Underwater welding

UNDERWATER

WELDING

S.C. MOI

GUIDED BY

INTRODUCTION PRINCIPLE CLASSIFICATION WET WELDING DRY WELDING APPLICATION RISK INVOLVED

SLIDE PLAN

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.

INTRODUCTION

Underwater welding is the type of welding which takes place under water. And this is an important tool for underwater fabrication works.

UNDERWATER WELDING

The work to be welded is connected to one side of an electric

circuit, via means of a cable. A flux-coated electrode is attached to a holder, also connected via a 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 created spark (arc), which melts the base metal and the covering of the electrode forming a common weld puddle.

Complete insulation of the cable and horses is essential in case to prevent the chance for electric shock.

Manual metal arc welding is commonly used in this welding.

PRINCIPLE

Underwater welding can be classified as:

1.WET WELDING 2.DRY WELDING

CLASSIFICATION

WET WELDING: * In the wet welding the welding is performed underwater, directly exposed to the wet environment. * Supply is connected to the welder/driver via cable hoses. * MAW (Manual arc welding ) is commonly used in this welding for repairing purpose

ADVANTAGES: * The versatility and low cost. * Less costlier then dry welding. * Tensile stress is high * No west of time

DISADVANTAGES: * Decreases impact strength and losses * Poor visibility in water * Chances of cracking * Lack of experienced worker

DRY WELDING:

• A chamber is created near the area is to be the welded. • A welder does the job by staying inside the chamber.• Gas metal arc welding is the best process for this welding.

ADVANTAGES: * Welder/diver safety * Good quality weld * Surface monitoring * Non destructive testing

DISADVANTAGES: * This welding require large quantities of complex equipment * Cost is extremely high * For more depth more energy is required * Can not be weld if weld spot is unreachable places

Repairing and maintenance of ships Constructions of large ships Constructions for tapping sea resources

Temporary repair work

APPLICATION

Electric shock Explosion

Risk is to the life or health of the welder Inspection of welds

Hydrogen and Oxygen are produced during welding

RISK INVOLVED

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