The document discusses underwater welding technology. It describes how underwater welding was first developed by the British Admiralty and then special waterproof electrodes were created. It discusses the different types of underwater welding including wet welding, dry welding using hyperbaric chambers, and different habitat sizes. It outlines the challenges of underwater welding including costs and equipment needs. It also discusses the welding processes, necessary equipment, safety considerations, and developing automation trends in the field.

1. SEMINAR ON
UNDERWATER WELDING
TECHNOLOGY ,ART , COURAGE
1 SHOBHIT ISHAN
474/09

2. • First under water welding by British
Admiralty – Dockyard
• In 1946, special waterproof electrodes were
developed in Holland by ‘Van der
Willingen’
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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
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•Dry welding

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
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Mini habitat for underwater welding.

8. Source: north stream
Large habitat for 8
underwater welding

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Large habitat underwater welding

10. •Welder /diver safety
•Good weld quality
•Surface monitoring
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11. • 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
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12. • 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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14. ‹#›

15. • WATER-------------HYDROGEN +
OXYGEN
• Dissolve in weld pool
• Solubility decrases and then comes out -
 porosity
• Oxygen as solid , liquid inclusions or
gases
• Hydrogen combines with oxygen forming
vapour
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16. Chemical composition
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17. Porosity-troubleshooted by including Calcium
carbonate
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18. •Microstructure
•Mechanical
properties
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19. • Effect of alloying elements on weld metal
microstructure and properties
• Managanese
• Boron and titanium
• Rare earth metals
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20. • Cheapest
• Fastest
• Tensile strength is high
• Ease of access the weld spot
• No waste of time in constructing habitat
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21. • Rapid quenching decreases impact
strength, Ductility.
• Hydrogen embrittlement.
• Poor visibility in water.
• Higher energy density of hydrogen,
higher efficiency.
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22. • Power supply requrements-400 amp or larger.
DC generators, motor generators and rectifiers
are acceptable power supplies
• Power converters.
• Welding Generator, Pre-Setup
• Polarity.
• Diesel Driven Welding Generator Amperage
and Voltage settings.
• Gas Manifolds.
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23. • Underwater Oxygen-Arc Welding
Torches.-
Collet or grip
Oxygen valve
Flash arrester
• Waterproofing Surface Electrodes.
Epoxy 152
Lee lac 30-l2093
Polyurethane
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24. Figure showing schematic diagram for
underwater welding or cutting
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25. • 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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26. • 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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27. • 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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28. • Precautions include achieving adequate
electrical insulation of the welding
equipment
• Areas and voids must be vented or made
inert
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29. • 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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