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Seminar
On
Underwater welding
Submitted to: submitted by:
Department of Mechanical MOHAN BIHARI
engineering 12EEJME029 1
UNDERWATER WELDING
Mohan Bihari
12eejme029
m4ubihari@gmail.com
SEMINAR ON
2
• First under water welding by British Admiralty
– Dockyard
• In 1946, special waterproof electrodes were
developed in Hol...
INTRODUCTION TO
UNDERWATER WELDING
4
We cant lift ship and then repair it. Hence comes the use of underwater
welding
5
•Wet welding •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 ...
Dry welding can be of two types
•Large habitat
•Mini habitat
Mini habitat for underwater
welding.
8
Large habitat for unde...
9
Large habitat underwater welding
•Welder /diver safety
•Good weld quality
•Surface monitoring
10
• Higher cost of process, training, etc
• Large quantity o...
• Simply means that job is
performed directly in the water
• It involves using special rod and
is similar to the process i...
12
• Cheapest
• Fastest
• Tensile strength is high
• Ease of access the weld spot
• No waste of time in constructing habitat
...
• Rapid quenching decreases impact strength,
Ductility.
• Hydrogen embrittlement.
• Poor visibility in water.
• Higher ene...
15
16
 Offshore construction for tapping sea
resources.
 Temporary repair work caused by ship’s
collisions or unexpected ac...
• Hydrogen and oxygen are dissociated
from the water and will travel separately
as bubbles
• Oxygen cutting is about 60 pe...
• There is a risk to the welder/diver of electric
shock.
• There is a risk that defects may remain
undetected
• The other ...
• Start cutting at the highest point and work
downward
• By withdrawing the electrode every few
seconds to allow water to ...
• Precautions include achieving adequate
electrical insulation of the welding
equipment
• Areas and voids must be vented o...
• Development of alternative welding methods
like friction welding, explosive welding, and
stud welding.
• Present trend i...
22
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Under water welding ppt

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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Under water welding ppt

  1. 1. Seminar On Underwater welding Submitted to: submitted by: Department of Mechanical MOHAN BIHARI engineering 12EEJME029 1
  2. 2. UNDERWATER WELDING Mohan Bihari 12eejme029 m4ubihari@gmail.com SEMINAR ON 2
  3. 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. 3
  4. 4. INTRODUCTION TO UNDERWATER WELDING 4
  5. 5. We cant lift ship and then repair it. Hence comes the use of underwater welding 5
  6. 6. •Wet welding •Dry welding 6
  7. 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. 7
  8. 8. Dry welding can be of two types •Large habitat •Mini habitat Mini habitat for underwater welding. 8 Large habitat for underwater welding
  9. 9. 9 Large habitat underwater welding
  10. 10. •Welder /diver safety •Good weld quality •Surface monitoring 10 • 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. 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 11
  12. 12. 12
  13. 13. • Cheapest • Fastest • Tensile strength is high • Ease of access the weld spot • No waste of time in constructing habitat 13
  14. 14. • Rapid quenching decreases impact strength, Ductility. • Hydrogen embrittlement. • Poor visibility in water. • Higher energy density of hydrogen, higher efficiency. 14
  15. 15. 15
  16. 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. 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. 17
  18. 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 18
  19. 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. 19
  20. 20. • Precautions include achieving adequate electrical insulation of the welding equipment • Areas and voids must be vented or made inert 20
  21. 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. 21
  22. 22. 22

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