is no visible arc flash, minimal fume, and zero spatter.
| Parameter | Typical Range |
|---|---|
| AWS designation | SAW (per AWS A3.0) |
| Wire diameter | 2.0 to 6.0 mm (5/64” to 1/4”) |
| Current | 300 to 2,000 A |
| Voltage | 25 to 45 V |
| Travel speed | 200 to 2,000 mm/min |
| Deposition rate | 5 to 45 kg/h (single and tandem wire) |
| Polarity | DCEP or AC |
| Flux types | Fused, bonded, agglomerated (per AWS A5.17/A5.23) |
| Positions | Flat and horizontal only |
| Governing codes | ASME Section IX, AWS D1.1, API 5L, API 1104 |
SAW Applications in Piping
| Application | Details |
|---|---|
| LSAW pipe (longitudinal SAW) | UOE or JCOE forming + double SAW seam; API 5L X42 to X80 |
| SSAW/HSAW pipe (spiral SAW) | Helical seam welding for water, structural piling |
| Pressure vessels | Longitudinal and circumferential seams per ASME Section VIII |
| Storage tanks | Shell courses per API 650 |
| Pipe pup pieces | Girth welds on large-diameter pipe (NPS 24+) rotated on rollers |
| Weld overlay/cladding | Corrosion-resistant weld overlay with strip electrode variant |
SAW Flux Types
| Flux Type | Manufacturing | Characteristics |
|---|---|---|
| Fused | Raw materials melted in furnace, cooled, crushed | Glassy, non-hygroscopic, easy to recycle |
| Bonded | Ingredients bonded with silicate binder, baked | Can add alloy elements, lower current capacity |
| Agglomerated | Similar to bonded but sintered at higher temperature | Balance of bonded flexibility and fused stability |
Limitations
SAW is restricted to flat and horizontal positions because the granular flux relies on gravity. This means it cannot weld fixed-position field joints. Field girth welds on pipelines are welded by SMAW, GMAW, or FCAW, while SAW handles the pipe mill seam and shop-fabricated joints.
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