Underwater Welding:-

Underwater welding is one of the most dangerous occupations in the world. Underwater, the odds are stacked against you. The pressure threatens to crush the body. Clouds of bubbles making any task difficult to perform by blocking visuals.Underwater welders are responsible for repairing pipelines, offshore oil drilling rigs, ships, dams, locks, sub-sea habitats and nuclear power facilities, to name a few.

Underwater welding is the process of welding at elevated pressures, normally underwater. Underwater welding can either take place wet in the water itself or dry inside a specially constructed positive pressure enclosure and hence a dry environment.So,it can be classified into two categories:

  1. Wet Welding
  2. Dry Welding

Wet Welding:

Wet underwater welding directly exposes the diver and electrode to the water and surrounding elements.Divers usually use around 300–400 amps of direct current to power their electrode, and they weld using varied forms of arc welding.This practice commonly uses a variation of shielded metal arc welding, employing a waterproof electrode.

Wet welding with a stick electrode is done with similar equipment to that used for dry welding, but the electrode holders are designed for water cooling and are more heavily insulated. They will overheat if used out of the water.The electric arc heats the workpiece and the welding rod, and the molten metal is transferred through the gas bubble around the arc. 

The hazards of underwater welding include the risk of electric shock to the welder. To prevent this, the welding equipment must be adaptable to a marine environment, properly insulated and the welding current must be controlled.

Dry Welding / Hyperbaric Welding:

Another method of welding underwater is hyperbaric welding or dry welding. Hyperbaric welding is the process by which a chamber is sealed around the structure that is to be welded. It is then filled with a gas (typically mixture of helium and oxygen, or argon), which then forces the water outside of the hyperbaric sphere.

In most cases, and most ideally, a dry chamber system is used. Temporary hyperbaric chambers are used to prevent water from entering the work area. The chambers house up to three welders at a time.
Underwater welding is one of the most difficult jobs on the planet and in the water. Though with advancing technologies in robotic capabilities, advancements are being made to protect underwater welders. Despite what the future may hold, today underwater welders help maintain the most integral components of many industries around the world.

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