Problem Areas In UnderWater Welding

Underwater Welding in Wet - Under water welding has made it possible to repair underwater heavy structures that cannot be transported to land, to weld in air. This technique can be applied for repair works on heavy ship hulls, oil and gas pipeline structures. Efforts have been made to improve the quality of wet welds (welds made in wet conditions) but there are some problem areas that highly influence their quality. Following are the downsides of underwater wet welding that ought to be improved in order to made high quality welds in future.

1.Welder’s Visibility
The first and foremost requirement of wet welding, is welder’s visibility under water. The welder must be able to see and manipulate the welds inside the water. For recent years efforts have been made to improve the equipment that can provide welders, a clear view of arc.

2.Heat Transfer
During wet welding process, arc and base metal zone is surrounded by water that gives rise to a quenching effect due to high temperature gradient. As a result ductility of weldment gets reduced along with failure of other mechanical properties. 

The weld zone is surrounded by high amount of water vapors due to which hydrogen and oxygen content is entrapped into the weldment. This entrapment gives rise to devastating porosity and hydrogen induced cracking. In order to prevent such consequences, arc zone should be kept free from water vapors under wet conditions.

Apart from weld quality, under water (wet) welding requires more safety and risk assessment as compared to the welds made in air. For this water proof electrode holders are being used and also an emergency switch called knife switch is operated on the land surface under the instructions of welder diving in water. Welding cables, electrodes and connections must be made water proof by proper insulation, to avoid any contact with water. Underwater welding is further divided into sub categories; wet welding and dry welding under water