Wednesday, August 4, 2021

Underwater Welding: All Exciting Details About It

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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.

So in this article we are going to read everything about what is underwater welding, how is it done and the career scopes involved with it.

1. What is 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 this fusing the parts. Underwater welding

So Underwater Welding is the process of 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 welding first and after that become commercial divers.

This technique is used for the maintenance and repair of completely or partially submerged underwater structures and machines. It is an important technique for petroleum industries for repairing pipelines, submerged parts of the ship, and offshore oil drilling rigs.

2. Types of Underwater welding

Underwater welding can be broadly categorized into 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 the water is flushed out using hoses and pipes. The emptied area is simultaneously filled with gases in vapour 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.

2.1.1 Pressure Welding

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). This technique is also known as solid-state welding.Underwater welding

This type of 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.

2.1.2 Dry Chamber Welding

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 gives high-quality results. This area now filled with gases helps to do welding in the same way as it is done on land.

In this technique, an empty area is created, which is enough for a diver to enter his head and shoulder and do the work.

2.1.3 Dry Spot Welding

In this underwater welding technique too, an empty area is created around the spot to be welded. But in 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 heat the surfaces to be fused, thus welding them.

2.1.4 Habitat Welding

In this method, 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 vapour form, this chamber provides the welder with safety. Underwater welding

Suggestion box: If you are interested in learning more about the method of dry underwater welding, then the following article – 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 this technique are waterproof, and the electrode holders are heavily insulated and manufactured for water cooling.

A constant direct current welding machine is used 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 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 this type of 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.

2.2.1 Flux-Cored Arc 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. Underwater welding

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. 

2.2.2 Friction Welding

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 most 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. Risks involved in Underwater Welding

Underwater welding is considered one of the most hazardous occupations. 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. As we all know, water is an excellent conductor of electricity, the use of electric equipment like electrodes causes a great threat to the divers. Therefore the divers are required to wear specialized waterproof costumes and equipment. 

3.2 Hearing and lung damages

Almost all of us who have travelled in an aeroplane has 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 damages. 

3.3 Risk of drowning

Most of the 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 in driving gear such as leakings in oxygen tanks, masks, or hoses can also lead to drowning incidents. 

3.3 Hypothermia

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 defence against extreme temperatures. 

3.4 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 into 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. 

3.5 Some environmental impacts

Human intervention in the environment always leads to consequences. The light produced during welding attracts the planktonic creatures, which in result attract different fishes. This can lead to hindrance in the welder’s work and can also harm marine life causes the death of fishes and other marine creatures.

Humans have a hand in the deteriorating environment in many ways. To read more about the solemn issues regarding the environment, read the article – Top five immediate concerns about the environment.

4. Underwater welding as a career option

Underwater welding is a highly paid occupation and an elite career choice that involves lots of underwater adventure and travelling. Underwater welders are also called offshore welders, and they are required to have both welding and commercial diving skills. 

4.1 Education and Qualifications 

There is no age bar to apply for this occupation; 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.Underwater welding

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 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, which includes underwater cutting, fitting, rigging, underwater photography, inspection, and non-destructive testing and drafting. The welders should be highly qualified and competent for project managing posts. 

4.3 Salaries of underwater welders

The pay of an underwater welder is judged based on the project undertaken. This includes many aspects like the length of the project, dive methods and welding techniques employed, and the hazard levels. Qualifications and posts are other parameters that govern their salaries. Underwater welding

According to the data collected from commercial divers and global statistics, an underwater welder earns $53,990 annually or $25.96 per hour. Top 10% diver welders who have high qualifications and experience can make up to $83,730, while the bottom 10%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 being $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 American welding society- U.S. Bureau of Labor Statistics.

 

So in this article, we portrayed everything about Underwater welding starting from its description, health hazards, and job requirements of underwater welders. I hope you found it informative and enjoyed reading it. 

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