Twi Welddefect

8/18/2019 Twi Welddefect

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Welding InspectionDefects/Repairs

Course Reference WIS 5Copyright © 2003 TWI Ltd M.S.Rogers


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WeldWeld DefectsDefects

Defects which may be detected by is!al i"spectio" ca"

be gro!ped !"der fie headi"gs

# Crac$s

# %olid i"cl!sio"s

# %!rface a"d profiles

# &isalig"me"t 'set(!p

irreg!larities)

# *as pores a"d

porosity

# Lac$ of f!sio"

# &echa"ical damage

# +are"t material damage

# &iscella"eo!s


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Copyright © 2003 TWI Ltd M.S.Rogers


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Crac$sCrac$s



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Crac$sCrac$s

Crac$s that may occ!r i" welded materials are ca!sed

ge"erally by by ma"y factors a"d may be classified byshape a"d positio", crac$s are classed as pla"ar-

Classified by Shape

#

Lo"git!di"al

# Tra"serse

#

.ra"ched

#

Chero"

Classified by Position

#

1# Ce"treli"e

#

Crater

#

!sio" o"e

# +are"t metal



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+rocess+rocess Crac$sCrac$s

ƒ ydroge" i"d!ced cold crac$i"g'ICC)

ƒ %olidificatio" crac$i"g 'ot Teari"g)

ƒ Lamellar teari"g

ƒ Re heat crac$i"g



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Crac$sCrac$s

Lo"git!di"al pare"t metal crac$ Tra"serse weld metal crac$

Lo"git!di"al weld metal crac$ Lamellar teari"g



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Transverse crack Longitudinal crackCopyright © 2003 TWI Ltd M.S.Rogers


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I"cl!sio"sI"cl!sio"s



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*as*as CaitiesCaities

Gas pore


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*as*as CaitiesCaities

PorosityPorosity

RooRoott pipingpiping



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Cluster porosity Herring bone porosityCopyright © 2003 TWI Ltd M.S.Rogers


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%olid%olid I"cl!sio"sI"cl!sio"s

Slag inclusions are defined as a non-metallic inclusion

caused by some welding process ƒ %lag origi"ates from weldi"g

fl!4

ƒ &* a"d TI* weldi"g

process prod!ce silica%lag i"cl!sio"s Lac$ of sidewall

f!sio" withassociated slag

i"cl!sio"s

ƒ %lag is ca!sed byi"ade5!ate clea"i"g

ƒ 6ther i"cl!sio"s i"cl!det!"gste" a"d copper

i"cl!sio"s from the TI* a"d+arallel slag li"es Lac$ of i"ter!"

f!sio" 7 slag

Copyright © 2003 TWI Ltd

&* weldi"g processM.S.Rogers


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Interpass slag inclusionsCopyright © 2003 TWI Ltd

Elongated slag linesM.S.Rogers


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Lac$Lac$ of of !sio"!sio"



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%!rface%!rface a"da"d profileprofile DefectsDefects

I"complete filled grooe

7 Lac$ of sidewall f!sio"

1

ƒ

+oor welder s$ill

ƒ I"correct electrode

ma"ip!latio"

ƒ

rc blow

ƒ I"correct weldi"g

c!rre"t/oltage

2

8- Lac$ of sidewall f!sio"

2- Lac$ of i"ter(r!" f!sio"

ƒ I"correct trael speed

ƒ I"correct i"ter(r!" clea"i"g



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6erlap6erlap

An imperfection at the toe or root of a weld caused by

metal flowing on to the surface of the parent metal

without fusing to it

ƒ Co"tami"atio"

ƒ %low trael speed

ƒ I"correct weldi"g tech"i5!e

ƒ C!rre"t too low



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6erlap6erlap

ToeToe OverlapOverlap



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RootRoot DefectsDefects

ƒ

Low mps/olts

I"complete root f!sio"

I"complete root pe"etratio"

ƒ Large Root face

ƒ

%mall Root *ap

ƒ ast Trael %peed

ƒ I"correct 9lectrode "gle

ƒ Co"tami"atio"

ƒ rc blow



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RootRoot DefectsDefects

Lack of root fusionLack of root Penetration



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Lack of root penetration Lack of root fusionCopyright © 2003 TWI Ltd M.S.Rogers


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%!rface%!rface a"da"d +rofile+rofile



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+rofile+rofile DefectsDefects

I"complete filled grooe +oor cap profile

Poor cap profiles and excessive

cap reinforcemens ma! lead o

sress concenraion poins ahe weld oes and will also

conri"ue o overall poor oe

"lend 94cessie cap height



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Excess cap reinforceentCopyright © 2003 TWI Ltd Incoplete filled grooveM.S.Rogers


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+rofile+rofile DefectsDefects

Poor stop!starts



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&iscella"eo!s&iscella"eo!s DefectsDefects

• 94cessie c!rre"t• Damp electrodes

• Co"tami"atio"

