Madatov in 1969 studied the weld shapes obtained in underwater welds using 5 mm EPS 52 (iron powder) electrodes and represented these in terms of weld penetration shape factor or simply “shape-factor” defined as the ratio between the weld width and depth of penetration. He reported that as welding current increased, weld reinforcement remained constant but the width of the weld increased and the penetration decreased with the result that the “shape factor” increased from 3.50 at about 200 amp to 5.00 at about 300 amps. Decrease in penetration was explained by stating that the travel speed increased on the mechanised feeding arrangement used. He also found, using a GMA process with 1.2 mm wire at 34 to 43 volts that the penetration shape factor varied between 2.5 to 5.00.

Increase in salinity or hydrostatic pressure reduced the shape factor. As the angle of torch nozzle changed from a leading to a trailing angle, the bead became narrower and taller with decreased penetration. A larger lead angle was supposed to increase post heating to the weld puddle and increase the metal flow back into the sides of the weld crater.

Silva in 1971 also investigated under water shielded metal are welding and reported shape factor of 4.2 to 5.4. He claimed that sufficient energy was required to bring the heat - affected-zone to approximately the size as in air. He found that the penetration did not decrease under water as claimed by other investigators. Rutile electrode E(6013) gave a semicircular penetration profile whereas with iron powder electrodes (E-7024 and E-6027), penetration was deep in the centre and tapered off rapidly towards the edges of the bead. Increased in penetration might be due to long barrel in iron powder electrodes.

Masumoto et al. in 1971 using a 4 mm coated iron powder electrode obtained underwater welds at 150 to 180 amps. The penetration shape factors were found to be between 5 to 7. Gas metal arc welds at 120 to 210 amps gave shape factor between 3 to 5.5.

Billy in 1971 investigated GMA welding and found that at a voltage of 36 to 42 volts, the shape factors varied from 2.1 to 2.9 reflecting quite good penetration that was obtained.

Hasui et al. in 1972 developed a plasma arc welding process that gave excellent welds. For welds without shielding liquid, the ratio was 1.7 to 4.2 and with shielding the ratio was between 1.8 to 2.3. The plasma welding appears to give better weld shape than either shielded metal arc or gas metal arc welding processes.