Hyperbaric welding is the process in which a chamber is sealed around the structure to be welded and is filled with a gas ( He and Oxygen) at the prevailing pressure.
3. • First under water welding by British Admiralty
– Dockyard
• In 1946, special waterproof electrodes were
developed in Holland by ‘Van der Willingen’
• 1970s: Whitey Grubbs and Dale Anderson of
Chicago Bridge & Iron (CB&I) qualified an
underwater wet welding procedure to
American Welding Society (AWS) standards.
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7. Hyperbaric welding is the process in which
a chamber is sealed around the structure to
be welded and is filled with a gas ( He and
Oxygen) at the prevailing pressure.
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8. Dry welding can be of two types
•Large habitat
•Mini habitat
Mini habitat for underwater
welding.
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Large habitat for underwater welding
10. •Welder /diver safety
•Good weld quality
•Surface monitoring
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• Higher cost of process, training, etc
• Large quantity of costly and complex equipments
• More deep, more energy requirement.
• Cant weld if weld spot is at unreachable place
11. • Simply means that job is
performed directly in the water
• It involves using special rod and
is similar to the process in
ordinary air welding
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16. 16
Offshore construction for tapping sea
resources.
Temporary repair work caused by ship’s
collisions or unexpected accidents.
Salvaging vessels sunk in the sea.
Repair and maintenance of ships.
Construction of large ships beyond the
capacity of existing docks.
Repair and maintenance of underwater
pipelines.
17. • Hydrogen and oxygen are dissociated
from the water and will travel separately
as bubbles
• Oxygen cutting is about 60 percent
efficient
• Above river beds, especially in mud,
because trapped methane gas in the
proper concentrations can explode.
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18. • There is a risk to the welder/diver of electric
shock.
• There is a risk that defects may remain
undetected
• The other main area of risk is to the life or
health of the welder/diver from nitrogen
introduced into the blood steam during exposure
to air at increased pressure
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19. • Start cutting at the highest point and work
downward
• By withdrawing the electrode every few
seconds to allow water to enter the cut
• Gases may be vented to the surface with a vent
tube (flexible hose) secured in place from the
high point where gases would collect to a
position above the waterline.
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20. • Precautions include achieving adequate
electrical insulation of the welding
equipment
• Areas and voids must be vented or made
inert
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21. • Development of alternative welding methods
like friction welding, explosive welding, and
stud welding.
• Present trend is towards automation. THOR – 1
(TIG Hyperbaric Orbital Robot) is developed
where diver performs pipefitting, installs the
track and orbital head on the pipe and the rest
process is automated.
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