weld defects sis

PRACTICAL VISUAL PRACTICAL VISUAL INSPECTION OF WELDSINSPECTION OF WELDS

PRACTICAL VISUAL PRACTICAL VISUAL INSPECTION OF WELDSINSPECTION OF WELDS

Features to ConsiderFeatures to ConsiderFeatures to ConsiderFeatures to ConsiderButt welds - SizeButt welds - Size

Excess weld metal height

Root penetration

Root bead width

Weld cap width

Features to ConsiderFeatures to ConsiderFeatures to ConsiderFeatures to ConsiderButt welds - ProfileButt welds - Profile

x

x

x

Features to ConsiderFeatures to ConsiderFeatures to ConsiderFeatures to ConsiderButt welds - Toe BlendButt welds - Toe Blend

x

x

x

Features to ConsiderFeatures to ConsiderFeatures to ConsiderFeatures to Consider

Butt welds - Weld WidthButt welds - Weld Width

Welding DefectsWelding DefectsWelding DefectsWelding DefectsIncomplete root penetrationIncomplete root penetration

Causes• Too small a root gap• Arc too long• Wrong polarity• Electrode too large for joint

preparation• Incorrect electrode angle• Too fast a speed of travel for

current

a) Excessively thick root facea) Excessively thick root face

b) Too small a root gapb) Too small a root gap

c) Misplaced weldsc) Misplaced welds

d) Power input too lowd) Power input too low

e) Arc (heat) input too lowe) Arc (heat) input too low

Welding DefectsWelding Defects

Too large Too large diameter diameter electrodeelectrode

Smaller (correct) Smaller (correct) diameter electrodediameter electrode

Lack of sidewall Lack of sidewall fusion due to arc fusion due to arc deflectiondeflection

Welding DefectsWelding DefectsWelding DefectsWelding Defects


Causes• Too small a root gap• Arc too long• Wrong polarity• Electrode too large for joint

preparation• Incorrect electrode angle• Too fast a speed of travel for

current

Incomplete root FusionIncomplete root Fusion


Root concavityRoot concavity

Causes• Root gap too large• Insufficient arc energy• Excessive back purge

TIG


Excess Root PenetrationExcess Root Penetration

Causes• Excessive amperage

during welding of root• Excessive root gap• Poor fit up• Excessive root grinding• Improper welding

technique


Root undercutRoot undercut

Causes• Root gap too large• Excessive arc energy• Small or no root face

Welding DefectsWelding DefectsWelding DefectsWelding DefectsCap UndercutCap Undercut

Causes• Excessive welding

current• Welding speed too high• Incorrect electrode

angle• Excessive weave• Electrode too large


OverlapOverlap

Excess Excess weld weld

metalmetal


Lack of fusionLack of fusion

Causes• Contaminated weld preparation• Amperage too low• Amperage too high (welder increases speed of

travel)

Welding DefectsWelding DefectsWelding DefectsWelding DefectsIncompletely Filled GrooveIncompletely Filled Groove

& Lack of Side wall Fusion& Lack of Side wall Fusion

• Causes• Insufficient weld metal deposited• Improper welding technique

Welding DefectsWelding DefectsWelding DefectsWelding DefectsInter run Incompletely Filled GrooveInter run Incompletely Filled Groove

Causes• Insufficient weld metal

deposited• Improper welding technique


Gas pores / PorosityGas pores / Porosity

Causes• Excessive moisture in flux or

preparation• Contaminated preparation• Low welding current• Arc length too long • Damaged electrode flux• Removal of gas shield


Gas pores / PorosityGas pores / Porosity

Welding DefectsWelding DefectsWelding DefectsWelding DefectsInclusions - SlagInclusions - Slag

Causes• Insufficient cleaning between passes• Contaminated weld preparation• Welding over irregular profile• Incorrect welding speed• Arc length too long

Poor (convex) weld Poor (convex) weld bead profile resulted in bead profile resulted in pockets of slag being pockets of slag being trapped between the trapped between the weld runsweld runs

Smooth weld bead Smooth weld bead profile allows the profile allows the slag to be readily slag to be readily removed between removed between runsruns

Welding DefectsWelding Defects


Inclusions - TungstenInclusions - Tungsten

Causes• Contamination of weld Caused by tungsten

touching weld metal or parent metal during welding using the TIG welding process


Burn ThroughBurn Through

Causes• Excessive amperage during welding of root• Excessive root grinding• Improper welding technique


SpatterSpatter

Causes• Excessive arc energy• Excessive arc length• Damp electrodes• Arc blow


Arc StrikesArc Strikes

Causes

• Electrode straying onto parent metal

• Electrode holder with poor insulation

• Poor contact of earth clamp


Mechanical DamageMechanical Damage

Chisel MarksChisel MarksChisel Marks Pitting Corrosion Grinding Marks

Non-alignment of two abutting edgesNon-alignment of two abutting edges


2mm

Also Known as: Hi Low. Mismatch. or Also Known as: Hi Low. Mismatch. or MisalignmentMisalignment

Angular distortion.Measure the distance to the edge of the plate (50mm).Use a straight edge (rule) to find the amount of distortion then measure the space (3mm).This reported as Angular distortion 3mm in 50mm

