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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