• WATER-------------HYDROGEN +
• Dissolve in weld pool
• Solubility decrases and then comes out -
• Oxygen as solid , liquid inclusions or
• Hydrogen combines with oxygen forming
• Effect of alloying elements on weld metal
microstructure and properties
• Boron and titanium
• Rare earth metals
• Tensile strength is high
• Ease of access the weld spot
• No waste of time in constructing habitat
• Rapid quenching decreases impact
• Hydrogen embrittlement.
• Poor visibility in water.
• Higher energy density of
hydrogen, higher efficiency.
• Power supply requrements-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.
Figure showing schematic diagram for
underwater welding or cutting
• Hydrogen and oxygen are dissociated
from the water and will travel separately
• Oxygen cutting is about 60 percent
• 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
• There is a risk that defects may remain
• 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
• Start cutting at the highest point and work
• 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.
• Precautions include achieving adequate
electrical insulation of the welding
• Areas and voids must be vented or made
• Development of alternative welding methods
like friction welding, explosive welding, and
• 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.