Why is Underwater Welding so Dangerous

Why is underwater welding so dangerous

Underwater welding involves a high degree of technical complexity. It is basically applied in ship building and maintenance, waterway structures, submarines, subsea pipelines, offshore oil rigs and nuclear reactors etc. High quality standards are required for underwater welding systems and personnel. Underwater welding profession is attracting much more than other professions since it is more challenging and highly paid. In view of this fact, an attempt has been made to briefly discuss its mechanism, challenges, risks and recent advancements.

Introduction:

Welding is different from brazing or soldering in which the base metal is not melted. During welding two or more parts are fused by means of heat, pressure or both and a join is formed after cooling. In fact welding is joining of two objects together using heat and filler material. The filler is heated to melt and pool between the two parts to form a strong joint/weld.

Thus welding is a fabrication process performed at both inland and offland. Arc welding with consumable metal electrodes was introduced by Nikolay Slavyanov in 1888, whereas Soviet Engineer Konstantin Khrenov invented underwater welding in 1932 to weld fully or partially submerged marine structures. It involves welding at high pressures and is also known as hyperbaric welding. In 1936, crews performed underwater welding to lift an enormous ship called Boris out of the Black Sea and in 1940 an underwater welding program was led by Cyril Jensen in the US Navy to repair bridges, dams, pipelines, oil rigs and other marine infrastructure.

Why underwater welding is needed:

Since it is not possible to take out the structure from the water and perform its maintenance, it becomes essential to adopt underwater welding for the repair and maintenance of such structures. Underwater welding is required for underwater construction and repair of ships and pipelines. Further due to frequent storms and unexpected collisions, the parts of offshore structures are damaged, underwater welding is required for the repair and maintenance of such offshore structures.

Underwater welding processes are also being applied almost in all manufacturing industries as well as for fabrication of structures. Presently important applications of underwater welding are – (i) offshore construction for taping sea nodules (ii) temporary repair work caused by ship’s collisions or unexpected accidents and (iii) construction of large ships beyond the capacity of existing docks. Further underwater welding is playing key role in the instalment of large number of offshore structures including oil drilling rigs, pipelines and platforms.

Why is underwater welding so dangerous?

Underwater welding involves tasks of performing welding below the surface of water. But there are many risks associated with the underwater welding, such as combination of high-pressure environments, electrical risks, water and electricity interaction, high pressure and depth of water, problem of visibility etc.

• High electrical risks: If we think of the risks of underwater welding, the first danger comes to mind is the risk of electrical shock. The electrical currents used in the underwater welding can easily transmitted through the welder’s electrode. As water is a good conductor of electricity, increases the risks of electrical shock significantly. Welders must understand the risks and use specialized equipment to minimize the electrical risks.
• High pressure and depth of water: Often the underwater welding is done at great depths of water for the repair and maintenance of structures. As the depth increases, the chance of atmospheric pressure increases which can affect the welder’s body and performing the tasks of welding. There is a great risks of decompression sickness as being exposed to high-pressure environments.
• Low visibility: Visibility is another great challenge of working underwater welding. Visibility is limited by murky water, and the welder is often required to maneuver in tight, confined spaces while wearing heavy protective gear. Low visibility can lead the welder of making mistakes which cause severe accidents or damaging of equipment.
• Risks of drowning: As underwater welders work hundreds of feet beneath the surface and face pressure changes, they may suffer from decompression sickness and arterial gas embolism. It may lead to the welder being struck underwater for prolonged periods, increasing the risk of suffocation or drowning.
• Cold water and Hypothermia: Underwater welding is basically applied in ship building and maintenance, waterway structures, submarines, subsea pipelines etc. These types of underwater welding are often done in cold or freezing temperature of water. Working in cold water heightens the risks of hypothermia. Hypothermia can impair a welder’s cognitive and physical abilities, making it harder to perform tasks and respond to emergencies.

Underwater welding process:

Underwater welding process is classified as (i) wet underwater welding (ii) dry underwater welding. Further wet underwater welding classified into three types and dry underwater welding into six types as shown below. In wet underwater welding process, the welding is performed freely under water in wet environment, whereas in dry underwater welding a dry chamber is created and welding is performed inside the dry chamber in dry environment.

Underwater Welding

Mechanism of underwater welding:

In order to understand the mechanism of underwater welding one has to understand the process of evolution of oxygen, bubbling phenomenon, cooling of weld, flow of electric current and control mechanism etc.

Science and technology behind welding:

Welding continued to evolve to its modern day form by involving the scientific principles, chemistry, mechanics, electronics and materials. It is essential to understand the materials and their properties. Generally the parent material is heated to a high temperature, it melts and combines with other materials forming a strong weld joint after cooling.

Some methods of welding make use of heat to melt two pieces of metal together by adding a filler metal into the joint which acts as a binding agent, some rely on pressure which binds metals together while others make use of both heat and pressure. Welding has now advanced significantly to become more accurate, fast and effective. The methods of welding are constantly being developed wit new research in the nuclear, space, transportation and ship building industries.

Conclusion:

As underwater welders work hundreds of feet beneath the surface and face pressure changes, they may suffer from decompression sickness and arterial gas embolism. Though wet welding usually costs less than dry welding, but it is more dangerous. Wet welders perform underwater welds the same way they would on dry land. Utilization of welding processes is booming to its full potential day by day with increasing marine and offshore applications reducing the risks of underwater welding. Technologies have come up with a solution of advanced welding process which can be suitable underwater for simple, quick and high quality weld.

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