welding technology & inspection method.ppt

8/17/2019 Welding Technology & Inspection Method.ppt

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FUNDAMENTAL OF WELDINGFUNDAMENTAL OF WELDING

WELDING : Welding is a joining process in whichmetals are heated, melted and mixed to produce a

joint with properties similar to those of thematerials being joined

!D"!N#!GE : $ortable, permanent, stronger than theparent materials with a %ller metal, the mosteconomical method to join in terms of material usageand fabrication costs

DI&!D"!N#!GE : Expensi'e manual Labor, highenerg( and dangerous, di)icult to disassemble andremo'e the defects


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APPLICATIONS APPLICATIONS

*onstructions, $iping, pressure 'essels

+oilers and storage tans, &hipbuilding, !erospace

!utomobile and -ailwa(s

!utomation . /achine, !utomatic and-obotic welding


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WELDING PROCESS WELDING PROCESS

*0//0NL1 2&ED WELDING $-0*E&&E& !-E:

&3IELDED /E#!L !-*WELDING4&/!W5

G!& /E#!L !-* WELDING4G/!W5 G!& #2NGEN !-* WELDING4G#!W5 &2+/E-GED !-* WELDING4&!W5 061!*E#1LENE WELDING40!W5

7L26 *0-ED !-* WELDING47*!W5 ELE*#-0&L!G WELDING D WELDING -E&I!N*E WELDING4-W5


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SMAW SMAW

&/!W 4&hielded /etal !rc Welding5 is

also nown as:&tic welding

/anual /etal !rc Welding4//!W5


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SMAW SMAW When an arc is struc between the metal rod 4electrode5 and the

wor piece, both the rod and wor piece surface melt to form aweld pool

&imultaneous melting of the 8ux coating on the rod will form gas

and slag which protects the weld pool from the surrounding

atmosphere

#he slag will solidif( and cool /ust be chipped o) the weld bead once the weld run is complete

or before the next weld pass is deposited


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Measurement ofundercut dept !"t #WAC $a$e%Underc

ut

SMAW SMAW

http://en.wikipedia.org/wiki/Image:Arc_welding_electrodes_and_electrode_holder.triddle.jpg


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SMAW SMAW

#he electrode coating is the feature which classi%es the

'arious t(pes of electrodes It actuall( ser'es thefollowing 7i'e separate function

&3IELDING: *oating decomposes to form a gaseousshield

DE.06ID!#I0N : *oating pro'ides a 8uxing action toremo'e the 09 other atmospheric gases

!LL01ING : *oating pro'ides additional allo(ingelements for the weld deposit

I0NI;ING : *oating impro'es electrical

characteristics to increase arc stabilit( IN&2L!#ING : #he solidi%ed slag pro'ides insulatingblanet to slow down the weld metal cooling rate


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SMAW SMAW

ELE*#-0DE IDEN#I7I*!#I0N &1E/

E < = > ? @ELE*#-0DE

#EN&ILE -ENG#3 4si5

$0&I#I0N

#1$E 07*0!#ING

*2--EN#


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WELDING POSITIONS WELDING POSITIONS


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GUESS T&E WELD POSITIONGUESS T&E WELD POSITION


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SMAW SMAW

&IGNI7I*!N*E 07 #3I-D DIGI# 07 &/!W

IDEN#I7I*!#I0N'() < INDI*!#E& &2I#!+LE 70- 2&E IN !N1$0&I#I0N

'*) < /E!N& #3!# /0L#EN /E#!L I& &0 7L2ID#3!# ELE*#-0DE *!N 0NL1 +E 2&ED IN 7L!#0- 30-I;0N#!L 7ILLE# $0&I#I0N

'+) < ELE*#-0DE I& &2I#!+LE 70- WELDING IND0WN3ILL $-0G-E&&I0N

',) < 3!& N0 &IGNI7I*!N*E


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&IGNI7I*!N*E 07 L! DIGI# 07 &/!W

IDEN#I7I*!#I0N

SMAW SMAW


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SMAW SMAW

CURRENT CONDITIONS

ELECTRODE SIZE(mm) AMPS.(CURRENT)

2.50 70 – 100

3.15 100 – 140

3.20 100 – 140

4.00 140 – 180

5.00 180 – 240

6.30 240 – 280

GENERAL T&UM-.RULE FOR CALCULATIGCURRENT/

0 DIA OF ELECTRODE 1 +2 3 45. *20 DIA OF ELECTRODE 1 +2 3 45. *2


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SMAW SMAW

LOW &6DROGEN ELECTRODES:

