Underwater welding is one of the most dangerous occupations in the world. Underwater, the odds are stacked against you. The pressure threatens to crush the body. Clouds of bubbles making any task difficult to perform by blocking visuals. Despite the dangers, thousands take on the responsibility of installing underwater structures. Underwater welders are responsible for repairing pipelines, offshore oil drilling rigs, ships, dams, locks, sub-sea habitats and nuclear power facilities, to name a few.
[Image Source: U.S. NAVY]
How to weld underwater
Binding two pieces of metal underwater involves a lot of consideration towards safety. There are a few ways welders approach the task. In most cases, and most ideally, a dry chamber system is used. Temporary hyperbaric chambers are used to prevent water from entering the work area. The chambers house up to three welders at a time.
Fans controlled by a ground crew consistently exchange exhausted air and replace it with new air. The cabins are pressurized to minimize the effects of pressure sickness. More on that below.
Alternately, there is wet welding, a practice used mostly as a last resort. The method which is chosen depends on the ease of access to the area and the level of severity.
Wet welds run the extra chance of cooling down too quickly by the water, increasing the chance of cracking.
“Wet welding is an emergency or temporary thing,” explains underwater welder Jeff Peters.
The job requires working in daunting environments deep underwater with minimal visibility. Underwater welder Peters warns “The places you’re working are very dark and very cold.”
[Image Source: Divers Institute of Technology]
How does it work?
Using electricity underwater seems incredibly dangerous, which it is, but not necessarily from the electricity. Most underwater welding is performed using stick welding which uses an electric arc as the source of energy.
When wet welding, a thick layer of bubbles are created as the flux on the outside of the rod evapourates. The gaseous layer serves to shield the weld from water and other oxidizing compounds.
The surprising danger of underwater welding
Of course, as expected, underwater welding is incredibly dangerous. Though many water flow hazards impede diving operations, some of the largest dangers to underwater welders may be surprising.
One of the most dangerous hazards to divers are known as “Delta P” hazards (ΔP). Delta P, or differential pressure, presents a unique and potentially fatal hazard to divers. The differential pressures occur when two bodies of water intersect, each with a different water level, such as the water levels at a dam.
The difference in depth creates a pressure difference as water attempts to rush from one body to the next with great force. Furthermore, Delta P’s are nearly undetectable until it is too late to escape The pressure difference can accumulate to hundreds of pounds per square inch making them tough to escape. Consequently, a diver who becomes trapped in the bottleneck of the flow has an incredibly high risk of drowning.
Proper preparations and practices need to be considered before the operation is to be executed safely. If the safety procedures are not stringently enforced, fatal accidents are likely to occur.
“If a diver is using a scuba tank, has no support staff or communications equipment and is not tethered to the surface—the opposite of the typical scenario involving certified commercial divers—he could run out of air while trapped, or hypothermia could set in.”
The future of underwater welding
Underwater welding is one of the most difficult jobs on the planet and in the water. Though with advancing technologies in robotic capabilities, advancements are being made to protect underwater welders. Despite what the future may hold, today underwater welders help maintain the most integral components of many industries around the world. Until robots can perform the intricate tasks with the dexterity of a human, underwater divers will continue to be a necessity all around the world. It is a physically and mentally challenging job, though for what it creates in stress, it makes up for in the pride of maintaining the technologies in which the world relies on today.