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1. UNDERWATER WELDING
Presented by,
Lara fedrick.S, Vikas.P.S,
Indra Ganesan College Of Engineering,
Trichy-12.
1

2. Introduction
 The fact that electric arc could operate was known for over
a 100 years
 The first ever underwater welding was carried out by
British Admiralty – Dockyard for sealing leaking ship
rivets below the water line.
 In 1946, special waterproof electrodes were developed in
Holland by ‘Van der Willingen’.
 Any repair method under the sea will require the use of
underwater welding.
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3. WELDING
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4. What is welding
 Welding is a process for joining two similar or dissimilar metals
by fusion.
 It joins different materials / alloys with or without the application
of pressure and with or without the use of filler metal.
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5. Necessity of underwater welding
 To provide a permanent joining between two metals inside
present under the water
 High pressure pipe lines cannot be joint using temporary fasteners
such as bolts and nuts. Hence welding is compulsory in high
pressure pipe linings.
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6. Principle
 The work to be welded is connected to one side of an electric circuit
by means of a cable. A flux-coated electrode is attached to a holder,
also connected via cable, both being attached to a power source.
 When the electrode makes contact with the work, an electrical
contact is made. The electric current jumps the gap and create a
spark (arc), which melts the base metal and the covering of the
electrode forming a common weld puddle.
 Complete insulation of the cable and hoses is essential in case to
prevent the chance for electric shock.
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7. Arrangement of
underwater welding
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8. Schematic diagram of
Underwater welding
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9. Requirements of
Underwater welding
 Power converters.
 Welding Generator, Pre-Setup
 Polarity.
 Gas Manifolds.
 Welding Generator Amperage and Voltage settings.
Underwater Oxygen-Arc Welding Torches
 Collet or grip
 Oxygen valve
 Flash arrester
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10. Classification
Wet welding Dry welding
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11. Wet welding
 Wet Welding indicates that welding is performed underwater,
directly exposed to the wet environment. It similar used as
ordinary air welding
 In this process we using special electrodes which is made of
copper coated , carbon/graphite electrodes.
 Welding power supply is located on the surface with connection
to the diver/welder via cables and hoses
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12. power Supply used : DC
Polarity : -ve polarity
 The power source should be a direct current machine rated at
300 or 400 Amps
 We must connect the polarity as a negative supply. If we connect dc supply
as a positive polarity electrolysis will occur and it causes rapid deterioration
on metallic components. 12

13. Figures of wet welding
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14. Advantages
 It is economical and fastest
method
 It has a high tensile strength
 Ease to access the weld spot
 Less time consumption for
welding
Disadvantages
 Poor visibility in water
during process
 It reduce the ductility and
impact strength of welded
material.
 It increase the hydrogen
embrittlement
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15. Dry welding
 In dry welding dry environment is made possible by
encompassing the area to be welded.
 The chamber is placed near the structure where to be weld.
 The chamber is filled with a gas (commonly helium containing
0.5 bar of oxygen) at the prevailing pressure
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16. There are two types of dry welding:
Large habitat
Mini habitat 16

17. Large habitat Mini habitat
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18. Advantages
 Welder/diver is safety
 Good quality weld
 Surface monitoring
 Non destructive testing
Disadvantages
 Highly cost equipment.
 Skilled labour required.
 We can’t weld unreachable
spot
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19. Developments of
underwater welding
 Wet welding has been used as an underwater welding technique
for a long time and is still being used.
 With recent acceleration in the construction of offshore structures
underwater welding has assumed increased importance.
 With recent acceleration in the construction of offshore structures
underwater welding has assumed increased importance.
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20. Risks & precaution
 Risk of electric shock so achieving electrical insulation of
electrical welding equipment's
 Hydrogen and oxygen are produced by the arc in wet welding are
potentially explosion so precaution must be taken to avoid the
build up of pockets of gas
 The life of the welder will be risk from nitrogen introduced into
the blood stream, precaution include the provision of an
emergency air gas supply 20

21. Application
 Offshore construction for tapping sea source
 Temporary repair work caused by ship collision, unexpected
accident
 Maintenance of ships
 Pipelines and Tunnels
 Oil refineries
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22. CONCLUSION
 Thus underwater welding facilities creating
permnant joint in a deep sea in effective way though
it may affect underwater welding habitats further
modification of developments in process can
improve effectiveness of underwater welding.
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23. References
 1) D. J Keats, Manual on Wet Welding.
 2) Annon, Recent advances in dry underwater pipeline welding,
Welding Engineer, 1974.
 3) Lythall, Gibson, Dry Hyperbaric underwater welding, Welding
Institute.
 4) W.Lucas, International conference on computer technology in
welding.
 5) Stepath M. D, Underwater welding and cutting yields slowly to
research, Welding Engineer, April 1973.
 6) Silva, Hazlett, Underwater welding with iron – powder
electrodes, Welding Journal, 1971
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24. Thank you
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