Underwater welding is performed while the welder is submerged, often at elevated barometric pressures. This introduces a variety of challenges that require specialized skills and training that are taught at CDA Technical Institute (formerly Commercial Diving Academy). Because of the adverse conditions and inherent dangers associated with underwater welding (also known as wet welding) divers must be trained to an exceptionally rigorous standard with highly specialized instruction.
Welding underwater can be acheived by two methods: wet welding & dry welding. Wet welding entails the diver to perform the weld directly in the water. It involves using a specially designed welding rod, and employs a similar process used in ordinary welding.
Here are advantages to wet welding:
Cheap and fast
high tensile strength
ease of access to weld spot
Dry Welding / Hyperbaric Welding
Another method of welding underwater is hyperbaric welding or dry welding. Hyperbaric welding is the process by which a chamber is sealed around the structure that is to be welded. It is then filled with a gas (typically mixture of helium and oxygen, or argon), which then forces the water outside of the hyperbaric sphere.
This allows for a dry environment in which to perform the weld. Here are some advantages to dry welding: