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Welding Defects

INTRODUCTIONBackground:

Quality Manager request Welding Engineer to conduct welding defects training to Quality Personnel

Purpose:

• Visual Inspection of welds• Identification of welding defects• Weld Quality Awareness• Reference Specification

OUTLINE PER DEFECT

1. Definition of welding defect2. Visual Indication of the defect3. Possible Causes4. Corrective Action

LIST OF DEFECTS TO BE COVERED

1. Porosity2. Lack of Penetration3. Lack of Fusion4. Lack of Inter run fusion(Capping)5. Undercutting6. Cracking7. Excessive Spatter8. Burn through9. Arc Strike10.Pinhole

WELDING DEFECT

Any physical irregularity in the weld or HAZ, which may or may not affect the usefulness of a part.Porosity• A cavity caused by entrapped gases of molten metal

Possible Causes• Low/high shielding gas flow• Draft conditions• Contaminated weld preparation

Corrective Action• Ensure sufficient gas flow• Check workshop condition

before welding• Pre-clean weld area

LACK OF ROOT PENETRATION

The failure of metal to extend into the root of a joint

Possible Causes• Root face too large/small• Incorrect electrode angle• Travel speed too high for current

Corrective Action• Use correct gap (WPS)• Gun manipulation• Use correct travel

speed(WPS)

LACK OF FUSION

Lack of union between:• Weld metal and parent metal• Parent metal and parent metal• Weld metal and weld metal

Possible Causes• High/too low welding currents• Contaminated weld preparation• Travel speed too low

Corrective Action• Remove all oxide before welding• Ensure correct parameters are

used

LACK OF INTER RUN FUSION

Lack of union between the runs visible in capping or filler.

Possible Causes• Incorrect parameter settings• Welder technique

Corrective Action• Use correct parameters• Avoid weaving where possible

UNDERCUTTING

An irregular groove at the toe of a run in the parent materialAppears at the edge of the weld

Possible causes• Travel speed too high• Welding voltage too

high• Excessive welding

current

Corrective action• Decrease travel

speed• Use leading torch

angle

CRACKS

A linear discontinuity produced by fracture

Possible Causes• Incorrect wire chemistry• Poor quality of material being welded• Weld bead too small

Corrective Action• Use correct welding

consumables• Weld as per WPS instruction

EXCESSIVE SPATTER

Molten metal droplets that are thrown out from the fusion zone

Possible Cause• Arc voltage too low• Excessive arc length• Damp electrodes

Corrective Action• Use Anti spatter• Use correct voltage(WPS)

BURN THROUGH

A localized collapse of the molten pool resulting in a hole in the weld run

Possible Causes• Excessive Penetration• Excessive amperage• Excessive root grinding

Corrective Action• Use correct root gap as

specified on WPS

ARC STRIKE

Damage on the parent material resulting from accidental striking of an arc from the weld

Possible Causes• Electrode straying onto parent

material• Poor contact of the earth clamp• Electrode holder with poor

insulation

Corrective Action• Ensure the correct condition

of welding equipment

PINHOLE

Possible Causes• Unclean base metal surface• Rusted wire• Insufficient or damp shielding gas

Corrective Action• Preclean surfaces before

welding• Use correct and sufficient

welding consumables

A welding defect caused by high welding temperatures

WELDING GUN ANGLE

CONCLUSION• Importance of inspection• Defect Identification• WPS to be followed at all times

Transnet Welding defect specification

PD_WE_NAT_SPEC_003

EN acceptance standard

ISO 5817

ASME acceptance standard ASME B31.3

Thank you