Hyperbaric welding is done below the ocean’s surface or in any large body of water. This type of welding is done mainly on offshore oil platforms or used to repair ships and pipelines that are located under the sea. In most cases, these repairs are done using steel. There are two forms of underwater welding, they are known as dry welding and wet welding and they all fall under the term hyperbaric welding.
Both forms take place underwater (as you probably guessed). In the case of dry welding, the process is carried out in a special chamber which uses pressure to create a dry environment. The dry mode is better managed underwater. This method is only used when the welds needs to possess a certain level of strength. Currently, research is been carried out to see if underwater dry welding can take place at depths of 1,000 meters.
The pressure for dry welding is created by filling the chamber with a mixture of gasses, that creates a seal for the item that is about to be welded. To increase the strength of a weld arc TIG welding is used.
Wet welding comes with a number of risks. There is a level of uncertainty when this process is used to seal or join objects underwater. Because the underwater environment is so unpredictable the strength of the seal made by the weld is hard to determine. Plus, defects are difficult to locate.
There are several submerged welding several methods that can be used. These are friction welding, flex core arc welding and shielded metal arc welding. A waterproof electrode is used for the weld process, because metal cracks when it comes in contact with hydrogen (hydrogen is a main component of water). Low carbon steel is also used to carry out these welds.
Hyperbaric welding poses several risks, one which is due to the environment. Because the equipment uses electricity there is the possibility of electrocution in a wet environment. This is likely to happen if the equipment in use was not designed to operate in a marine setting. Any hyperbaric welding equipment you use should be thoroughly tested in and made for watery environments. Proper insulation and an adjustable welding current is necessary in any underwater setup.
Another factor to consider is decompression sickness. Welders who are working underwater for extended periods of time will require pressurized oxygen for breathing. Once they emerge from the water returing to an environment where the oxygen is not pressurized can cause problems.
Hydrogen and oxygen are two explosive gases. While working underwater they may build in pockets creating a hazard. Divers have complained that when amalgam is used they experience a metallic taste. Musculoskeletal issues and slowed cognitive processing are also problems that may develop when divers remain underwater for extended periods of time.
Welders need to be aware of the safe practices to ensure there safety while they are underwater. Hyperbaric welding is dangerous and requires lots of training, that is why underwater welding pay is so high.