Few are aware of underwater welding. This welding process comes as a surprise to many as electricity and water appear to be a hazardous and incompatible combination. However, underwater welding is a lucrative field and one of the most well-paid occupations for commercial divers.
Also called hyperbaric welding, underwater welding was invented in the early 1930s and is still used for maintaining and repairing fully or partially submerged marine structures. Inland hyperbaric welders can work on small seacraft, dams and bridges. On the other hand, offshore welders have to work on ships, oil rigs, pipelines and underwater habitats. They may even have to perform welding work on nuclear power facilities.
What is Underwater Welding?
Underwater welding process is quite similar to welding on land. Both types of welding employ the same basic equipment and techniques. Hence, many underwater welders get trained to become professional welders before learning commercial diving.
There is no doubt that underwater welding is a dangerous occupation. However, with the right precautions and safety standards, many risks can be significantly mitigated.
If you are interested in learning welding techniques, you should enroll in a renowned welding school that offers training through experienced and certified instructors. After that, it is necessary to obtain training from an accredited institution for commercial diving. It takes at least a few years of training and work experience to become a proficient underwater welder.
Risks
Most people know that salt water is a good conductor of electricity. Water poses the risk of electrocution since it can act as a conducting path for current. Hence, we avoid wet surfaces that may be close to the sources of electric power.
Underwater welding, therefore,can be perilous. Although this is one of the threats involved in the occupation, it is by no means the biggest risk. You might be surprised to learn that other factors pose a far greater threat.
Rewards That Match Risks
Due to the challenging nature of the job and risks involved, underwater welding is a highly paid occupation. According to the Bureau of Labor Statistics, the mean annual wage of commercial divers is around $59,470. The Bureau includes undersea welders under the heading of commercial divers.
The mean hourly pay is $28.59, which is quite rewarding. The employment opportunities are also growing at a rate of 9.5%. This shows that underwater welding is a rapidly expanding field with bright scope and potential. Wages are rising at a rate of 3.5%.
Depending on how fast you learn and develop your skills, you can expect significant wage increases in a relatively short time. The top ten percent workers are earning in excess of $100,000 per annum.
In fact, the top ten percent of the most well-paid underwater welders can earn more than $150,000 per annum. This is one of the best paid jobs that you can get without a college degree.
Types of Underwater Welding
There are two basic categories of underwater welding:
Dry Welding
People normally visualize underwater welding as a job that is performed with the diver fully submerged. This is true to some extent. However, most underwater welding is done under dry conditions.
In dry welding, a hyperbaric chamber is deployed to provide a dry environment. Instead of being done in the presence of water, dry welding is performed in a dry atmosphere that composes of a mixture of gases. Dry welding ensures higher quality and reliability.
However, hyperbaric chambers do not come cheap and underwater welders may not always have access to them. Therefore, under some circumstances, diver-welders must rely on wet welding when dry welding is not possible.
Wet Welding
Wet welding can be performed based on a number of factors. It depends on the urgency of repairs and level of access to the welding region. However, it is best to consider wet welding as a last resort. There are a number of reasons for this. First, there is the obvious risk of welding in the presence of water. There is also the risk of quality issues due to wet welding. The welded joint may cool down too quickly due to rapid heat dissipation to the surrounding water. Quick cooling increases the risk of cracking and other joint defects. For the most reliable, durable and defect-free welded joints, the cooling rate must be carefully controlled. This is not possible while the process is carried out in the presence of water.
How Is Underwater Welding Done?
Diver-welders have a range of options at their disposal to carry out the welding task. Depending on the task provided, skilled underwater welders and project managers should discuss the most appropriate welding process to fulfill requirements.
Here are the different welding processes that can be used.
Wet Welding
Shielded metal arc welding, which is also known as stick welding, is a popular choice for wet welding. It is versatile and cost-effective. Using this method, welders create an electric arc using a consumable electrode that is energized by power supply. The arc is created between the electrode and structure being welded so that the filler material is melted and deposited at the joint.
