Underwater welding is needed to repair cracks in ships, bridges, and submarines or construct underwater pipelines. It can be done through wet welding, where the welder works directly in water, or dry welding within a pressurized chamber. Wet welding uses specialized electrodes and equipment but has more freedom of movement, while dry welding has better quality control but is more complex and expensive. Hazards of underwater welding include electric shock, gas explosions, and pressure injuries. Automation is increasingly used to reduce risks to divers.

1. UNDER-WATER
WELDING
Prepared by
Prof. P.A.Nadgouda
Assistant Professor
DYPCET

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.