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Underwater Welding: Protocol and Equipment - Tuesday, January 26, 2016

Hyperbaric/Underwater Welding

Underwater welding has two distinct forms: wet welding and hyperbaric welding. Both require specific commercial dive gear. Here's a look at how these procedures, and their equipment, differ.

Hyperbaric/Underwater Welding

Wet Welding

Since oxygenated water would create a porous and brittle weld, wet welding is not actually performed in direct contact with the water surrounding it. The weld site is underwater, but the stick-welding commercial dive gear, and the processes involved, create a small bubble of hydrogen gas that protects the weld from the water's damaging effects. This gas creates a 'flux' that covers the weld site, and protects it while it cools.

Underwater welders are highly trained for a reason. Not only does the electric arc from the commercial dive gear welding stick generate massive amounts of heat, but it also creates a large number of bubbles, making it near impossible to view the actual weld's location. Through extensive training and practice, underwater welders learn to operate blind, guessing the distance and level of penetration.

Commercial dive gear for wet welding requires a specific wet-welding power system that leverages double-insulated wires connected to the stinger. The task also requires a knife switch, and solely direct current.

Hyperbaric Welding

Hyperbaric welding, also known as 'dry' welding, is a different beast entirely. Unlike wet welding, which operates in a wet environment and uses tools to remove water from the weld area, hyperbaric welding takes place inside an underwater, pressurized room. This site separates surrounding water from the welding area. The room needs to be pressurized due to its position below sea level, in order to compensate for the increased pressure outside the room. By filling the room with gas, operators can pressurize the room to make up for the pressure-related depth.

While this may seem similar to dry welding performed topside, there are unique and critical differences. First, hyperbaric welding is highly pressurized (0.7% lbs/square inch), as opposed to the regular atmospheric pressure of traditional dry welding. This means welders need to set their air volumes to match the pressure of the surrounding water. Second, this form of dry welding takes place in an underwater 'habitat' that generally fits tightly around the welding space. Third, it is very expensive. The expense is due to the total cost of the room, its upkeep, maintenance, and gas and power bills.

In regards to equipment, dry welding leverages a singular insulation system to run the power cables.

Is It Dangerous?

Underwater welding may sound threatening, but the risks are minimal. The danger is similar to that of any deep diving work. In other words, underwater welding isn't the most dangerous type of commercial diving.

Where to Start?

Underwater welders, whether they do wet or hyperbaric work, require several tools. They have to purchase or rent commercial dive gear and underwater welding equipment. Aqua-Air provides these necessities and more. Be sure to check out our website for more information on our products and services.


 

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