To perform this welding process efficiently and safely, diver-welders must ensure that the electrodes and base metal surface are clean. Prior to performing the weld, the diver should inspect the area for obstructions or any other safety hazards.
When everything is ready, the diver-welder signals the team to switch the power on. The power source can generate 300 to 400 amperes of direct current. However, initiating the electric arc requires a fair amount of skill.
At this point, you may be wondering how the diver does not get electrocuted by the massive current being generated. The key to this lies in the layer of gaseous bubbles that are generated when the arc melts the flux. This layer shields the weld and prevents electricity from being conducted beyond itself.
Although these bubbles create an insulating layer to protect the diver against the current, they create a number of problems. These bubbles obscure the welding area, that is, they lower the welder’s visibility. These bubbles may also disturb the welding pool if the diver is not careful. Hence, wet welding presents its own set of unique challenges to diver-welders.
Direct current is also used, which is safer for underwater applications as compared to alternating current.
Stick welding is definitely one of the more popular choices for wet welding. But, other methods are also commonly employed for wet welding.
Flux-Cored Arc Welding
This versatile welding method can be used for cast iron, nickel alloys and other kinds of metal alloys. As the name implies, the consumable electrode consists of a filler material tube filled with flux at the center. This electrode wire is fed automatically to create accurate and carefully controlled welds.
Friction Welding
This technique employs heat and friction rather than melting the filler material to fuse metal.
Dry Welding
As mentioned above, a hyperbaric chamber is used in dry welding for more reliable results. First, a seal is created around the region that is going to be welded. Water is then pumped out through hoses and replaced with a gaseous mixture, such as helium and oxygen.
After pumping out all water, the hyperbaric chamber is pressurized at the right level in order to prevent decompression sickness. The choice of welding method employed is influenced by chamber size. Divers can choose from the following welding techniques.
Habitat Welding
In this method, underwater welders operate in a small chamber, which is called a positive pressure enclosure or a habitat. This method is used to carry out hot work. That is, this method creates an environment that reduces the threat of combustion posed by the influx of flammable vapors and gases. As a result, this technique is often used in offshore oil rig welding where such scenarios are common.
This method works by pumping in gases continuously to maintain a breathable atmosphere. As the name suggests, the pressure within the chamber will be higher as compared to outside pressure. As a result, gas is continuously flowing out of the chamber. This pressure difference is very small. The inside pressure is just .007 pounds per square inch greater than the outside pressure.
This creates two major advantages. The first is that it prevents the influx of combustible hydrocarbons and other dangerous gases. The second advantage is that toxic welding fumes can be maintained at safe levels. Due to the positive pressure difference, the outgoing gas carries off the toxic welding gases with it. The hazardous welding fumes within the chamber are further diluted by the inflow of fresh breathable gaseous mixture. Helium mixtures may be used to pressurize the chamber so that divers don’t suffer from nitrogen narcosis and become unconscious.
Prior to the diver’s entry, the water in the chamber is emptied so that breathable gases can be pumped in. Larger habitats are capable of accommodating two to three divers.
Pressure Welding
This welding method employs explosive force and/or friction to join workpieces under high pressure. It is also known as solid-state welding. Pressure welding is a broad term that includes different welding techniques that have one factor in common. They use mechanical pressure at the weld section to join them.
The generic term can include different processes, such as explosion welding, ultrasonic welding, diffusion welding, resistance welding, friction welding and gas pressure welding. The friction stir welding process is becoming increasingly popular. This process can enhance the joint quality by employing a rotating tool, which creates friction under strong forces to weld joint sections.
Dry Spot Welding
Dry spot welding technique is utilized for small chambers. The chamber is placed on the welding area to create a dry atmosphere. The diver carries out welding by placing the electrode within this chamber. Good sealing is necessary to keep out the surrounding water.
