Underwater welding can be classified as either wet or dry welding. Wet welding is performed directly in water and allows for increased freedom of movement but has poorer quality welds than dry welding. Dry welding takes place inside a pressurized chamber near the work area and produces higher quality welds, most commonly using gas tungsten arc welding or gas metal arc welding processes. Underwater welding requires specialized equipment including powerful power supplies, gas manifolds, and pressurized chambers. It is used for applications like pipeline construction and repair, ship construction and maintenance, and offshore oil rig installation and repair.

1. Seminar Topic On
Under Water Weilding
Presented To:- Presented By:-
Prof R.N.Yadav Ashish Singh Yadav
(Department of ME)
Under The Supervision:- prof ajai kumar

2. Content
• Introduction
• Classification
• Principal operation
• Wet welding
• Dry welding
• Requirement
• Advantages
• Disadvantages
• Application
• Future Scope
• Conclusion
• Reference

3. INTRODUCTION
• It is process of permanent joining of two material like similar or dissimilar.
• It is the process of welding at elevated pressures, normally underwater.
• Underwater welding can either take place wet in the water itself or dry
inside a specially constructed positive pressure enclosure and hence a dry
environment.
• It is know as “hyperbaric welding” when
used in dry environment, and “underwater
welding” when in a wet environment.
Fig(1)

4. CLASSIFICATION
• Under water welding can be classified as :
i. Wet welding
ii. Dry welding
Fig(2)

5. WET WELDING
 Welding is performed under water directly exposed to the wet environment
 Key technology for repairing marine structure
 Increased freedom movement makes more effective, efficient and
economical
 Supply is connected to the welder/driver via cables or hoses
 MMA (Manual Metal Arc) welding is commonly used
process in the repair of offshore platforms.
Fig(3)

6. PRINCIPLE OF OPERATION
• The work is connected to the
positive side of dc source and
electrode to the negative
• The two parts of the circuit are
brought together and then
slightly separated
• An electric current occurs in the
gap and causes a sustained spark
which melts the bare metal
forming a weld pool
• The flux covering the electrode
melts to provide a shielding gas.
Fig(4)

7. DRY WELDING
• A chamber is created near the area to be welded and
the welder does the welding inside the chamber.
• It produces high quality weld joints .
• The gas-tungsten arc welding process is used mostly.
• Gas metal arc welding is the best
process for this welding.
Fig(5)

8.  Power supply requrements-400 amp or larger. DC
generators, motor generators and rectifiers are acceptable
power supplies
 Power converters.
 Welding Generator, Pre-Setup
 Polarity.
 Diesel Driven Welding GeneratorAmperage and Voltage
settings.
 Gas Manifolds.
Requirement
8

9. Advantages:-
 Welder/diver safety
 Good quality weld
 Surface monitoring
 Non destructive testing
 The versatility and low cost.

10. Disadvantages:-
 This welding requires large quantities of complex
equipment.
 Cost is extremely high
 Hydrogen embrittlement causes cracks.
 Poor visibility due to water contaminance

11. Applications
 Construction of pipeline inside the water.
 Temporary repair work caused by ship’s collisions,
unexpected accidents.
 Repair and maintenance of ships.
 Construction of large ships.

12. Scope of further developments
• Hyper baric welding is generally used in researched.
• Research being carried out for welding at a range of
500 to 1000m deep.
• THOR-1 (Tig Hyperbaric Orbital Robot) is developed
where diver performs pipe fitting, installs the tracks
and orbital head on the pipe and rest process is
automated.

13. Conclusion
 Wet welding is still being used for underwater repairs, but the
quality of wet welding is poor than dry welding. But the dry
welding is costlier than wet welding.
 Underwater welding is mostly employed in marine engineering
products –in installations of oil and gas rigs. Underwater
welding can be classified depending upon the types of
equipment's and the types of procedures involved. The most
common underwater welding process, known as manual metal
arc building (MMA), is employed for deep water repairing
activities.

14. References
• www.twi.com
• www.aws.com
• Production Technology- O.P.Khanna
• www.howstuffworks.com

15. THANK YOU