Weld Defect & Repair,Ham

8/16/2019 Weld Defect & Repair,Ham

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Welding InspectionDefects/Repairs


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Cracks

Solid inclusions

Surface and profiles

Misalignment (set-up

irregularities)

Gas pores and porosity

Weld DefectsWeld Defects

Lack of fusion

Incomplete enetration

Incomplete !usion

"urn #$roug$

Internal Conca%ity


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CracksCracks


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Classified by Shape

Longitudinal

#rans%erse

Classified by Position

&' Centreline

Crater

!usion one

arent metal

CracksCracksCracks t$at may occur in *elded materials are caused

generally +y many factors and may +e classified +ys$ape and position, cracks are classed as planar


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Process CracksProcess Cracks

&ydrogen induced cold cracking

(&ICC)

Solidification cracking (&ot #earing)

Lamellar tearing


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CracksCracks

Longitudinal parent metal crack

Longitudinal *eld metal crack Lamellar tearing

#rans%erse *eld metal crack


7/40Transverse crack Longitudinal crack


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InclusionsInclusions


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Gas CavitiesGas Cavities

Root piping

Cluster porosityGas pore

"lo* $ole

&erring+one porosity

Loss of gas s$ield

Damp electrodes

Contamination

'rc lengt$ too large

Damaged electrode flu.

Moisture on parent material

elding current too lo*

Gas pore


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Root pipingRoot piping

PorosityPorosity

Gas CavitiesGas Cavities


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Cluster porosity Herring bone porositySection Ref 3 Shaffie Saad


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!olid Inclusions!olid Inclusions

Slag originates from *elding

flu.

M'G and #IG *elding

process produce silicainclusions

Slag is caused +y

inade0uate cleaning

1t$er inclusions include

tungsten and copper

inclusions from t$e #IG and

M'G *elding process

Slag inclusions are defined as a non-metallic inclusion

caused by some welding process

Slag inclusions

arallel slag lines Lack of interun

fusion 2 slag

Lack of side*allfusion *it$

associated slag


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Elongated slag linesInterpass slag inclusions


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"ack of #usion"ack of #usion


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!urface and profile Defects!urface and profile Defects

Incomplete filled groo%e

2 Lack of side*all fusion

1

2

3 Lack of side*all fusion

4 Lack of inter-run fusion

oor *elder skill

Incorrect electrode

manipulation

'rc +lo*

Incorrect *elding

current/%oltage

Incorrect tra%el speed

Incorrect inter-run cleaning


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

metal flowing on to the surface of the parent metalwithout fusing to it

Contamination

Slo* tra%el speed

Incorrect *elding tec$ni0ue

Current too lo*


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Toe OverlapToe OverlapFillet weldFillet weld

Toe OverlapToe Overlaputt weldutt weld

$verlap$verlap


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%oot Defects%oot Defects

Incomplete root fusion

Incomplete root penetration

Lo* 'mps/%olts

Large Root face

Small Root Gap

!ast #ra%el Speed

Incorrect 5lectrode 'ngle

Contamination

'rc +lo*


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Lack o! root !usion Lack o! root Penetration

%oot Defects%oot Defects


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!urface and Profile!urface and Profile


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Incomplete filled groo%e oor cap profile

5.cessi%e cap $eig$t

Profile DefectsProfile Defects

Poor cap profiles and

e&cessive cap reinforcements

ma' lead to stressconcentration points at the

weld toes and will also

contri(ute to overall poor toe

(lend


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Inco"plete !illed grooveE#cess cap rein!orce"ent


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Profile DefectsProfile Defects

Poor stop$starts


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%patter

5.cessi%e current

Damp electrodes

Contamination

Incorrect *ire feed speed

*$en *elding *it$ t$e M'G

*elding process

'rc +lo*

)iscellaneous Defects)iscellaneous Defects


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)iscellaneous Defects)iscellaneous Defects

'ccidental striking of t$e arc

onto t$e parent material

!aulty electrode $older

oor ca+le insulation

oor return lead clamping

&rc strike


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*ndercut*ndercut

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

parent metal 5.cessi%e amps/%olts

5.cessi%e tra%el speed

Incorrect electrode angle

5.cessi%e *ea%ing

Incorrect *elding tec$ni0ue

5lectrode too large


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Cap *ndercutCap *ndercut

Measured in +ot$ Lengt$ 6 Dept$Measured in +ot$ Lengt$ 6 Dept$


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Cap undercutRoot undercut


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S$rinkage groo%e

!hrinka+e Groove!hrinka+e Groove

Insufficient *eld metal

deposited in t$e root pass

#oo fast a cooling rate during

t$e application of t$e root

+ead pass

oor *elding tec$ni0ue

A shallow groove caused by contraction in the weld

metal along each side of the penetration bead


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Conca%e root

Concave %ootConcave %oot

Root faces too large

Root gap too large

5.cessi%e +ack purge pressure

during #IG *elding

5.cessi%e root +ead grinding

+efore t$e application of t$e

second pass

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


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Concave %ootConcave %oot


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,&cessive %oot Penetration,&cessive %oot Penetration


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Concave root E#cessive root penetration


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Burn -hrou+hBurn -hrou+h

&ig$ 'mps/%olts

Small Root face

Large Root Gap

Slo* #ra%el Speed"urn t$roug$

A localized collapse of the weld pool due to excessive

penetration resulting in a hole in the root run


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urn t'roug'

urn

T'roug'

Burn -hrou+hBurn -hrou+h


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%oot Cokin+$&idi/ed %oot%oot Cokin+$&idi/ed %oot

Loss or insufficient +ack

purging gas

Most commonly occurs

*$en *elding stainlesssteels

urging gases include

argon, $elium and

occasionally nitrogen


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Crater pipeCrater pipe

Weld crater Weld crater

Crater PipeCrater Pipe


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Crater PipeCrater Pipe

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

has the appearance of a gas pore in the weld crater

#oo fast a cooling rate

Deo.idiation

reactions and li0uid to

solid %olume c$ange

Contamination

Crater cracksCrater cracks

(%tar cracks)(%tar cracks)

Crater pipeCrater pipe

Documents

Weld Defect & Repair,Ham