NEED FOR UNDERWATER WELDING
To repair the cracks in ships ,bridge and
For quick process in under water welding.
To construction of pipe line in under sea.
To weld any cracks in oil pipe line.
Requirement of underwater
Power supply requirements 400 Amp or
larger. DC generators, motor generators and
rectifiers are acceptable power supplies.
Welding Generator, Pre-Setup.
Diesel Driven Welding Generator Amperage
and Voltage settings.
Difference between normal
welding and underwater welding
Under water welding
1 . Underwater Welding & Burning: 6,500 – 10,000° F Under
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 .
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
Sea driver equipment
Fully insulated electrode holder.
HOFR cable for power supply
(double insulated cable).
Dry suit, helmet and head light.
Electrode core wire with heavy
Classification of under water
In this process it is directly exposed to the
And special water proof electrode is used
in this type of welding.
In this process it is seal by closed chamber
filled with gas to elevated pressure.
Gas tungsten arc welding is most
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.
Advantage of wet welding
Minimal amount of equipment is needed.
Operating speed is high.
No seal chamber is required.
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.
Application of wet welding
It is key technology for repairing marine
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.
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
Advantages of Dry welding
More safety then wet welding.
Good Quality weld.
Non destructive testing possible.
Disadvantages of Dry welding
Higher cost of process, training, etc.
Large quantity of costly and complex
More deep, more energy requirement.
It should be weld only reachable place.
Application of underwater dry welding
To Maintain the oil pipe lines in under water.
Construction of pipe line under sea.
Advance in under water welding
LASER BEAM WELDING
Risk involved in under water
Electric shock explosion.
Risk is to the life of the welder.
High pressure is formed.
Shark attack under deep sea welding.
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
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.