#hose Electrode ending with#hose Electrode ending with AA7)8)9) OR ':)7)8)9) OR ':) are classi%ed as BL0W 31D-0GENC #(pesare classi%ed as BL0W 31D-0GENC #(pes

#o /aintain the low h(drogen moisture#o /aintain the low h(drogen moisture

content, the( must be stored in their originalcontent, the( must be stored in their original

factor( sealed container or an acceptable storagefactor( sealed container or an acceptable storage

o'eno'en

0'en should be heated electricall( ha'e0'en should be heated electricall( ha'e

temperature control capabilit( in the range oftemperature control capabilit( in the range of

?>?>>> to >to >>> **


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SMAW SMAW

AD#ANTAGES/EFuipment is relati'el( simple, inexpensi'e EFuipment is relati'el( simple, inexpensi'e

portableportableNumerous t(pes of electrodes < #he processNumerous t(pes of electrodes < #he process

considered as Fuite 'ersatileconsidered as Fuite 'ersatile

LIMITATIONS/&$EED < Welder periodicall( stop welding &$EED < Welder periodicall( stop welding

replace consumed electrode with new onereplace consumed electrode with new one#here is a la(er of solidi%ed slag which must be#here is a la(er of solidi%ed slag which must be

remo'ed which a)ects the producti'it(remo'ed which a)ects the producti'it(70- L0W 31D-0GEN ELE*#-0DE 2&ED :.70- L0W 31D-0GEN ELE*#-0DE 2&ED :.

#he( reFuire to store in an appropriate#he( reFuire to store in an appropriate

electrode baing o'en which will help toelectrode baing o'en which will help to

maintain their low moisture le'elsmaintain their low moisture le'els


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GMAW GMAW

Meta; Inert Gas We;d"n$ 0MIG3 / 0nl( inert gases

or gas mixtures are used for the shielding gas when/IG welding #(pical inert gases used for /IGwelding are argon and helium #hese gases areusuall( used for /IG welding of aluminum and other

non.ferrous metals

Meta; Act"


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GMAW GMAW General !rrangement

WI-E *0N#-0L WI-E 7EED /0#0- $0WE- &02-*E !rJ*09 G!& *1LINDE-


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GMAW GMAW

Ad


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GTAW GTAW


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GTAW GTAW

#he G#!W welding process uses a non.consumable

tungsten electrode to pro'ide an arc

7iller metal, when reFuired, is fed from a separate%ller rod

! shielding gas, eg argon, is fed through thewelding gun to the weld area and pro'ides a gasshield to pre'ent contamination b( the atmosphericgases

No 8uxes are used with the processWhen the arc onl( is used to produce the weld,without the addition of separatel( fed %ller wire,the process is nown as !utogenous G#!W


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SAW SAW

&!W is de%ned as an arc welding process which produces

coalescence of metals b( heating them with an arc or arcsbetween a bare metal electrode or electrodes and the wor piece$ressure is not used and %ller metal is obtained from theelectrode and sometimes from a supplementar( welding rod


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SAW SAW

AD#ANTAGES

3igh weld metal Kualit(

&mooth and uniform weld bead with no spatters

Extremel( high deposition rate and welding speed

3igh !rc time can be achie'ed through automation

/inimum operator fatigue

LIMITATIONS

3igh initial cost

Limited welding positions

-eFuirement of special jigs and %xtures

Di)icult( in welding low thicness metals

7ull penetration weld joints not possible from single side


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O16 ACET6LENE WELDINGO16 ACET6LENE WELDING

Tere are tree d"st"nct =ame used "n t"s metod

Te neutra; =ame EFual Fuantities of ox(gen and acet(lene Distinct inner white cone with a rounded tip &uitable for all carbon steel, cast irons, low allo( steels andaluminum

Te car>ur"?"n$ 0car>on"?"n$3 =ame &light excess of acet(lene 7eather around the inner white cone 2sed for welding of high carbon steels and for hard surfacing

Te o@"d"?"n$ =ame 3as an excess of ox(gen Inner white cone is shorter and sharper than the neutralcone #his 8ame is suitable for brass, brone, inc applications,

2sed for brone welding and braing


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OX!"AS #ELDIN" (C$%&'.)

