You must have heard about ‘Welding’, but have you ever heard of ‘Underwater Welding‘? Sounds interesting, doesn’t it? Underwater welding is a broad concept, and to understand it, we have to know many things about it.
1. Underwater Welding
As we all know, welding is the method of coalescing or fusing two or more parts of metals by using heat or pressure, or both depending on the properties of the metal to be welded. These parts, after heating at high temperatures are allowed to cool down fusing the parts.
So Underwater Welding process is welding that is done at elevated pressures underwater. It is a type of Hyperbaric Welding invented in the 1930s. It is quite similar to the welding done on land. This is why underwater welders get professional training in welding first and after that become commercial divers.
This is one of the welding processes/techniques used for the maintenance and repair of completely or partially submerged underwater structures and machines. It is an important technique for underwater welders for petroleum industries for repairing pipelines, submerged parts of the ship, and offshore drilling oil rigs.
2. Types of Underwater Welding
Underwater welding can be broadly categorized as dry underwater welding and wet underwater welding. There are further different types of dry and wet underwater welding.
2.1 Dry Underwater Welding
Dry underwater welding, also known as habitat welding in some cases, is the technique of welding underwater using a hyperbaric chamber. In this technique, the site to be welded is sealed by a chamber from which the water is flushed out using hoses and pipes. The emptied area is simultaneously filled with gases in vapor form like Helium and Oxygen.
In this way, welding is performed in a dry environment just as in the case of land welding. This method is almost similar to welding in the air. Welding using this technique is both money and time saver as wet underwater welding requires specialized machines to work in the marine environment. Dry underwater welding is further classified into four types.
Pressure welding is a kind of underwater welding where the metal pieces to be joined are welded under pressure by heating them using friction (Friction welding), explosion, or using electrical current (Resistance welding), also known as solid-state welding.
Pressure welding is used in vehicle construction in Automobile industries, aerospace industries, energy and renewable energy industries, oil rigs, mechanical plants, and engineering and, white goods industries.
Dry chamber welding, as we talked about earlier, is simply the method of welding in an underwater environment by creating a dry chamber around the welding area and giving high-quality results. This area now filled with gases helps to do welding in the same way as it is done on land. In dry welding, an empty area is created, which is enough for a diver to enter his head and shoulder and do the work.
In this underwater welding technique too, an empty area is created around the spot to be welded. But in the case of dry spot welding, space is enough for the diver to get his hands inside and do the job. After that, the welder enters his electric arc and heats the surfaces to be fused, thus welding them.
In Habitat Welding, the chamber created around the welding site is not subjected to higher pressure. The pressure inside is kept similar to the surrounding pressure, and water is pumped out of it. These chambers are known as welding habitats or hot work habitats. In the presence of explosive gases in vapor form, this chamber provides the welder with safety.
Suggestion box: – Method of Dry underwater welding/Metallurgy.
2.2 Wet Underwater Welding
In wet underwater welding, the welder, along with the electrode, is directly exposed to the surrounding water. The electrodes used in wet welding are waterproof, and the electrode holders are heavily insulated and manufactured for water cooling.
A constant one direction current welding machine is used in wet welding which can heat up rapidly when used in air. Dry welding is preferred over wet welding because, in the case of wet welding, the cooling of the welded area takes place quickly, which can lead to an increased risk of cracks and other joint defects.
For reliable, defect-free, and long-lasting welded joints, the cooling rate must be regulated. This isn’t easy to do in wet underwater welding as the heat gets dissipated into the surrounding water. Therefore, wet welding is dependent on the level of access and degree of urgency of the welding region. Due to many factors, this technique is kept as a last resort in order to get higher-quality welding.
There are two types of wet underwater welding, flux-cored arc welding, and friction welding.
The flux-cored arc welding process is an automatic or semi-automatic arc welding process developed in the 1950s. The heat produced by a DC electric arc is used to heat the metal surfaces to join them. This technique is similar to Metal Active Gas (MAC) welding. It requires a continuous wire-fed electrode, equipment similar to the MAC welding process, and a constant-voltage or constant-current welding power supply.
It was discovered as an alternative to SMAW or Shielded Metal Arc Welding in which stick electrodes were used, but their use was unnecessary. Flux arc welding excluded the use of these stick electrodes, thus eliminating many restrictions associated with SMAW.
This process of welding is used for welding stainless, mild, and low alloy steels, some wear facing/surfaced alloys, and some alloys having a high composition of Nickel.
This type of welding has many advantages like low chances of porosity after welding, convenience to move equipment, the high deposition rate process, and no requirement of shielding gas.
Friction welding is generally not preferred to be performed underwater because of the cooling properties of water. This causes poor quality of the weld, which includes excessive hardness and severe cracking. It is used for steel studs and steel welds.
Rotary friction welding is the preferred friction welding to be carried out underwater. In this technique, foamed plastic is used to form a shroud surrounding the welding area. This is used in the welding of underwater pipes. It was found that using the foamed plastic shroud on the outer surface of the pipe and a plug on the inner surface eradicates the hardening problems and gives acceptable welds.
So, these were the different types of welding according to a broad categorization. Many more new techniques are being discovered with time and advancements in technology.
3. Underwater Welders – Risks
Underwater welding is considered one of the most hazardous occupations for underwater welders. When underwater welders dive into deep depths to fix structural issues, they need to be fully prepared to cope with any mishappening. There can be oil leaks in the case of oil industries, pressure differences, and many other risks that can be fatal.
3.1 Shocks and Underwater Explosions
During underwater welding, hydrogen and oxygen are produced, which when combined in concentrated amounts can lead to lethal explosions. This is without a doubt one of the most dangerous jobs. As we all know, water is an excellent conductor of electricity, and the use of electric equipment like electrodes, and an electric arc causes a great threat to divers. Therefore, the divers are required to wear specialized waterproof costumes and equipment.
