How Does Underwater Welding Work - Everything You Need To Know

Underwater infrastructure has been expanding as early as the 1800s. As the number of objects in water (partially or completely submerged) such as pipelines, oil rigs, nuclear power infrastructure increased, so did the need for underwater maintenance and repair work. To fulfill this demand, a new occupation arose in the 1930s called underwater welding.

Most of us know underwater welding as one of the most dangerous but lucrative jobs in the world but there’s a lot to learn about this unique and important occupation. In this guide, we’ll talk about what exactly is underwater welding (definition), the types of underwater welding, how it works, the dangers and rewards associated with this type of welding, and the job market.

What is Underwater Welding?

Underwater welding is also referred to as hyperbaric welding or sometimes as marine or deep-sea welding, although these terms have slight differences, they are often used for the same broad activity with the same underlying principles. 

It was invented by Soviet engineer Konstantin Khrenov in 1932 and was adopted by the US Navy in the 1940s. Soon enough, this technique was proliferated and its uses expanded from military to marine life, construction, etc.

The biggest question people have is how can welding be done in the presence of water. It goes against the very fundamentals we’ve learned – water and fire/electricity do not mix very well at all. But you know what surface welding is, then underwater welding is a simple concept to understand. 

Though there are some techniques that cannot be used, underwater welding (especially hyperbaric welding) uses mostly the same equipment and the same techniques as dry land welding.

The only major difference is that underwater welders will either use a hyperbaric chamber or waterproofed welding tools such as welding rods coated with a waterproofing material, depending on the type of underwater welding.

Types of Underwater Welding?

Underwater welding can be differentiated into two main categories: dry welding (or hyperbaric welding) and wet welding.

Dry Welding (Hyperbaric Welding)

Don’t let the name confuse you, dry welding can still be done underwater, with the help of a hyperbaric chamber. A hyperbaric chamber is a tool that covers and seals the entire welding surface and replaces the water with gases. This gives welders a dry environment to their welding like they would on the surface.

Wet Welding

Since hyperbaric chambers are often expensive, a lot of underwater welding is still done under wet conditions. Wet welding is very challenging but possible with some modifications to the welding tools. 

For instance, the welding rod is covered with a waterproofing material that ensures the powder flux stays dry. The polarity is also set to reverse to ensure the electric current flows away from the welder. Furthermore, to prevent electrocution, a thick layer of gases is created around the electrode to ensure that electricity doesn’t come in direct contact with the water.

Wet welding is more versatile and cost-effective but it is not the preferred or first choice for underwater welding. The welds created through wet welding have a greater risk of developing cracks and thus wet welding is done when hyperbaric welding is not possible.

How is Hyperbaric Welding Different from Underwater Welding?

Even though the two terms are often used interchangeably, it’s important to know that there are differences between hyperbaric and underwater welding and they can be used to denote two different things.

Hyperbaric welding refers to a type of welding that is done inside a hyperbaric chamber in a pressurized environment. The pressurized environment is usually underwater but since the actual welding process takes place inside the chamber, hyperbaric welding is very similar to dry or surface welding.

Underwater welding, on the other hand, specifically refers to wet welding or welding that takes place in direct contact with water.

How Does Underwater Welding Work?

Underwater welding can be done through various methods and techniques. The welders and supervisors will choose the best method depending on a number of factors including the location of the project, the type of weld required, budget restrictions, etc. That said, underwater welding processes fall under one of two categories: dry and wet welding.

Dry Welding

Dry welding works by creating a surface-like atmosphere where there is no water. This is done by attaching a hyperbaric chamber to the welding object and creating a waterproof seal. 

The chamber has hoses connected to it that remove all the water inside the chamber and fill it with common atmospheric gasses like oxygen and helium. Once the water has been removed, the chamber is pressurized to prevent decompression sickness. 

Depending on the size of the chamber required, welders will choose from one of the following types of hyperbaric welding:

  • Pressure Welding: The hyperbaric chamber is pressurized to be the same as sea-level pressure.
  • Habitat Welding: The hyperbaric chamber is almost a room-sized chamber known as the habitat which is pressurized to be at the same level as the outside water (ambient pressure). The habitat has hoses that flush out all the water before the divers begin welding.
  • Dry Chamber Welding: Similar to habitat welding but instead of a small room, the chamber is much smaller and covers all the welder’s head and shoulders.
  • Dry Spot Welding: The diver swims into the chamber from the bottom which covers the diver’s head and creates a seal.

Since dry or hyperbaric welding uses hyperbaric welding and creates a dry or surface live environment for welding, welders will often use the same basic welding processes for underwater welding as they do for surface welding. 

Gas tungsten arc welding is the most commonly used method for dry welding, although other methods like shielded metal arc welding (SMAW), flux-cored arc welding (FCAW), gas tungsten arc welding (GTAW), gas metal arc welding (GMAW), plasma arc welding (PAW) can all be used.

Despite the technological improvements in the past few decades, dry welding still suffers from a few limitations. For instance, as the pressure increases (by going deeper into the water), the overall efficiency of the welds decreases. 

That said, hyperbaric chambers have been tested at depth as low as 2,500 m (8,200 ft) although, in practice, hyperbaric welding is limited to less than 400 m (1,300 ft) due to psychological and practicality reasons.

Wet Welding

In wet welding, the electrode and the welder are in direct contact with the water. To protect the welder and weld, certain changes are made to the same welding processes that are used on the surface. 

Some of the modifications include:

  • A waterproof electrode is used instead of a normal electrode.
  • The welding power supply is connected to the welding equipment providing 300–400 Amps of Direct Current to the welder.
  • Stick electrodes are specially designed (insulated) to withstand water cooling and will overheat if used outside water.
  • Direct current is used rather than alternating current as it provides better efficiency.
  • Gas bubbles are used around the arc to prevent accidental electrocution.

