Key Takeaways
- Submerged arc welding (SAW) produces the arc entirely beneath a blanket of granular flux — making it invisible during operation and producing no spatter, arc flash, or UV exposure in the surrounding area.
- SAW is an automated or semi-automatic process almost exclusively used for flat or horizontal welds on thick material in production environments — it’s not a manual, positional welding process.
- Wire diameter for SAW typically runs 3/32″ to 1/4″ depending on application, with smaller wire used for precision multi-pass work and larger wire for high-deposition production passes.
- In SAW, amperage primarily controls penetration depth — higher amperage drives the arc deeper into the base metal, while voltage controls bead width and travel speed controls bead profile and heat input.
- Sub arc welder salaries run $18–$38 per hour depending on industry, location, and experience, with machine operator roles in heavy industry averaging around $70,000 annually.
What Is Sub Arc Welding?
Submerged arc welding (SAW) is an arc welding process where the arc forms between a continuously fed wire electrode and the base metal, completely submerged beneath a layer of granular flux that covers the joint ahead of the weld. The arc is invisible from the outside — unlike MIG, TIG, or stick welding, there’s no visible arc flash, spatter, or fume plume during operation. The flux blanket simultaneously shields the molten weld pool from atmospheric contamination, stabilizes the arc, and refines the weld metal chemistry as it melts and solidifies.
The result is one of the highest deposition rate welding processes available, capable of depositing substantially more metal per hour than manual arc processes — which is exactly why it’s the standard choice for high-volume production of thick-section structural components.
How Sub Arc Welding Works
The process uses a mechanized or automated travel system to move the welding head (or the workpiece) at a controlled speed while the wire electrode feeds continuously into the joint. Granular flux is deposited ahead of the travel direction through a hopper, completely covering the joint and the arc zone. Current passes through the wire, the arc melts both the wire and the base metal, and the flux above melts to form a protective slag layer over the cooling weld bead — similar in function to stick welding’s flux coating, but applied externally and in far greater volume.
After welding, the solidified slag layer is chipped and the unmelted flux is recovered and recycled for reuse — one of the process’s practical economic advantages on high-volume production runs.
What Does Amperage Do During Sub Arc Welding?
In SAW, each of the three primary settings controls a distinct aspect of the weld geometry:
Amperage controls penetration. Higher amperage drives the arc harder into the base metal, increasing penetration depth into the workpiece. This is the most direct variable for controlling how deeply the weld fuses into thick material — insufficient amperage for the material thickness produces incomplete fusion, while excessive amperage can cause burn-through or cracking on thinner sections.
Voltage controls bead width and arc length. Higher voltage produces a wider, flatter bead with a longer arc; lower voltage concentrates the arc and produces a narrower, more convex bead. Voltage and amperage interact — a change in one typically requires adjustment of the other to maintain a balanced bead profile.
Travel speed controls bead profile and heat input. Slower travel speed increases the amount of weld metal deposited per inch and increases heat input per unit length, producing a wider, taller bead with more dilution of the base metal. Faster travel speed deposits less metal and reduces heat input, producing a narrower bead with a different cross-sectional profile.
What Size Wire for Sub Arc Welding?
Wire diameter selection for SAW depends on the application, current level, and whether the focus is single-pass productivity or multi-pass precision:
Small diameter wire (3/32″ to 1/8″ / 2.4mm to 3.2mm) — used for multi-pass welds requiring more precise bead placement and heat control, or for applications where positional considerations (horizontal position rather than flat) demand better puddle control than large diameter wire allows.
Medium diameter wire (5/32″ to 3/16″ / 4.0mm to 4.8mm) — the most common range for general production work on structural components, pressure vessels, and pipe fabrication, balancing deposition rate with controllability.
Large diameter wire (7/32″ to 1/4″ / 5.6mm to 6.4mm) — used for maximum deposition rate applications on very thick material where single-pass or minimum-pass welding is the production priority. Requires correspondingly high amperage and is typically used on heavy structural fabrication.
Wire diameter directly determines the usable amperage range — small wire at high amperage burns back faster than it can feed, while large wire at low amperage produces inconsistent fusion and poor arc stability.
What Are the Disadvantages of Sub Arc Welding?
Limited to Flat and Horizontal Positions
The granular flux that makes SAW possible also makes it position-dependent — the flux must stay in place over the arc zone, which requires gravity to hold it there. This limits SAW almost entirely to flat (1G) and horizontal (2G) positions; vertical or overhead welding isn’t practical with standard SAW equipment.
High Equipment Cost and Complexity
SAW requires a mechanized travel system, wire feeder, flux hopper and recovery system, and often a positioning fixture to orient the workpiece in the flat position — a significantly higher capital investment than setting up a manual MIG or stick welding station.
Limited to Thicker Material
SAW’s high heat input and deposition rate are advantages on thick material but disadvantages on thin gauge — burn-through and distortion make SAW impractical on material thinner than approximately 5mm without significant parameter adjustment or specialized techniques.
Slag Removal Between Passes
On multi-pass welds, the solidified slag must be completely removed between passes — incomplete slag removal causes slag inclusions that compromise weld integrity, adding a quality control step that manual MIG welding doesn’t require.
No Arc Visibility
The invisible arc means the operator can’t visually monitor the weld pool during welding — quality assurance depends entirely on parameter control and post-weld inspection rather than real-time visual monitoring.
What Are the 4 Types of Arc Welding Process?
