under water welding

UNDERWATER WELDING

PRESENTED BY –

NANDISH

REG NO. : 149me12031

GUIDED BY – VIRUPAKSHAPPA.Y.K

B.E[MECH],MISTE

CONTENTS

• Importance Of Underwater Welding

• Principle Of Operation

• Classification

• Wet Underwater Welding

• Advantages & Disadvantages

• Risk Involved & Safety

• Conclusion

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what is an Under water welding???

Underwater welding includes a lot of different processes that join metals on offshore oil platforms, pipelines & ships etc.

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PRINCIPLE OF OPERATION

_Power Supply

- +

work

Knife switch

electrode

Waterproof Electrode

Holder

• 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

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CLASSIFICATION

1.Welding in-the-wet environment 2.Welding in-the-dry environment

Dry welding Wet welding

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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

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ADVANTAGES

• cheapest and fastest method

• tensile strength is high

• easy of access the weld spot

• no waste of time

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DIS-ADVANTAGES

• Decreases impact strength and

looses ductility

• chances of cracking

• Poor visibility in water

• Lack of experienced worker

RISK INVOLVED & SAFETY

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Electric shock Explosion.

Hydrogen and Oxygen are produced during welding.

risk is to the life or health of the welder.

Inspection of welds.

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APPLICATIONS

• 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.

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CONCLUSION

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.

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THANK YOU