50mm

3mm


Linear misalignment measured in mm

3 mm

Angular misalignment measured in mm

3mm

Excess weld metal heightLowest plate to highest point

Linear

Angular


Excess penetration Lowest plate to highest point

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I C Plenty001

EXAMPLE WELD INSPECTION REPORT/SENTENCE EXAMPLE WELD INSPECTION REPORT/SENTENCE SHEETSHEET

SPECIMEN NUMBER

EXTERNAL DEFECTS Defects Noted

Code or Specification Reference

Defect Type Pipe/Plate Section

1

AccumulativeTotal

2

Maximum

Allowance3

Section/Table No

4

Accept/Reject5

Excess weld metal height

Excess weld metal appearance A-C Poor blend Smooth 8 Reject

Incomplete filling A-C 22mm None 5 Reject

Inadequate weld width (PIPE) A-C N/A ------------ ---------- Accept

Slag Inclusions A-C 70mm long 50mm 9 Reject

Undercut A-C 1.5mm depth 1mm 6 Reject

Surface Porosity A-C 1.5mm 1mm 2 Reject

Cracks/Crack-like defects A-C 40mm NONE 1 Reject*

Lack of fusion A-C 22mm NONE 3 Reject

Arc strikes A-C 30x25 ------------ 7 Seek advice***

Mechanical damage A-C NONE ------------ ----------- Accept

Laps/Laminations A-C NONE ------------ ----------- Accept

Misalignment (Linear) A-C 2mm 2mm 15 Accept

Longitudinal seams (PIPE) A-C N/A ------------ ---------- Accept

PRINT FULL NAME

A-C 4mm 3mm Reject8

Signature......................................................... Date.....................................................................................*Delete which is not applicable. Use the other side for any comments.

This *pipe/plate has been examined to the requirements of code/specification .........................................and is accepted/rejected accordingly.

TWI-N/WIS-PI

22nd August 2003I C Plenty

Misalignment A-C 2mm 2mm 9 Accept

Excessive Root Penetration A-C 4mm 2mm 15 Reject

Incomplete Root Penetration A-C 50mm NONE 13 Reject

Lack of Root Fusion A-C 20mm NONE 11 Reject

Root Concavity A-C 2mm depth 1mm 10 Reject

Root Undercut A-C NONE ------------ 12 Accept

Cracks/Crack-like defects A-C NONE ------------ ---------- Accept

Slag inclusions A-C NONE ------------ 9 Accept

Porosity A-C NONE ------------ 2 Accept

Laps/Laminations A-C NONE ------------ ---------- Accept

Root DefectsRoot Defects

Comments:* Request MPI testing to confirm crack and length.** Large amount of spatter on weld face. Recommend this is removed and re

inspected.*** Recommend arc strikes are ground flush prior to MPI testing for cracks.

No Imperfection Comments Allowance

1 Cracks Confirm with penetrant testing

Not permitted

2 Porosity Individual pore Ø Maximum 1mm

3 Solid Inclusions Non metallic. Individual size Maximum 1mm

4 Solid Inclusions Metallic. Individual size Not permitted

5 Lack of Fusion Side wall/Root/Inter-run Not permitted

6 Incomplete Root Penetration

Not permitted

7 Overlap/Cold lap Weld face/Root Not permitted

8 Incompletely filled groove Not permitted

9 Linear Misalignment 0.2t Maximum 4mm

10 Angular Misalignment Maximum 10º

11 Undercut Smoothly blended 10%t Maximum d 1mm

12 Arc Strikes Area to be tested by MPI Seek advice

13 Laminations Not permitted

14 Mechanical Damage Not permitted

15 Cap Height Shall fall below plate surface 0 –3mm h Maximum

16 Penetration Bead 0 –2mm h Maximum

17 Toe Blend Smooth

18 Spatter Clean & Re-inspect Refer to manufacturer

19 Weld Appearance All runs shall blend smoothly Regular

20 Root concavity 10%t Maximum

Inspection Practice Specification Inspection Practice Specification Number Number TWI 09-09-03 TWI 09-09-03 All dimensions are given in mmAll dimensions are given in mm

TWI CAMBRIDGE MULTI-TWI CAMBRIDGE MULTI-PURPOSE WELDING GAUGE:PURPOSE WELDING GAUGE:


Visual Inspection of Welds Using the Cambridge

Multi-Purpose Welding Gauge:

Visual Inspection of Welds Using the Cambridge

Multi-Purpose Welding Gauge:

TWI CAMBRIDGE MULTI-PURPOSE TWI CAMBRIDGE MULTI-PURPOSE WELDING GAUGE:WELDING GAUGE:

TWI CAMBRIDGE MULTI-PURPOSE TWI CAMBRIDGE MULTI-PURPOSE WELDING GAUGE:WELDING GAUGE:Angle of preparation:Angle of preparation:

This scale reads from 00 to 600 in steps of 50. The angle is read against the chamfered edge of the plate or pipe.



The gauge may be used to measure misalignment of members by placing the edge of the gauge on the lower member and rotating the segment until the pointed finger contacts the higher member.

Linear Misalignment:Linear Misalignment:



The scale is used to measure excess weld metal or root penetration, by placing the edge of the gauge on the plate and rotating the segment until the pointed finger contacts the excess weld metal or root bead at its highest point.

Excess Weld Metal/Root penetration:Excess Weld Metal/Root penetration:



The gauge may be used to measure the depth of undercut by placing the edge of the gauge on the plate and rotating the segment until the pointed finger contacts the lowest depth of the undercut. The reading is taken on the scale to the left of the zero mark in mm or inches.

Undercut / mechanical damage (grinding etc)Undercut / mechanical damage (grinding etc)

weld defects sis

Documents

root gaparc

thick root faceb

largeexcessive arc energysmall

lowe arc heat input

longwrong polarityelectrode

pockets of slag

parent metalelectrode

groove lack