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Under water welding

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About Under water Welding In and Out fully has been Discussed in the PPT by the Students

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Under water welding

  1. 1. UNDERWATER WELDING PAPER PRESENTED BY SUDERSON.B SHANKAR.P Guided By , M.Maniyarasan& M.Soundarrajan, AP/MECH
  2. 2. UNDERWATER WELDING
  3. 3. NEED FOR UNDERWATER WELDING  To repair the cracks in ships ,bridge and submarine.  For quick process in under water welding.  To construction of pipe line in under sea.  To weld any cracks in oil pipe line.
  4. 4. Requirement of underwater welding Power supply requirements 400 Amp or larger. DC generators, motor generators and rectifiers are acceptable power supplies.  Power converters.  Welding Generator, Pre-Setup.  Diesel Driven Welding Generator Amperage and Voltage settings.  Gas Manifolds.
  5. 5.  Underwater Oxygen-Arc Welding Torches. 1.Collet or grip 2.Oxygen valve 3.Flash arrester  Waterproofing Surface Electrodes. 1.Epoxy 152 2.Lee lac 30-l2093 3.Polyurethane
  6. 6. Difference between normal welding and underwater welding Under water welding 1 . Underwater Welding & Burning: 6,500 – 10,000° F Under the Sea. 2. Under the water, metal sounds different. It’s high pitched but muffled like a siren entering a tunnel. It dissipates quickly out into the waves .  Ground welding 1. In the electric arc, the temperature is very high of the order of 6,000-8,000 °C for the GTAW, GMAW, FCAW and SAW processes. 2. It up to 10,000 20,000 °C for the PAW process and well above the boiling point of the base and filler materials
  7. 7. Sea driver equipment Fully insulated electrode holder. Oxygen cylinder. HOFR cable for power supply (double insulated cable). Dry suit, helmet and head light. Electrode core wire with heavy coating.
  8. 8. Classification of under water welding Wet welding:  In this process it is directly exposed to the environment.  And special water proof electrode is used in this type of welding. Dry welding:  In this process it is seal by closed chamber filled with gas to elevated pressure.  Gas tungsten arc welding is most commonly used.
  9. 9. Wet welding It is carried out directly at ambient water pressure with the welder/driver in water By using water proof stick electrode and without any physical barrier between water and welding Mostly used Gas metal arc welding.
  10. 10. Wet welding process
  11. 11. Advantage of wet welding Minimal amount of equipment is needed. Operating speed is high. No seal chamber is required.
  12. 12. Disadvantage of wet welding Repaid quenching of the weld metal by surrounding water. Decreases impact strength and losses. Hydrogen embattlement causes cracks. Poor visibility in water. Electric shock will occurred.
  13. 13. Application of wet welding It is key technology for repairing marine structure . Welding is directly performed under water is directly exposed to the wet environment. Increased freedom movement makes more effective , efficient and economical. Supply is connected to the welder / driver via cables or hoses.
  14. 14. 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 0.5 bar of Oxygen) at the prevailing pressure.
  15. 15. Hyperbaric welding process
  16. 16. Advantages of Dry welding More safety then wet welding. Good Quality weld. Surface monitoring. Non destructive testing possible.
  17. 17. Disadvantages of Dry welding Higher cost of process, training, etc. Large quantity of costly and complex equipment. More deep, more energy requirement. It should be weld only reachable place.
  18. 18. Application of underwater dry welding To Maintain the oil pipe lines in under water. Construction of pipe line under sea.
  19. 19. Advance in under water welding LASER BEAM WELDING
  20. 20. Risk involved in under water welding Electric shock explosion. Risk is to the life of the welder. High pressure is formed. Shark attack under deep sea welding.
  21. 21. Dangerous and difficulties 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. 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
  22. 22. Future scope and developments 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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