Underwater welding is one of the world’s most challenging professions.

Aspiring welders require several years of training — including diving certifications — before they are allowed to work for extended periods underwater.

However, hyperbaric welding, as underwater welding is also known, is often used in the maintenance of ships or working on offshore pipelines and is thus an extremely crucial occupation. 

So how does it work? And what role do gases play? Let’s take a closer look. 

How does underwater welding work? 

There are two types of hyperbaric welding — wet welding and dry welding. 

In dry welding, the structure that is to be worked on is sealed by what is known as a hyperbaric chamber. All water is first pumped out of this chamber. The air inside is, meanwhile, maintained at a higher pressure than the water outside to ensure that the welder doesn’t get sick while working.

In some cases, welders may even create larger “habitats” for dry welding, which can accommodate two to three divers at a time. These habitats are similarly pumped with gases to maintain a breathable atmosphere for the welders. 

Wet welding, on the other hand, is mostly used in emergencies or when there is no access to a hyperbaric chamber. In this case, air bubbles are released to surround an electric arc to protect the weld and reduce the electric conductivity of water.

Wet welding is very challenging as the bubbles make it harder for welders to see what they’re working on. The welds created also tend to cool rapidly, increasing the possibility of defects, while the pools are at an increased risk of contamination. 

Welders must also protect themselves from shocks by wearing special diving suits and using equipment that is more heavily insulated than the average welding torch.

The Role of Gases in Underwater Welding

Gases play a crucial role in both wet and dry underwater welding. 

In the case of dry welding, for instance, the hyperbaric chamber is first filled with an inert gas mixture to control the environment, thus protecting the welder and leading to improved weld quality. In most cases, this is a blend of oxygen and helium. 

In the more dangerous — and slightly less effective — wet welding process, too, gases serve a purpose. Shielding gases are a must, for instance, when working with an electric arc welding rod. The air bubbles released around the arc are usually a mixture of hydrogen, carbon dioxide and carbon monoxide. 

These shielding gases protect the weld area from water and oxidation. This is especially critical as if oxygen does manage to seep through, it can cause cracks in the weld.

Dive Deeper into Welding Processes with nexAir

By this point, it should be clear why underwater welding is such a high-stakes — and extremely financially rewarding — profession. Without the right KnowHow or ideal blend of gases, welds can be exposed to contaminants, and welders are placed at a higher risk of falling sick.

At nexAir, we believe the safety of welders is of paramount importance. This is why, for over 80 years, we’ve made it our mission to help industries across the Southeast Forge Forward with only the highest quality welding supplies.