Underwater welding includes a lot of different processes that join metals on offshore oil platforms, pipelines & ships .It is the process of welding under water using various techniques under various conditions.....etc.!!!
2) Precautions must be taken to avoid the build-up of pockets of gas, which are potentially explosive . 3) Precautions include the provision of an emergency air or gas supply, stand-by divers, and decompression chambers to avoid nitrogen
Under water welding
PRESENTED BY –
REG NO. : 149me12031
GUIDED BY –
what is an Under
welding includes a
lot of different
processes that join
metals on offshore
pipelines & ships
PRINCIPLE OF OPERATION
•The welding circuit must include a positive type of switch, usually
a knife switch operated on the surface and commanded by the
welder and is used for safety reasons.
•For wet welding AC is not used on account of electrical safety
and difficulty in maintaining an arc underwater
In wet welding the base metal and
the arc are surrounded entirely by
water. In wet welding MMA (manual
metal arc welding) is used.
Welding in the wet environment
The increased freedom of movement
makes wet welding the most effective,
efficient and economical method.
Welding power supply is located on
the surface with connection to the
diver/welder via cables
• cheapest and fastest method
• tensile strength is high
• easy of access the weld spot
• no waste of time
• Decreases impact strength and
• chances of cracking
• Poor visibility in water
• Lack of experienced worker
RISK INVOLVED & SAFETY
Electric shock Explosion.
Hydrogen and Oxygen are produced during
risk is to the life or health of the welder.
Inspection of welds.
• Offshore construction for tapping sea resources,
Temporary repair work caused by ship’s
collisions or unexpected accidents.
•Repair and maintenance of ships, Construction
of large ships beyond the capacity of existing.
At present, underwater welding becomes more
sophisticated and can be done deeper. It has been used
to weld pipes at depths of 200 ft (61 m) and has produced
an X-ray quality welds meeting the requirements of
Standards. Offshore oil explorations have increased the
interest in underwater welding.
Wet Underwater Welding method uses a waterproof
welding electrodes. The power of the arc generates a
bubble of a mixture of gasses which lets metal melting
and joining occur more or less normal.