One of the most popular welding techniques used underwater is Shielded Metal Arc Welding (SMAW) or stick welding. SMAW is one of the more affordable and versatile welding methods that work well underwater infrastructure that is made with stainless steel and aluminum. Other less common methods include Flux-cored Arc Welding (FCAW) and Friction Welding (FW).

Like hyperbaric welding, wet welding too suffers from limitations, the biggest of which is rapid cooling. Since the water a lot cooler than the weld and becomes increasingly cold as depth increases, it rapidly cools down the weld which is almost completely exposed to the elements. This results in lower-quality welds that can even develop cracks.

Dangers of Underwater Welding

Underwater welding almost always makes an appearance on the top lists of most dangerous professions and this is for a reason. Despite the numerous safety precautions and standards adopted in the past few decades, there are still some inherent dangers to welding that make it a profession with one of the highest number of fatalities. 

In fact, according to research conducted by OSHA, 50 out of every 1,000 diver-welders were expected to have a fatal accident in their working lifetime, which is a suprisingly high death rate, 40 times higher than the American average.

Some of the major underwater welding risks include:


Being surrounded by water from all sides, one of the biggest dangers posed to welder-divers is electrocutions. Electric shocks from welding supply chains can be lethal on the surface and even more so underwater. 

Electric shocks can be a result of welding equipment that’s not prepared properly or broken. Furthermore, the electric arc becomes unstable and erratic when used in fresh water which puts inexperienced welder-divers at a greater risk.


All types of welding use various gases for different reasons. However, under certain conditions, these gases can ignite and cause explosions. For instance, hydrogen and oxygen can combine and lead to explosions which are sometimes lethal.

Experienced diver-welders with greater spatial awareness are more adept at avoiding these explosions as they can catch sound bubbles popping. These bubbles are caused by the gasses that are formed when hydrogen and oxygen mix. Welding is stopped as soon as popping sounds are heard.

Decompression Sickness

Decompression sickness is a diving disorder, often seen among divers and underwater welders. Decompression sickness happens when a welder-diver ascends quickly from the deep body of water. 

In the depths of the water, the gasses that the diver inhales are high-pressure which results in nitrogen in the blood. If the diver ascends slowly, the body has enough time to remove the nitrogen from the blood.

However, in certain cases (during an emergency, for example), the diver-welder may be forced to quickly abandon post and reach the surface. In such a case, the nitrogen separates from the blood and turns into nitrogen bubbles that can cause rashes, joint pain, paralysis or in worse cases, death.


Despite years of training and swimming experience, diver-welders are still at the risk of drowning. This risk arises due to a number of factors including:

  • Lack of proper or broken equipment (masks, oxygen tanks, etc.)
  • Tangling with underwater objects such (pipes, hoses, or chains)
  • Sudden change in water pressure (differential pressure) that prevents a diver-welder from ascending.


Even though for longer projects, a team of welder-divers is sent who work in shifts, there is a risk of prolonged exposure to the cold which can result in hypothermia as a single shift can last up to 6-8 hours at a time. In cases of extreme hypothermia, the diver-welder can suffer from organ failure and death.

Other Dangers of Underwater Welding

Other less common dangers that still have a psychological effect on the diver include:

  • Marine life: Though shark and attacks by other deadly marine animals aren’t very common among diver-welders, they still pose a danger, and divers must be on the lookout for any marine life that could interfere during welding.
  • Long-term health issues: Underwater welding can also result in various long-term health complications, including lung, ear, and nose damage.

Safety Precautions for Underwater Welding

To avoid accidents, certain best practices, safety precautions, and standards have been established. Here are some precautions that a welder-diver can take to protect themselves:

  • Ensure not to come in between the welding work and the ground clamp.
  • Use a “knife switch” that allows a supervisor or diving partner to stop the flow of electricity in case something is wrong.
  • Wear properly insulated rubber wetsuits to reduce the loss of heat and avoid hypothermia.
  • Ensure all equipment is working as intended before setting off.
  • Understand and learn the right procedures to protect oneself from the Delta P hazards.

How to Become an Underwater Welder?

Most underwater welders start out as ground welders with past experience in diving. As they became more proficient in welding, some apply for certifications that would allow them to take on underwater welding jobs. 

The most important skill apart from welding itself is diving. Underwater welders need to proficient divers. When an underwater welder is fully concentrated on the welding, diving needs to be second-nature.

However, if you’ve never done welding or have a professional swimming experience, your journey will be longer. Most people would have to do the following five things in order to become an underwater welder:

  1. Get a high school diploma or G.E.D.
  2. Earn the relevant certifications as well as experience in ground welding
  3. Pass a commercial dive physical exam
  4. Continue earning certifications and improving your commercial diving skills (underwater welding is a competitive field)
  5. Earn a commercial diving position

After doing all of these things, you can begin applying for underwater welding jobs. However, keep the timeframe in mind as doing all of this would take the better part of a decade or more.

How Much Do Underwater Welding Jobs Pay?

Even though most of the dangers of underwater welding can be avoided through knowledge and preparation, it’s impossible to completely remove the possibility of accidents and underwater welding salaries reflect that. Underwater welding jobs are among the highest-paid welding jobs, period.

The most lucrative underwater welding jobs can pay upwards of $300,000, although these are rare and will likely require you to be posted on-site for the entirety of the year. The average welding jobs pay around $26 per hour or $54,000 annually. Furthermore, beginner welders average around $30,000 annually while the top 10% of underwater welders earn around $84,000.