Dry Chamber Welding
Dry chamber uses a small-sized chamber to accommodate only the upper body of the welder. The diver must enter this chamber from the bottom. The chamber covers only the head and shoulders.
In dry welding, flux-cored arc welding and shielded metal arc welding are also often employed. They have been explained above briefly. Other methods that are often used include the following.
Gas Tungsten Arc Welding
This welding process is commonly known as ‘TIG’. The distinguishing feature of this technique is the non-consumable tungsten electrode. This electrode is used to create a high temperature electric arc. Another wire is also used as filler material. The welder melts the filler wire using the arc. The molten metal is carefully deposited on the joint section to create the weld. This technique works well for a large variety of alloys. TIG welding is known for its high quality and durable welds. But this method also requires a high degree of skill and precision since both hands must be used.
Gas Metal Arc Welding
This welding procedure is also known as MIG. The filler wire is automatically fed by means of a welding gun. The welding gun also pumps shielding gas to protect the hot weld. Since the welder can use both hands to hold the welding gun, this process is simple to master. Even new users can start making high quality welds straight away.
Plasma Arc Welding
This welding method is somewhat similar to TIG welding process. Plasma arc welding creates an electric arc between the workpiece and electrode that is usually made from sintered tungsten. PAW differs from TIG welding in one key aspect. The electrode is located within the torch body. Plasma arc can then be kept separately from inert gas. Plasma is injected through the copper nozzle at high speeds. The fine-bore nozzle restricts the plasma along one direction for accurate results. The temperature can go up 50,0000 F and even more.
For extensive underwater welding deep below the water level, underwater welders must work in pairs within the hyperbaric chamber. First, the hyperbaric chamber is lowered to the right depth and filled with breathable gases. Using a diving bell, the diver goes down to the same level, enters the chamber and starts welding. Shifts can last between six and eight hours.
Underwater Welding Dangers
Underwater welders face much greater dangers compared to land-based welders since there are many variables that can complicate matters. Different factors must be considered for safety purposes, such as gas pressure, water pressure, diving equipment, specialized welding equipment, restricted space, power supply and more.
Underwater welders work in remote and dangerous locations, such as offshore oil rigs and pipelines. Although this work is financially rewarding, it is also one of the most dangerous jobs. The fatality rate for underwater welding is one of the highest even among the most dangerous occupations.
If proper care is not taken, a small mistake can easily lead to death or long-term health complications.
Project managers and engineers should coordinate with underwater welders to address safety concerns. The following are the greatest dangers faced by diver-welders.
- Drowning. If the scuba gear fails in any way, the diver can drown if he or she is too deep below the water surface.
- Explosions. Combustible mixtures can be created from flammable gases like oxygen and hydrogen. If these pockets grow too large and are ignited, the resultant explosion can be lethal. This poses a serious risk to diver-welders.
But keep in mind that land-based welders also face the risk of an explosion if they are working in a poorly ventilated space.
To prevent the build-up of combustible gases, the welding space should be well ventilated for both surface and underwater welders.
- Electric shock. Electrocution remains a serious threat due to the large currents involved in welding. All equipment used for underwater welding must be waterproof. Keep the equipment well maintained. Make it a habit to always test the equipment prior to use. Make sure that there are no leaks in any equipment. Equipment should also be properly insulated.
As you can expect, underwater welding equipment will be slightly different as compared to land-based welding equipment. Wet welding requires double insulation for wires. Alternating current is never used in wet welding. Only direct current is utilized.
A knife switch is also present to turn off the power to the welding stinger.
- Lung, ear and nose damage. You should be careful of spending too much time deep underwater. This can lead to long-term health issues related to the nose, lungs and ears.
- Decompression Sickness. This is also called diver’s disease. This occurs due to the inhalation of gases at different pressures. Decompression sickness can prove to be fatal in extreme cases.
- Marine wildlife. Although shark attacks are not too common, divers must be wary of sharks and other deadly marine animals.