Underwater Welding Dangers & Safety Measures


Safety first.

And last.

If you’ve ever worked under a diving adviser or taken a welding class, safety is the primary emphasis. Underwater welding may amplify dangers of surface welding. But only if you choose to work in ignorance. Use common sense.

Underwater welding is not the most dangerous job in the world. Not by a long shot.

We’re steering away from the rumors and looking at the facts.


Most diving classes and employers use safety manuals to explain these issues. Safety manuals bore people to death. That poses an extreme irony that I don’t wish to be a part of. Therefore, though I’ve based all information off of safety manuals, I’m only including the essentials:

  • Major threats posed to underwater welders
  • Safety tips to combat each threat

Keep in mind:

As a welder-diver, you are adopting not only the benefits but the risks of two professions. Also, risk can equate with underwater welding income.

Most of the dangers below pertain more to wet welding than dry welding, but all have application to divers.


Electric shock

Water poses little resistance to electricity, and if left ungrounded electric current will flow freely through water like a hot knife through butter.

All welder-divers face risk of electric shock, especially during wet welding since their entire atmosphere is composed of water. Welder divers that work in “splash zones” (areas intermittently covered by water) face even more risk given the exact position they must hold while they work – water waves can throw them off-balance and cause variables loosen their grounding cable. Three independent actions occur simultaneously to shock diver-welders:

  • Part of their operating equipment experiences electrical failure
  • Ground fault interrupter fails
  • Underwater welder goes between path of fault and earth ground

Electric Shock Safety Measures

Most preparation for underwater welder projects happens above, not below water. Proper equipment inspections are crucial to reducing risk of shock. Direct current (DC), not alternating current (AC), should be used to power welding equipment.


  • Wear rubber suit and gloves.
  • Glove gauntlets should firmly attach to wrists so no slag floats in.


  • Watertight and completely insulated. To insulate exposed parts, apply rubber tape, scotch cote then electrical tape.
  • Strain relief must be incorporated in cables at deeper water levels.


  • Use waterproofed electrodes that are fully insulated.
  • When electrode is powered or “live:” Never carry electrode around with you (if you’re already carrying it, don’t put it down suddenly – this may ground the charge through your body). Never change out the electrode.
  • Handle loose metallic items carefully so they don’t come in contact with electrode

Safety (Knife) Switch

  • Open only right before diver-welder is ready to power electrode.
  • Always use double-pole switches – they possess working and ground lead that close simultaneously to interrupt current.

Power Supply

  • Keep power supply on rubber or wooden platform.
  • Underwater equipment like lighting or hand tools may require AC power, but make sure each equipment piece has a ground fault interrupter attached.


Underwater welding produces gases (oxygen, hydrogen) that have explosive potential if combined in high levels. During wet welding, welder-divers may hear a small popping sound caused from hydrogen and oxygen bubbles traveling upward and collecting. This sound should serve as a warning to stop welding immediately to locate the area where gas is collecting.

Explosion Safety Measures

  • Look for any parts of work area that could trap gases overhead. If needed, use a vent tube to direct gases to the surface.
  • Weld from the highest to lowest point if possible.
  • Electrodes that exceed 10,000 degrees Fahrenheit in a gaseous environment may explode if a spark occurs.
  • Thick material: Work from outside and around circumference. Pull away electrode every few seconds and make brush action. You may want to allow water to enter weld to keep temperature down, though this reduces its quality.
  • If working on or above river beds, remember that mud may already have explosive methane gas trapped within it. And a river bed with cows nearby? Forget about it.


Diver Bends

Because many welder-divers work hundreds of feet underwater, they undergo pressure changes that can cause harmful effects on their body on their way up.

Decompression sickness or “the bends” happens when welder-divers make their journey to the surfacetoo quickly and pushes dissolved gases into other parts of the body through the bloodstream. Similar to putting your foot on a half-full balloon and creating bulges in odd places. Symptoms of the bends include dull pain, itching and fatigue in these parts of the body:

  • skin
  • lungs
  • ears
  • brain
  • joints
  • spinal cord

Diver Bends Safety Measures

To transport welder-divers to deep levels underwater, they use a pressurized cabin known as a “diving bell.” This bell will maintain appropriate pressure levels to help diver-welders’ bodies adjust. From the bell, diver-welders will work in either the water or a hyperbaric chamber. To decrease risk of decompression sickness coming up to the surface, diver-welders should avoid the following:

  • Ascending quickly after a deep dive
  • Continuous underwater dives in a few hours’ span
  • Flying quickly after diving
  • Becoming dehydrated
  • Drinking alcohol

In general, underwater welders only ascend about 33 feet per minute with proper decompression. Companies employing diver-welders follow rigorous guidelines for decompression using computers that calculate decompression rates for all their equipment, but diver-welders must still be aware of these procedures in case equipment malfunctions.

Other Hazards

In addition to decompression sickness, all divers expose themselves to various risks underwater. Although not as high profile in nature, welder-divers should prepare themselves for these risks:


Duh, right? Malfunction in breathing equipment such as your mask, hoses or oxygen tank(s) creates major problems for welder-divers, especially in situations where they cannot come to the surface quickly.


As a rule of thumb, the deeper the descent the colder it gets.

In addition to highly insulated scuba equipment, welder-divers should check for any small tears in theirdry suit and gloves.

If water penetrates your skin, your body temperature will quickly drop in a cold environment. In certain cases, saturation divers will use helium in their environment to reduce chances of decompression sickness. Because of helium’s thermal properties, divers must constantly monitor their temperature after absorbing large amounts of helium into their bloodstream. Hypothermia can onset in a matter of minutes.

Marine Life

Cue Jaws music – not really. However, light from welding can attract plankton, and plankton attract fish. Though marine life are not a major concern, they can get in the way of the welder-diver’s work and cause delays. Since increased time means increased risk, welder-divers should explore their work area beforehand to clear away any obstacles, including fish.

Looking Ahead

Because of the various operations and procedures of every organization involved in underwater welding, we could not create a complete list of dangers and safety measures.

It is my only hope to provide the most fundamental risks so as to educate individuals interested in pursuing a welder-diver career. Veteran welder-divers may need a “refresher” as well. Because underwater welding is only decades old, the long-term effects and dangers are unknown. Researchers continue to study the health and safety of welder-divers as they age. Their results will give us new information to apply.

Until then, we must go into the profession with the wonder and respect that it deserves.







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