T** D+,&+%-& /m*



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App;"cat"on/

Low.carbon steel, low.allo( steel, cast steel, and wrought iron areeasil( welded b( the ox(.gas process ! 8ux is not necessar( withthese metals because their oxides melt at a lower temperaturethan the base metal During the welding process, (ou shouldenclose the molten puddle with the 8ame en'elope to ensure the

molten metal does not contact the air If the metal is exposed tothe air, it will oxidie rapidl( 1ou also should a'oid o'erheatingthe metal

!s the carbon content of a steel increases, welding becomes moredi)icult &teels whose carbon content is within the >.percent to

>.percent range are welded with a slightl( carburiing 8ame


#he melting is slow compared with arc processes,limiting the speed of wor #he weld pool is shieldedfrom atmospheric contamination b( the burnt gasmixture which can be made mildl( oxidiing or

reducing

L"m"tat"on/


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T6PE OF OINTS B WELDST6PE OF OINTS B WELDS

Tpes of o"nts Tpes of We;ds-utt o"nt F";;et !e;d

Corner o"nt Groo


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-UTT OINT

! joint between two members alignedapproximatel( in the same plane

Di)erent Edge &hapes and &(mbols for some+utt.Moints



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CORNER OINT

! joint between two members located at rightangles to each other

Di)erent Edge &hapes and&(mbols for some *orner. Moints



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T OINT

! joint between two members locatedapproximatel( at right angles to eachother in the form of a #

D"erent Ed$e Sapesand Sm>o;s for someT.o"nts



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LAP OINT

! joint between two o'erlappingmembers

D"erent Ed$e Sapes andSm>o;s for some Lap.

o"nts



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EDGE OINT

! joint between the edges of two or more parallel or nearl(

parallel members

D"erent Ed$e Sapesand Sm>o;s for someed$e.o"nts



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T6PE OF OINTS B WELDST6PE OF OINTS B WELDSFILLET WELD

#hese welds are roughl( triangular in cross sectionand between two surfaces not in the same planeand the weld metal is substantiall( placedalongside the components being joined Depositedweld metal is external to the pro%le of the weldedelements

We;dSm>o;

MITRE

CON#E

1

CONCA# E


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GROO#E WELD

#he weld metal is substantiall( placed inside thecomponents being joined Deposited weld metal is internalto the pro%le of the welded elements




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G-00"E WELD #1$E&



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$L2G !ND &L0# WELD&

2sed withpreparedholes

Weld&(mbol




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&$0# 0- $-0ME*#I0N WELD

Weld at theinterface of themember 2sed without

prepared holes 2se !rc or-esistance We;d

Sm>o;



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GUESS T6PE OF OINTGUESS T6PE OF OINT


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WELDING S6M-OLWELDING S6M-OL


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-eference Line !rrow

#ail omitted whenreference notused

Arro! connectsreference ;"ne to arro!s"de mem>er of o"ntor arro! s"de of o"nt

#ail

-eference Line must alwa(s be horiontal, !rrow

points to the line or lines on drawing which clearl(identif( the proposed joint or weld area

#he tail of the welding s(mbol is used to indicatethe welding or cutting processes, as well as thewelding speci%cation, procedures, or the

supplementar( information to be used in maing



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FILLET WELD EHUAL LEGFILLET WELD EHUAL LEG




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FILLET WELD. LENGT&FILLET WELD. LENGT&




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FILLET WELD. STITC&FILLET WELD. STITC&




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FILLET WELD. UNEHUAL LEGFILLET WELD. UNEHUAL LEG




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GROO#E WELD. -E#ELGROO#E WELD. -E#EL




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GROO#E WELD . # GROO#E WELD . #




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GROO#E WELD. # GROO#E WELD. #



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GUESS T&E WELDING S6M-OLGUESS T&E WELDING S6M-OL


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WELDING INSPECTION WELDING INSPECTION


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WELDING INSPECTION WELDING INSPECTION

WELDING DEFECTSWELDING DEFECTS


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T6PE OF DEFECTST6PE OF DEFECTS

Defects can >e c;ass"ed as/ Defects "n


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T6PE OF DEFECTST6PE OF DEFECTS

Geometr"c defects2ndercutExcessi'e reinforcement+urn through or excessi'e

penetrationDistortion Improper weld pro%le

Meta;;ur$"ca; defects

*racsGas porosit( !rc stries&tructural notches




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REASONS FOR DEFECTSREASONS FOR DEFECTS

