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

1. UNDERWATER
WELDING
PAPER PRESENTED BY
SUDERSON.B
SHANKAR.P
Guided By ,
M.Maniyarasan&
M.Soundarrajan,
AP/MECH

2. UNDERWATER WELDING

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. 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.  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. 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. 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. 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. 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. Wet welding process

11. Advantage of wet welding
Minimal amount of equipment is needed.
Operating speed is high.
No seal chamber is required.

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. 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. 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. Hyperbaric welding process

16. Advantages of Dry welding
More safety then wet welding.
Good Quality weld.
Surface monitoring.
Non destructive testing possible.

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. Application of underwater dry welding
To Maintain the oil pipe lines in under water.
Construction of pipe line under sea.

19. Advance in under water welding
LASER BEAM WELDING

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. 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. 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.