UNDERWATER WELDING

First under water welding by British Admiralty – Dockyard

In 1946, special waterproof electrodes were developed in   Holland by ‘Van der Willingen’ 

INTRODUCTION TO UNDERWATER WELDING

We cant lift ship and then repair it. Hence comes the use of underwater welding

Types of underwater welding 

Wet welding

Dry welding

DRY WELDING

Hyperbaric welding is the process in which a chamber is sealed around the structure  to be welded and is filled with a gas ( He and Oxygen) at the prevailing pressure. 

Dry welding can be of two types

• Large habitat

• Mini habitat                 

                                        Mini habitat for underwater welding. 

                                 

Large habitat for underwater welding 

   

Large habitat underwater welding

                        

Advantages of dry welding 

•      Welder /diver safety

•      Good weld quality

•      Surface monitoring

Disadvantages

•      Higher cost of process, training, etc

•      Large quantity of  costly and complex equipments

•      More deep, more energy requirement.

•      Cant weld if weld spot is at unreachable place

Wet welding  

•      Simply means that job is performed directly in the water

•      It involves using special rod  and is similar to the process in ordinary air welding                                                                                                                                                                                                                               

FIGURES SHOWING WET WELDING

Requirements

Effect of wet environment 

•      WATER-------------àHYDROGEN + OXYGEN

•      Dissolve in weld pool

•      Solubility decrases and then comes out -à porosity

•      Oxygen as solid , liquid inclusions or gases

•      Hydrogen combines with oxygen forming vapour 

Advantages of wet welding

•      Cheapest

•      Fastest

•      Tensile strength is high

•      Ease of access the weld spot

     •      No waste of time in constructing habitat 

Disadvantages

•      Rapid quenching decreases impact strength, Ductility.

•      Hydrogen embrittlement.

•      Poor visibility in water.

•      Higher energy density of hydrogen, higher efficiency.

Requirements for underwater welding

•      Underwater Oxygen-Arc Welding Torches.-

                       Collet or grip

                        Oxygen valve

                        Flash arrester

•      Waterproofing Surface Electrodes.

                       Epoxy 152

                        Lee lac 30-l2093

                        Polyurethane 

MY NEXT PROJECTS
1)THEO JANSEN MECHANISM
2)Goodyear’s future tires for self-driving cars: four maglev spheres
3)Solar Roadways
4)PELTON WHEEL TURBINE