Lac of now.how and experience ofwelderJoperator

Welding process and characteristics +ase metal composition

Defecti'e welding %ller metals Moint design Welding en'ironment 4wind, %t.up,

temperature5




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LACK OF FUSIONLACK OF FUSION

It in'ol'e incomplete melting and fusion of someportion of weld metals in joints It ma( occureither between parent metal and weld metal orbetween two la(ers of weld metals #hesebasicall( occur in fusion and pressure welding

REASONS/ Improper manipulation of electrodes Incorrect position of electrodes Low welding current

#oo rapid arc ad'ance $oor edge preparationDISAD#ANTAGES/ Lower strength of joints &tress concentration will occur




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LACK OF FUSIONLACK OF FUSION




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INCOMPLETE PENETRATIONINCOMPLETE PENETRATION

#his is lac of penetration of the weldsthrough the thicness of the joints #hisusuall( occur at the root of the weld orbetween deposits made from both sides

REASONS/

Incorrect joint design Improper welding parameters particularl(

currents Incorrect electrode sie

DISAD#ANTAGES/ It ad'ersel( a)ects the joints which aresubjected to either tensile or bendingstresses

It can initiate brittle fracture under static or

d(namic loads




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INCOMPLETE PENETRATIONINCOMPLETE PENETRATION




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FOREIGN INCLUSIONFOREIGN INCLUSIONSLAG INCUSION/ #his is formed due to entrapment of oxides

and non metallic solids in the weld depositsor between the weld metals and base metals-apid solidi%cation at lower temperature ofweld metals pre'ent the release of suchentrapments

O1IDES FILMS/ ! thin %lm of oxides forms due to inadeFuate

shielding in case of /IG welding Ita)ects the ductilit( of weld metals




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FOREIGN INCLUSIONFOREIGN INCLUSION

TUNGSTEN INCLUSION/ In case of #IG welding some particle ma( get

deposits from tungsten electrodeREASONS/

Improper preparation of groo'e $reheating the base materials is not done

properl( Improper sie of electrode

InadeFuate shielding in case of oxides %lms




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FOREIGN INCLUSIONFOREIGN INCLUSION

TUNGSTEN INCLUSION/ In case of #IG welding some particle ma(

get deposits from tungsten electrodeREASONS/ Improper preparation of groo'e $reheating the base materials is not done

properl(

Improper sie of electrode InadeFuate shielding in case of oxides %lms




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GEOMETRIC DEFECTSGEOMETRIC DEFECTS

UNDERCUT/It represent a depression into the base

metal adjacent to the toe of the weldand if it forms a notch it is danger for

the welds




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REASONS/ In correct choice of current range

Improper tra'el speed

Improper design and poor %t.up

Not following the welding procedure

Improper electrode sie and wea'ing

GEOMETRIC DEFECTSGEOMETRIC DEFECTS



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GEOMETRIC DEFECTSGEOMETRIC DEFECTSWELDING DEFECTSWELDING DEFECTS



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DEFECTS 0UNDERFILL3DEFECTS 0UNDERFILL3WELDING DEFECTSWELDING DEFECTS



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METALLURICAL DEFECTSMETALLURICAL DEFECTSCRACKS/ #hese are linear ruptures of the metals under

stress

CRATOR CRACKS/

*racs formed from a circular surface withdepression either in the welds or at the end of thewelds

POROSIT6/ $orosit( is the presence of the gas pocets of

'oids caused b( the entrapment of the gas

e'ol'ed during weld metal solidi%cation




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METALLURGICAL DEFECTSMETALLURGICAL DEFECTS WELD DEPOSITS/

&ometimes in a particular one excess weldsaccumulate due to high current which can causeformation of notches and ultimatel( a)ect fatiguestrength

REASONS/ 2ne'en heating and cooling rate Improper shielding, rust on the weld face, too much

generation of gas in weld pool, sudden cooling of slag




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METALLURGICAL DEFECTSMETALLURGICAL DEFECTS




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DEFECTSDEFECTS

0"E-L!$

-00#*0N*!"I#1



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PAUSE FOR T&OUG&TSPAUSE FOR T&OUG&TS


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GUESS T6PE OF DEFECTSGUESS T6PE OF DEFECTS


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welding technology & inspection method.ppt

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