Submerged Arc Welder

Submerged arc welding (SAW) is the workhorse for long seams in thick plate. The arc burns entirely beneath a blanket of granular flux: no visible arc light, virtually no spatter, very low fume, deep penetration and a smooth bead profile. It is the standard choice wherever weld quality and deposition rate both matter — pressure vessels, boilers, pipe, wind-tower sections and bridge steel. The Icyrobot ZD7 range covers 630 A to 2000 A.

Why SAW is both fast and clean

The flux layer isolates the arc from air completely, which pays off three ways:

• Very high thermal efficiency — almost all arc energy melts base metal and wire; penetration beyond 20 mm is routine, and thick plate often needs a much smaller prep or none at all;
• No spatter, no arc glare — filler utilisation approaches 100%, the working environment improves dramatically, and no screens or hoods are needed for bystanders;
• Stable bead shape — the molten slag mechanically supports the pool, giving consistent reinforcement and width with little or no post-grinding.

ZD7 current classes and typical duty

Ranges are for single-wire welding; tandem or twin-wire and strip cladding raise capability substantially.

DC versus AC power sources

DC SAW gives a stable arc, deep penetration and high melt rate, and suits most carbon and low-alloy steels. AC SAW resists arc blow at very high current and avoids mutual interference in tandem setups — hence the common "DC lead wire + AC trail wire" combination. The ZD7 range is DC and covers the great majority of conventional thick-plate work.

What a complete SAW station includes

• Welding power source (this section) and wire feeder;
• Welding column/gantry or turning rolls to create relative motion;
• Flux recovery unit to recycle unfused flux — a direct cut in consumable cost;
• Seam tracking to hold long straight seams on the joint centreline;
• Flux baking oven — damp flux is the number one source of hydrogen porosity.

Common defects and remedies

Frequently asked questions

Is SAW limited to the flat position?

Effectively yes. Flux is held on the pool by gravity, so horizontal, vertical and overhead positions cannot maintain the blanket. SAW is used flat or in the fillet (boat) position, with a positioner to bring other joints to flat.

How many times can flux be reused?

Unfused flux can be screened and recycled, typically 3–5 cycles before topping up with fresh flux and re-checking particle size and moisture. Beyond that, porosity and poor slag release appear.

How many wire feeders can one source drive?

Normally one wire per source. Tandem or twin-wire needs a separate source and feeder per wire, synchronised for wire spacing and phase.

For thick-plate automatic welding schemes and matching equipment, contact the Icyrobot technical team.