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Seminar Reort on Under Water Welding

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Seminar Reort on Under Water Welding Powered By Docstoc
					UNDER WATER
WELDING

   By Snehasmita Mallick
WELDING
 Welding is the process of joining two pieces of
  metals or non-metals, It results in a Joint i.e
  equivalent in compositions & characteristics of
  metal joint.
 There are various types of process is used such as
    1.   Gas Welding
    2.   Arc Welding
UNDER WATER WELDING
   Underwater welding refers to a number of
    distinct welding processes that are performed
    underwater.
UNDERWATER WELDING PROCESS IS
CATEGORIZED INTO TWO DIVISIONS.

 Wet welding
 Dry welding
WET WELDING
   In the case of wet welding, the operation is
    completed under water, directly exposed to the
    wet environment. For this purpose, a different
    type of electrode is used.
THE ADVANTAGES OF WET WELDING:
 The expenditure is very minimal. Unlike in the
  case of dry welding.
 The speed of the operation is extremely high.

 As the equipments are very minimum, the
  welding can be performed in a shorter time with
  minimal planning.
THE DISADVANTAGES OF WET
WELDING:
 The weld is quenched is very fast under water. It
  decreases the ductility and impact strength an
  also makes the weld very porous.
 The visibility of the welder is not up to the
  required level.
 The amount of voltage that can b employed is
  very limited. Care has to be taken so that the
  welder is not harmed by probable electrical
  shocks.
DRY WELDING
 Otherwise known as Hyperbaric welding
 The whole operation is completed in a chamber,
  sealed around the structure to be welded.
 The Gas Tungsten Arc welding process is used.
THE ADVANTAGES OF DRY WELDING:
 Welding can be carried out without getting
  affected by ocean currents and marine animals.
 Better quality welds can be used.

 From the surface itself, there is a possibility of
  visually monitoring joint preparation and pipe
  alignment.
THE DISADVANTAGES OF DRY
WELDING:
 The chamber is very complex. Large support
  equipment is needed at the surface to support the
  chamber.
 The expense will be very high. The cost increases
  proportionately to the depth under water.
 The chamber has limited reusability.
RISKS & PRECAUTIONS:
 The welder has to protect himself from electric
  shocks.
 The welder has to be insulated.

 The welder has to take precaution because
  nitrogen will be built up in the blood stream of
  the welder, when exposed to air at high pressure
  under the water surface.
UNDERWATER WELDING TECHNIQUES
 Conventional Underwater Welding
  Techniques
 Advanced Underwater Welding Technique
CONVENTIONAL UNDERWATER
WELDING TECHNIQUES
 Shielded Metal Arc Welding
 Flux Cored Arc Welding

 Tungsten Inert Gas Welding
SHIELDED METAL ARC WELDING
   For underwater wet welding
    with shielded metal arc
    welding (SMAW) technique,
    direct current is used and
    usually polarity is straight.
FLUX CORED ARC WELDING
TUNGSTEN INERT GAS WELDING
ADVANCED UNDERWATER WELDING
TECHNIQUE
 Friction welding (FRW)
 Laser Welding
FRICTION WELDING (FRW)
LASER WELDING
CHARACTERISTICS OF A GOOD
UNDERWATER WELDING
 Requirement of inexpensive welding equipment,
  low welding cost, easy to operate and flexibility of
  operation in all positions.
 Minimum electrical hazards, a minimum of 20
  cm/min welding speed at least.
 Permit good visibility.

 Produce good quality and reliable welds.

 Operator should be capable in supporting
  himself.
 Easily automated.
APPLICATION OF UNDERWATER
WELDING
 Offshore construction for tapping sea resources.
 Temporary repair work caused by ship’s
  collisions or unexpected accidents.
 Salvaging vessels sunk in the sea.

 Repair and maintenance of ships.

 Construction of large ships beyond the capacity of
  existing docks.
DEVELOPMENTS IN UNDER WATER
WELDING
 Wet welding has been used as an underwater
  welding technique for a long time and is still
  being used. With recent acceleration in the
  construction of offshore structures underwater
  welding has assumed increased importance.
 This has led to the development of alternative
  welding methods like friction welding, explosive
  welding, and stud welding. Sufficient literature is
  not available of these processes.
SCOPE FOR FURTHER DEVELOPMENTS
 THOR – 1 (TIG Hyperbaric Orbital Robot) is
  developed where diver performs pipefitting,
  installs the trac and orbital head on the pipe and
  the rest process is automated.
 Developments of diverless Hyperbaric welding
  system is an even greater challenge calling for
  annexe developments like pipe preparation and
  aligning, automatic electrode and wire reel
  changing functions, using a robot arm installed.
CONCLUSION
REFERANCE
 www.wikipedia.org
 www.google.com

 www.seminarproject.net
THANK YOU

				
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