Very high deposition rate, deep penetration, and consistent weld quality over long seams, with almost no spatter to clean off. The flux blanket blocks arc radiation and captures most of the fume, so the working environment is markedly better than open-arc processes. On heavy plate it deposits several times the metal per hour of manual welding.

Position, above all: the granular flux must sit on the joint, restricting the process to the flat position and horizontal fillets. It also needs consistent fit-up and usually backing, suits long runs rather than short intricate joints, and gives the operator no view of the arc, so faults are found by tracking, monitoring and post-weld inspection rather than by eye.

Typically from around 5 mm upwards, with no real upper limit given multiple passes - pressure vessel shells, tank walls and heavy structural sections of 100 mm and beyond are routinely welded this way. Below about 5 mm the heat input and penetration become difficult to control and open-arc processes are usually a better fit.

Both are used. DC electrode positive gives the deepest penetration and is common for single-wire work. AC reduces arc blow, which becomes a serious problem at high current and in multi-wire configurations where adjacent arcs interact magnetically, so tandem and multi-wire systems frequently run a DC lead wire with AC trail wires.

Two or more wires feeding into the same or closely following pools, each with its own power source and parameters. Tandem arrangements typically use a DC lead arc for penetration and an AC trail arc to shape and fill, raising travel speed and deposition well beyond a single wire. It demands tighter control of arc interaction and fit-up.

No. The molten flux and the gas it generates as it decomposes shield the pool completely, which is why no external gas supply appears in the equipment list. The flux additionally shapes the bead, refines the weld metal chemically and can carry alloying additions into the deposit.

A submerged arc variant using a wide strip electrode instead of round wire to deposit corrosion-resistant overlay - typically stainless or nickel alloy - onto a carbon steel base. It covers a much greater area per pass with low dilution, and is standard for the internal surfaces of pressure vessels and reactors in process plant.