1.5 SAW — Submerged Arc Welding
Key Takeaways
- SAW submerges the arc under granular flux — no visible arc, no spatter, no UV radiation
- Limited to flat and horizontal positions because the flux relies on gravity
- Highest deposition rate of any single-arc process: 25–100+ lbs/hr
- Uses constant voltage (CV) power source with bare solid or cored wire electrode
- Three flux types: fused (non-hygroscopic), bonded (adds alloying, hygroscopic), agglomerated
- Ideal for long straight or circular welds: plate girders, pipe seams, pressure vessels, wind towers
1.5 SAW — Submerged Arc Welding
Submerged Arc Welding (SAW) is a high-production, fully mechanized or automatic process where the arc is completely hidden (submerged) beneath a blanket of granular flux. It produces the highest deposition rates of any single-arc welding process.
Process Fundamentals
- A bare solid or cored wire electrode is fed into the joint
- Granular flux is deposited ahead of or concurrent with the arc, completely covering it
- The arc melts the electrode, base metal, and some of the flux to form the weld pool
- Because the arc is submerged in flux, there is no visible arc, no spatter, and no UV radiation
- Unfused flux is recovered and recycled
SAW Equipment
| Component | Function |
|---|---|
| Power source | Constant voltage (CV) for most applications; CC for some |
| Wire feeder | Feeds electrode wire from coils or drums |
| Flux hopper | Stores and deposits granular flux onto the joint |
| Flux recovery system | Vacuums and recycles unfused flux |
| Travel mechanism | Tractor, side beam, gantry, or other automated carriage |
SAW Wire and Flux Classification (AWS A5.17)
Wire Example: EL12 — "E" = electrode, "L" = low manganese, "12" = 0.12% nominal carbon content
Flux-Wire Combination Example: F7A2-EL12
| Character | Meaning |
|---|---|
| F | Flux |
| 7 | Minimum tensile strength (70 ksi) |
| A | As-welded (no PWHT) |
| 2 | Charpy impact ≥ 20 ft-lb at -20°F |
| EL12 | Electrode classification |
Flux Types
| Type | Characteristics |
|---|---|
| Fused flux | Manufactured by melting raw materials, then crushing; homogeneous, non-hygroscopic, easily recycled |
| Bonded flux | Raw materials bonded with a binder and baked; can add deoxidizers and alloying elements; hygroscopic |
| Agglomerated flux | Similar to bonded but manufactured differently; can add alloys; moderate moisture pickup |
Key Operating Parameters
| Parameter | Typical Range | Effect |
|---|---|---|
| Current | 300–2,000+ A | Controls penetration and deposition rate |
| Voltage | 28–40 V | Controls bead width and flux consumption |
| Travel speed | 10–120+ IPM | Controls bead width, penetration, and heat input |
| Electrode diameter | 3/32" – 1/4" (2.4–6.4 mm) | Affects current-carrying capacity |
| Stickout (CTWD) | 1"–1.5" typical | Affects preheating of electrode and deposition |
Applications
SAW is ideal for high-volume, long, straight or circular welds in flat or horizontal position:
- Plate girders and beam fabrication
- Pipe longitudinal and spiral seams
- Pressure vessel shell and head welds
- Wind tower fabrication
- Ship hull panels
- Bridge girders
- Storage tanks
Advantages and Limitations
| Advantages | Limitations |
|---|---|
| Highest deposition rate (25–100+ lbs/hr) | Flat and horizontal position only |
| No visible arc — reduced UV and fume exposure | Limited to straight or circular joints |
| No spatter | Flux handling and recovery adds complexity |
| Deep penetration (up to 1" in single pass) | Cannot see the arc — difficult to monitor |
| Excellent bead appearance | Bonded/agglomerated flux can absorb moisture |
| High-quality, consistent welds | Higher initial equipment cost |
| Recyclable unfused flux | Primarily for ferrous metals |
For the Exam: SAW is limited to flat and horizontal positions only because the granular flux relies on gravity to stay in place. It has the highest deposition rate of any single-arc process but cannot be used for vertical or overhead welding.
Why is SAW limited to flat and horizontal welding positions?
What is the approximate deposition rate range for SAW?
In the SAW flux-wire classification F7A2-EL12, what does "A" indicate?