How is it possible to weld under water???

Question

I.e on oil rigs and things....How does the arc stay lit when its submerged in sea water????

Answer 1

Yes.  Electricity is used, not a flame.

Underwater welding (underwater arc welding) is a process used to join to pieces of metal together with a type of filler metal. Under water welding is very similar to topside welding with the exception of a few safety precautions that are instrumental for a safe work environment. In order to become a underwater welder you need to attend a commercial diving school (underwater welding tech. school).  Normally, these schools last 2 to 6 months long however there is one in Santa Barbra that has a 2 year program. The 2 to 6 month programs in general require at least 25 hours a week .

In dry underwater welding, the weld is performed at the prevailing pressure in a chamber filled with a gas mixture sealed around the structure being welded. For this process, gas tungsten arc welding is often used, and the resulting welds are of high integrity.

For the structures being welded by wet underwater welding, inspection following welding may be more difficult than for welds deposited in air. Assuring the integrity of such underwater welds may be more difficult, and there is a risk that defects may remain undetected.

In wet underwater welding, a variation of shielded metal arc welding is commonly used, employing a waterproof electrode. Other processes that are used include flux-cored arc welding and friction welding.  In each of these cases, the welding power supply is connected to the welding equipment through cables and hoses. The process is generally limited to low carbon equivalent steels, especially at greater depths, because of hydrogen-caused cracking.

Answer 2

I'm aware of a system of welding which involves effectively 'drilling' a stud into the metal, and the heat from the friction created vapourises the water around the weld!