Underwater Welding

1. Seminar
On
Underwater welding
Submitted to: submitted by:
Department of Mechanical Rohit Kawlani
engineering 19EUCME053 1

2. • 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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3. INTRODUCTION TO
UNDERWATER WELDING
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4. We cant lift ship and then repair it. Hence comes the use of underwater
welding
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5. •Wet welding •Dry welding
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6. 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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7. 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

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Large habitat underwater welding

9. •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

10. • 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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12. • Cheapest
• Fastest
• Tensile strength is high
• Ease of access the weld spot
• No waste of time in constructing habitat
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13. • Rapid quenching decreases impact strength,
Ductility.
• Hydrogen embrittlement.
• Poor visibility in water.
• Higher energy density of hydrogen, higher
efficiency.
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 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.

16. • 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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17. • 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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18. • 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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19. • Precautions include achieving adequate
electrical insulation of the welding
equipment
• Areas and voids must be vented or made
inert
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20. • 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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