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Underwater welding

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Shobhit Ishan
Shobhit Ishan

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.

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SEMINAR ON UNDERWATER WELDING TECHNOLOGY ,ART , COURAGE 1 SHOBHIT ISHAN 474/09
• First under water welding by British Admiralty – Dockyard • In 1946, special waterproof electrodes were developed in Holland by ‘Van der Willingen’ 2
INTRODUCTION TO UNDERWATER WELDING 3
We cant lift ship and then repair it. Hence comes the use of underwater welding 4
•Wet welding 5 •Dry welding
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. 6
Dry welding can be of two types •Large habitat •Mini habitat 7 Mini habitat for underwater welding.
Source: north stream Large habitat for 8 underwater welding
9 Large habitat underwater welding
•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
• 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 12
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• 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 15
Chemical composition 16
Porosity-troubleshooted by including Calcium carbonate 17
•Microstructure •Mechanical properties 18
• Effect of alloying elements on weld metal microstructure and properties • Managanese • Boron and titanium • Rare earth metals 19
• Cheapest • Fastest • Tensile strength is high • Ease of access the weld spot • No waste of time in constructing habitat 20
• Rapid quenching decreases impact strength, Ductility. • Hydrogen embrittlement. • Poor visibility in water. • Higher energy density of hydrogen, higher efficiency. 21
• 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. 22
• Underwater Oxygen-Arc Welding Torches.- Collet or grip Oxygen valve Flash arrester • Waterproofing Surface Electrodes. Epoxy 152 Lee lac 30-l2093 Polyurethane 23
Figure showing schematic diagram for underwater welding or cutting 24
• 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. 25
• 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 26
• 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. 27
• Precautions include achieving adequate electrical insulation of the welding equipment • Areas and voids must be vented or made inert 28
• 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. 29
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Underwater welding

  • 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’ 2
  • 4. We cant lift ship and then repair it. Hence comes the use of underwater welding 4
  • 5. •Wet welding 5 •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. 6
  • 7. Dry welding can be of two types •Large habitat •Mini habitat 7 Mini habitat for underwater welding.
  • 8. Source: north stream Large habitat for 8 underwater welding
  • 10. •Welder /diver safety •Good weld quality •Surface monitoring 10
  • 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 11
  • 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 12
  • 13. 13
  • 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 15
  • 17. Porosity-troubleshooted by including Calcium carbonate 17
  • 19. • Effect of alloying elements on weld metal microstructure and properties • Managanese • Boron and titanium • Rare earth metals 19
  • 20. • Cheapest • Fastest • Tensile strength is high • Ease of access the weld spot • No waste of time in constructing habitat 20
  • 21. • Rapid quenching decreases impact strength, Ductility. • Hydrogen embrittlement. • Poor visibility in water. • Higher energy density of hydrogen, higher efficiency. 21
  • 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. 22
  • 23. • Underwater Oxygen-Arc Welding Torches.- Collet or grip Oxygen valve Flash arrester • Waterproofing Surface Electrodes. Epoxy 152 Lee lac 30-l2093 Polyurethane 23
  • 24. Figure showing schematic diagram for underwater welding or cutting 24
  • 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. 25
  • 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 26
  • 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. 27
  • 28. • Precautions include achieving adequate electrical insulation of the welding equipment • Areas and voids must be vented or made inert 28
  • 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. 29
  • 30. 30