Almost all if not many underwater welders that have traveled in an airplane have suffered from intense ear pain due to a change in normal pressure. Similarly, if someone goes underwater, he/she will suffer from such discomforts again due to pressure changes.
When a diver dives into great depths, an increase in pressure can cause permanent or temporary hearing impairments or lung damage.
Most drowning incidents take place due to undetectable differential pressure until it is too late to evade. The pressure difference can change quickly from hundreds of pounds per square inch which makes it difficult for the diver to escape. Failure to drive gear such as leaking in oxygen tanks, masks, or hoses can also lead to drowning incidents.
The underwater temperatures are shallow. When a diver dives into heavy depths, rapid heat loss from the body can lead to hypothermia. This can cause metabolism issues and organ failures. This is why divers are instructed to wear well-insulated rubber wetsuits for defense against extreme temperatures.
3.6. Decompression Illness
The underwater welders have to travel many feet beneath the surface of the water to reach welding sites. This exposes them to severe pressure changes. This illness happens when they clamber too quickly from high-pressure to low-pressure zones. This leads to nitrogen gas bubbles entering the individual’s bloodstream, which can lead to two potential health risks: decompression illness and arterial gas embolism. This can lead to tissue damage, skin rashes, joint pain, blockage in blood flow, paralysis, or even death.
3.7. Environmental Impacts
The light produced during welding attracts the planktonic creatures, which as result attract different fishes. This can lead to hindrance in the welder’s work and can also harm marine life causing the death of fishes and other marine creatures.
Read more about the solemn issues regarding the environment – Top five immediate concerns about the environment.
Underwater welding is a highly paid occupation and an elite career choice that involves lots of underwater adventure and traveling. Underwater welders are also called offshore welders, and they are required to have both welding and commercial diving skills.
There is no age bar to applying for an underwater welder; however, some special certificates are required to get in no matter how much experience you have. For being an underwater diver, you need to have a commercial diving certificate. The commercial dive certification involves some supplementary requirements over common certification, which cannot be overlooked.
Qualification requires the ability to use commercial grade equipment used in underwater welding, underwater inspections, hyperbaric chamber undertakings, diving physiology and communication, and emergency procedures. One also has to be a certified commercial diver and pass through various physical examinations as the companies recruit candidates who are in good physical health.
Many commercial diving schools offer commercial dive certifications under the commercial diver program. The Commercial Diving Academy in the United States provides internationally recognized welding training in this field. They are required to keep their certifications updated by taking periodic physical tests.
4.2 Job Duties of Underwater Welders
There is a general list of duties that all the underwater welders should be able to perform. These duties for many underwater welders include underwater cutting, fitting, drilling oil rigs, underwater photography, inspection, and non-destructive testing and drafting. The underwater welders should be highly qualified and competent for project management posts.
4.3 Salaries of Underwater Welders
The pay of an underwater welder is judged based on the project undertaken. This includes many aspects of the underwater welders like the length of the project, dive methods and welding techniques employed, and the hazard levels. Qualifications and posts are other parameters that govern an underwater welder’s salaries. According to the data collected from commercial divers and global statistics, an underwater welder earns $53,990 annually or $25.96 per hour.
The top 10% of dive welders who have high qualifications and experience can make up to $83,730, while the bottom 10% of dive welders who are new in this occupation and don’t have much experience can make up to $30,700. The average salary of underwater welders is $64,486, this career option pays you a decent amount of money and reputation. To know about the occupational employment statistics, read the statistical data by the American welding society- U.S. Bureau of Labor Statistics.
5.1. What Is Hyperbaric Welding Used For?
The process of welding at high pressures, usually underwater, is known as hyperbaric welding. Hyperbaric welding can take place either wet in the water or dry inside a specially constructed positive pressure enclosure, resulting in a dry atmosphere.
When employed in a dry environment, it is commonly referred to as “hyperbaric welding,” and when used in a wet setting, it is commonly referred to as “underwater welding.” It has a wide range of applications, including ship repair, offshore oil platform repair, and pipeline repair. Steel is the most often welded material.
5.2. Is TIG Welding Stronger than MIG?
TIG welding, also known as Gas Tungsten Arc Welding (GTAW), is the process of welding with an electric arc and a tungsten TIG electrode that does not dissolve or burn off. TIG welding is just melting metal together without the use of filler metal, as is MIG welding.
TIG, as opposed to MIG welding, may reach this level of precision because the operator has more control over the gun. Unlike the MIG gun, which contains both the electrode and the filler metal in one system, It forms the arc with a non-consumable tungsten electrode.
5.3. What is Plasma Arc Welding?
Plasma arc welding is an arc welding procedure in which heat from a constricted arc is established between a tungsten/alloy tungsten electrode & the water-cooled nozzle (non-transferred arc) or between a tungsten/alloy tungsten electrode as well as the work is used to generate coalescence (transferred arc).
Plasma Arc Machining (PAM) Systems are classified into two types: Transferred Arc PAM Systems and Non-Transferred Arc PAM Systems. The plasma arc is transferred between the electrode and the workpiece in a Transferred Arc PAM system.
5.4. What Is the Underwater Welding Equipment Required?
When it comes to underwater welding equipment, a diving knife is sufficient. The umbilical cord is where gas is pumped from and to the diver. Harness – Used to keep the diver afloat and in one place while doing his or her duties. Gas Panel and Compressor: A competent underwater welder monitors gas gauges and ensures a consistent supply of air is delivered to the diver(s) below.
We hope you found this article informative and enjoyed reading it.