Presented by MAYUR M. LANDGE(Vth Sem. Mech. Engg.)

Guided byProf: P. H. SAHARE

Introduction:• Underwater welding is an important tool for underwater

fabrication works.

• In 1946, special waterproof electrodes were developed in

Holland by ‘Vander Willingen'’.

• In recent years the number of offshore structures including oil

drilling rigs, pipelines, platforms are being installed

significantly.• Invented by Konstantin Khrenov in1930.

Classification:

• Under water welding can be classified as :

1) Wet welding

2) Dry welding

Classification:

1. Wet welding• Direct contact with water. • Shielding gases.• Quick water quench.• All equipments insulated.

• Power supply by cables.

Fig. Wet welding process

Fig. Wet welding

2. Dry welding • sealed chamber filled with gases.• Favorable condition for welder.• High accuracy welding.• A chamber is created near the area to be welded and the

welder does the job by staying inside the chamber.• It produces high quality weld joints .• The gas-tungsten arc welding process is used mostly for pipe

works• Gas metal arc welding is the best process for this welding.

Fig. Mini-Habitat welding

Equipments:

• Tong Test Ammeter.• Power converters. • Safety knife Switches.• Power Supply Requirements.• All equipments is insulated.

Fig. Tong Test Ammeter

Advantages:1.Wet welding:• Low cost.• Enclosure not needed.• Less time.• No enclosures so no time is lost for

building

2.Dry welding :• High accuracy welding.• Unskilled welder.• Driver safety.• Non destructive testing Fig. Wet welding

Disadvantage:

1.Wet welding:• Unstable platform.• Poor visibility.• Hydrogen embrittlement.• Cleaning the surface.2.Dry welding:• Time consuming is more.• Costlier.• Complex process.• Cost Is High.

Fig. Cleaning the surface.

Applications:

• Repairing of pipelines due to cyclones. • Repairing of ships due to collisions.• Oil drilling platform.• Submarines use in war.• Dams and bridges c• New construction & installation structures.• Subsea pipelines, & harbor facilities.• maintenance and repair these includes repair of damage caused

by corrosion, fatigue • Repairing holes in ship’s hulls or collision damage to harbor

facilities.• Construction.

Risk Involved:

• Danger of an Electric Shock.• Possibility of an Explosion.• Decompression Sick. • Hydrogen and oxygen bubbles are explosive.• Danger of drowning due to failure of equipments.• Danger of marine animals.

Development:• Automation in THOR – 1 (TIG Hyperbaric Orbital Robot)• A series of spot welds.• Inspection done by ROV machine. • Under water welding institutions.

fig. ROV machine

Reference:

www.twi.com

www.aws.com

Production Technology- O.P.Khanna

www.howstuffworks.com

THANK YOU…….