The four most commonly referenced arc welding processes cover the majority of hands-on fabrication work across the industry:
SMAW (Shielded Metal Arc Welding / Stick Welding) — the most portable arc process, using a flux-coated consumable electrode that self-shields.
GMAW (Gas Metal Arc Welding / MIG Welding) — continuous solid wire feed with external shielding gas, the fastest manual arc process for most shop work.
GTAW (Gas Tungsten Arc Welding / TIG Welding) — non-consumable tungsten electrode with separate filler rod and inert gas, producing the most precise and cleanest welds.
FCAW (Flux-Cored Arc Welding) — continuous tubular flux-filled wire, with self-shielded variants needing no external gas for outdoor and high-deposition work.
SAW is typically listed fifth in the arc welding category — included when sources expand to a five-process framework covering AWS certification categories. Unlike the four processes above, SAW is almost always automated rather than manual, which is why it appears in a separate tier from the four hands-on processes beginners encounter first.
How Much Does a Sub Arc Welder Make?
Submerged arc welder pay runs $18–$38 per hour depending on industry, location, and experience, with machine operator roles averaging around $70,000 annually and specialized positions in heavy manufacturing and shipyard work reaching $28–$38 per hour. The role is closer to an industrial machine operator with welding knowledge than a manual welder — SAW operators are responsible for setting up equipment, programming parameters, monitoring automated runs, and interpreting quality results rather than manually guiding a torch.
Higher-end positions in shipyard fabrication, pressure vessel manufacturing, and heavy structural production tend toward the top of this range, while entry-level production roles start closer to the bottom. The specialized nature of SAW equipment means operators with specific machine experience and AWS certification for the process command a premium over general welders cross-training into the role.
Where Sub Arc Welding Is Used
SAW’s combination of high deposition rate, deep penetration, and clean, consistent quality without UV exposure risk makes it the standard process for several specific high-volume applications:
Structural steel fabrication — wide flange beam and column welding, particularly long continuous fillet welds on beam flanges.
Pressure vessel and tank manufacturing — longitudinal and circumferential seam welds on cylindrical vessels where flat or horizontal position can be maintained by rotating the workpiece.
Pipe manufacturing — spiral and longitudinal seam welding on large diameter line pipe, often combined with outside-then-inside pass sequences for full penetration.
Shipbuilding — deck plate and structural seam welding where flat position work can be organized efficiently across large panel sections.
How to Set Up SAW Parameters: Step-by-Step
- Select wire diameter for your material thickness and current range. Thicker material points toward larger diameter wire; multi-pass precision work points toward smaller.
- Set amperage to achieve the penetration depth required by the joint design. Start at the low end of the appropriate range for your wire diameter and adjust up if penetration on the test weld is insufficient.
- Adjust voltage to produce the correct bead width. A flat-profile bead with gradual toes indicates good voltage balance; convex bead suggests higher voltage may be needed.
- Set travel speed to control bead profile and heat input. Run a test weld, measure the bead profile, and adjust speed to hit the reinforcement and width called for in the WPS.
- Check flux coverage depth. Too shallow and the arc becomes visible with associated UV and spatter; too deep traps gas and causes porosity.
Common Mistakes With Sub Arc Welding
- Assuming high deposition rate automatically equals efficiency — productivity from SAW only materializes on joints that can be consistently held in the flat or horizontal position; forced-position workarounds eliminate the advantage.
- Skipping flux moisture control — granular SAW flux absorbs moisture like low-hydrogen stick electrodes, and damp flux causes porosity and hydrogen-related cracking.
- Inconsistent flux coverage depth — too little or too much flux both compromise weld quality in ways that aren’t visible until after welding and slag removal.
- Ignoring slag removal quality between passes — slag inclusions from incomplete interpass cleaning are among the most common SAW quality failures in multi-pass work.
- Treating amperage and voltage as independent settings — they interact directly; adjusting one without checking the other’s effect on bead profile produces inconsistent results.
Wrapping Up
Submerged arc welding is one of the most efficient, highest-quality production welding processes available — but its advantages only materialize in the specific conditions it’s designed for: thick material, flat or horizontal position, and high-volume automated or semi-automatic production work. Outside those conditions, its position limitations and equipment complexity work against it rather than for it. Understanding what SAW is specifically optimized to do is what separates choosing it correctly from trying to apply it where a manual process would serve better.
Frequently Asked Questions
What are the disadvantages of sub arc welding?
The main limitations are positional restriction to flat and horizontal only, high equipment cost and complexity compared to manual processes, impracticality on thin material due to high heat input, the requirement for slag removal between passes, and the inability to visually monitor the weld pool during welding.
How much does a sub arc welder make?
Sub arc welding positions typically pay $18–$38 per hour depending on industry and experience, with specialized machine operator roles in heavy manufacturing and shipyard work averaging around $70,000 annually.
What are the 4 types of arc welding process?
The four most commonly referenced arc welding processes are SMAW (stick), GMAW (MIG), GTAW (TIG), and FCAW (flux-core) — with SAW typically added as a fifth process when sources expand to cover AWS certification categories.
What size wire for sub arc welding?
Wire diameter for SAW typically runs 3/32″ to 1/4″ (2.4mm to 6.4mm), with smaller diameter wire used for multi-pass precision work and larger diameter wire used for maximum deposition rate on thick material.
What does amperage do during sub arc welding?
Amperage primarily controls penetration depth — higher amperage drives the arc deeper into the base metal. Voltage controls bead width and arc length, while travel speed controls bead profile and total heat input per unit length.