• I"correct wire feed speed

whe" weldi"g with the &*

"patter



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&iscella"eo!s&iscella"eo!s DefectsDefects

ƒ ccide"tal stri$i"g of the arc

o"to the pare"t material

ƒ a!lty electrode holder

ƒ +oor cable i"s!latio"

#rc strike

ƒ +oor ret!r" lead clampi"g



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:"derc!t:"derc!t

An irregular groove at the toe of a weld run in the

parent metal • 94cessie amps/olts

• 94cessie trael speed

• I"correct electrode a"gle

• 94cessie weai"g• I"correct weldi"g tech"i5!e

• 9lectrode too large

M.S.Rogers


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CapCap :"derc!t:"derc!t

&eas!red&eas!red i"i" bothboth Le"gthLe"gth ;; DepthDepth



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Root undercutCopyright © 2003 TWI Ltd Cap undercut M.S.Rogers


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%hri"$age%hri"$age *rooe*rooe

M.S.RogersCopyright © 2003 TWI Ltd

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Y A shallow groove caused by contraction in the weld metal along each side of the penetration bead

ƒ I"s!fficie"t weld metal

deposited i" the root pass

%hri"$age grooe

ƒ Too fast a cooli"g rate d!ri"g

the applicatio" of the root

bead pass

ƒ

+oor weldi"g tech"i5!e


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Co"caeCo"cae RootRoot

M.S.RogersCopyright © 2003 TWI Ltd

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Y A shallow groove, which may occur in the root of a butt weld

ƒ Root faces too large

ƒ Root gap too large

Co"cae root

ƒ 94cessie bac$ p!rge press!re

d!ri"g TI* weldi"g

ƒ 94cessie root bead gri"di"g

before the applicatio" of theseco"d pass


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%!c$l "ac#l


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94cessie94cessie RootRoot +e"etratio"+e"etratio"

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YRoot penetration bead in excess in accordance with therelevant specification being used

ƒ Root faces too small

ƒ Root gap too large

94cessie root pe"etratio"

ƒ 94cessie amps/olts

ƒ

%low trael speed


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.!r".!r" Thro!ghThro!gh

A localized collapse of the weld pool due to excessive

penetration resulting in a hole in the root run

ƒ igh mps/olts

ƒ

%mall Root face

ƒ Large Root *ap

.!r" thro!gh ƒ %low Trael %peed



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RootRoot Co$i"g/64idiedCo$i"g/64idied RootRoot

ƒ Loss or i"s!fficie"t bac$

p!rgi"g gas

ƒ &ost commo"ly occ!rs

whe" weldi"g stai"lesssteels

ƒ +!rgi"g gases i"cl!de

argo", heli!m a"doccasio"ally "itroge"


C tC t +i

+i


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Crater Crater +ipe+ipe

Crater pipe is a shrinkage defect and not a gas defect, it

has the appearance of a gas pore in the weld crater

ƒ Too fast a cooli"g rate

Crater crack&"tar crack'

ƒ Deo4idiatio" reactio"sa"d

li5!id to solid ol!me

cha"ge

ƒ Co"tami"atio"


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C tC t +i

+i


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Crater Crater +ipe+ipe

WeldWeld crater crater

Crater Crater pipepipe


C tC t +i /C $

+i /C $


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Crater Crater +ipe/Crac$s+ipe/Crac$s

Crater Crater CracksCracks

Crater Crater pipepipe



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&echa"ical&echa"ical DamageDamage


& h i l&echa"ical DDamage


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&echa"ical&echa"ical DamageDamage

&echa"ical damage ca" be defi"ed as a"y s!rface material

damage ca!se d!ri"g the ma"!fact!ri"g process-This ca" i"cl!ded damage ca!sed by<

ƒ *ri"di"g

ƒ

ammeri"g

ƒ Chiselli"g

ƒ Chippi"g

ƒ

.rea$i"g off welded attachme"ts 'tor" s!rfaces)

ƒ :si"g "eedle g!"s to compress weld cappi"g r!"s



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%e%ett(!p(!p Irreg!laritiesIrreg!larities


%%ett I l iti

!pIrreg!larities


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%e%ett(!pIrreg!larities(!pIrreg!larities

$inear misali%nmen is measured

from he lowes plae o he

hi%hes poin of he cap

+late/pipe Li"ear &isalig"me"t

'i(Lo)

&n%ular misali%nmen is

measured in de%reeso

"g!lar &isalig"me"t


Li"earLi"ear &isalig"me"t

&isalig"me"t


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Li"ear Li"ear &isalig"me"t&isalig"me"t

ighest poi"t

of the capmm

Lowest plate


+ t+ t & t i l& t i l D f tD f t


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+are"t+are"t &aterial&aterial DefectsDefects

weldi"g i"spector sho!ld also i"spect the pare"t

material for a"y isible defects

&echa"ical damage Lap

Lami"atio"

%egregatio" li"e

Copyright © 2003 TWI Ltd


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