Underwaterwelding Smnr 130417052545 Phpapp01

8/17/2019 Underwaterwelding Smnr 130417052545 Phpapp01

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UNDERWATER WELDING

Presented bySuresh Beera

12ETMM11

M.Tech/Ph.D

Materials Enineerin

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Outline• Importance Of Underwater Welding

• Principle Of Operation

• Classification

• Wet/Dry Underwater Welding

• Advantages& Disadvantages

• Risk Involved & afety

• Applications

• !"t"re cope

• References

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what is an Under water welding???

Many of us won't have heard of under water

welding but it's actually a very important thing in

many industries. Underwater welding includes a lotof dierent processes that join steel on oshore oilplatforms, pipelines & ships etc. under water. Atpresent, underwater welding becomes moresophisticated and can be done deeper. !A" hasbeen used to weld pipes at depths of #$$ ft % m(


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Principle of Operation

_ Po

wer "pply

# $

work

%nife switc

electrode

Waterproof 'lectrode

(older

• The welding circuit must include a positive type of switch,

usually a knife switch operated on the surface and commanded

y the welder and is used for safety reasons!

• "hen #$ is used with %ve polarity, electrolysis will take place

and cause rapid deterioration of any metallic components in the

electrode holder!

• &or wet welding '$ is not used on account of electrical safety

and difficulty in maintaining an arc underwater


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Underwater welding is classi)edinto two categories

."elding in-the-wet environment

#."elding in-the-dry environment

Dry welding Wet welding


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As te name implies) "nderwater wet welding is done

in an environment were te *ase metal and te arc

are s"rro"nded entirely *y water+ In wet welding ,,A

-man"al metal arc welding. is "sed+

"elding in the wet environment

A special electrode is "sed and

welding is carried o"t man"ally

"st as one does in open air

welding+

0e increased freedom of

movement makes wet welding temost effective) efficient and

economical metod+

Welding power s"pply is located

on te s"rface wit connection to

te diver/welder via ca*les


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Advantages

• ceapest and fastest metod

• tensile strengt is ig

• easy of access te weld spot

• no a*itat) no constr"ction)

• no waste of time

Disadvantages

• Rapid 1"encing decreases impact

strengt) d"ctility• (ydrogen em*rittlement)cracks

• Poor visi*ility in water


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Hyperbaric(dry) welding

(yper*aric welding is a welding in wic a cam*er is

sealed aro"nd te str"ct"re to *e welded and is filled wit

*reata*le gas-commonly eli"m containing 2+3 *ar of

o4ygen. at te prevailing press"re+ at wic te weldingis to take place+ 0is metod prod"ces ig#1"ality weld

oints

0e gas t"ngsten arc welding process is employed for

tis process+ 0e area "nder te floor of te (a*itat is

open to water+ 0"s te welding is done in te dry *"t atte ydrostatic press"re of te sea water s"rro"nding te

(a*itat

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Dry welding

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Ad t f D ldi


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Advantages of Dry welding

• "elder*diver safety

• ood +uality welds

• urface monitoring

• -on destructive testing

Disadvantages

• igher cost ofprocess,training,etc.,.

• /arge +uantity of costly andcomple0 e+uipments.

• More deep,more energy isre+uired

• 1an2t be weld,if weld spot is atunreachable places


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v vsafety

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6lectric shoc4 60plosion.

Precautins include achie!ing ade"uate electrical insulatin# the welding e"ui$%ent& shutting ' the electricity su$$lyi%%ediately the arc is e(tinguished& and li%iting the $en)circuit !ltage # **+ ,-*+. welding sets

ydrogen and 70ygen are produced during welding.

Precautins %ust /e taen t a!id the /uild)u$ # $cets# gas& which are $tentially e($lsi!e

ris4 is to the life or health of the welder*diver fromnitrogen introduced into the blood steam duringe0posure to air at increased pressure.

Precautins include the $r!isin # an e%ergency air r

gas su$$ly& stand)/y di!ers& and dec%$ressin cha%/erst a!id nitrgen

5nspection of welds.


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• Application of Underwater

Welding

• (ffshore construction for tapping searesources,

• Temporary repair work caused y

ship)s collisions or une*pected

accidents!

• +alvaging vessels sunk in the sea

• epair and maintenance of ships

• $onstruction of large ships eyond

the capacity of e*isting docks!


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• cope for f"rter developments

• "et --' is still eing used for underwater

repairs, ut the .uality of wet welds is poorand are prone to hydrogen cracking! #ry

yperaric welds are etter in .uality than wet

welds! resent trend is towards automation!

T( 1 2T yperaric (rital oot5 is

developed where diver performs pipefitting,!

• #evelopments of driverless yperaric

welding system is an even greater challenge

in developments like pipe preparation and

aligning, automatic electrode!

• This is in testing stage in deep waters!*plosive and friction welding are also to e

tested in deep waters!

!riction welding -!RW.


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R'!'R'5C'

Underwater Welding 6Present tat"s And !"t"re

cope+7yotsna D"tta ,a"mdar+Department Of

,etall"rgical And ,aterials 'ngineering) Indian Instit"te

Of 0ecnology) %aragp"r) West 8engal) India

Underwater Welding Amit ,"k"nd 7osi -,ecanical'ngineer. )7"nior Researc !ellow ,ecanical'ngineering Department )Indian Instit"te Of 0ecnology

)I+I+0 6 8om*ay

Annon) Recent Advances In Dry Underwater Pipeline

Welding) Welding 'ngineer) 9:;i*son) Dry (yper*aric Underwater Welding)Welding Instit"te+


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HANK YOU

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Underwaterwelding Smnr 130417052545 Phpapp01