Underwater welding is suitable for offshore under water welding applications. It is of two types: dry and wet. In dry underwater welding, the weld-surrounding is made dry and welding is done as if done in air. In wet underwater welding, welding is done in water- environment. The wet underwater welding is faced with several problems and one main problem is that it is difficult to maintain the arc-stability. The paper reports a study of means to improve the arc- stability in the wet underwater welding. It is found that an organic coating over the normal electrode improves the arc-stability. Effect of environment- salinity and pH value are also studied. It is found that water salinity and artificially created basic solution(pH> 7)near the weld area improves the arc-stability and hence the weld- quality ＿ Arc-stability improves significantly if a negative electrode-tilt is employed. The Wet underwater welding can also be done on land, intentionally, for minimizing-distortion, for hard facing and for corrosion-prevention.
Underwater welding is suitable and widely used for off-shore under-water construction and repair applications. The applications include: emergency repair in sea, salvage wrecks, welding of ship" s hull, construction and repair of offshore oil drilling platforms and underwater pipelines, attaching sacrificial anode to marine- structures etc. A significant increase in underwater welding started around 1960 primarily to meet the needs of off-shore oil drilling industries[1,2]. For dry underwater welding, the weld place is surrounded in a dry chamber and welding is done as if done in air. It is the wet underwater welding which literally is true under-water welding in water environment. Dry and wet underwater welding both are essentially arc-welding, in general.
However, quality of welds produced by wet underwater welding are comparatively poor due to quench-hardening, porosity and hydrogen induced cracking.
