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Welding Imperfections and Material Inspections.pdf
- 1. Copyright © TWI Ltd 2009 CSWIP 3.1 WeldingInspection TWI Training & Examination Services Welding Imperfections And Materials Inspection Course Reference WIS 5 Course notes section reference 3.0
- 2. Copyright © TWI Ltd 2009 Features to Consider Buttwelds - Size Excess weld metal height Root penetration Root bead width Weld cap width
- 3. Copyright © TWI Ltd 2009 Features to Consider Buttwelds - Profile x x x
- 4. Copyright © TWI Ltd 2009 Features to Consider Buttwelds - Toe Blend x x x
- 5. Copyright © TWI Ltd 2009 Features to Consider Buttwelds - Weld Width
- 6. Copyright © TWI Ltd 2009 Incomplete 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 Welding Defects
- 7. Copyright © TWI Ltd 2009 a) Excessively thickroot face b) Too small a root gap c) Misplaced welds Welding Defects
- 8. Copyright © TWI Ltd 2009 e) Arc (heat)input too low d) Power input too low Welding Defects
- 9. Copyright © TWI Ltd 2009 Too large diameter electrode Smaller(correct) diameter electrode Lack of sidewall fusion due to arc deflection Welding Defects
- 10. Copyright © TWI Ltd 2009 Causes • Too smalla 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 Fusion Welding Defects
- 11. Copyright © TWI Ltd 2009 Root concavity Causes • Rootgap too large • Insufficient arc energy • Excessive back purge TIG Welding Defects
- 12. Copyright © TWI Ltd 2009 Excess Root Penetration Causes •Excessive amperage during welding of root • Excessive root gap • Poor fit up • Excessive root grinding • Improper welding technique Welding Defects
- 13. Copyright © TWI Ltd 2009 Root undercut Causes • Rootgap too large • Excessive arc energy • Small or no root face Welding Defects
- 14. Copyright © TWI Ltd 2009 Cap Undercut Causes • Excessivewelding current • Welding speed too high • Incorrect electrode angle • Excessive weave • Electrode too large Welding Defects
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- 16. Copyright © TWI Ltd 2009 Welding Defects Lack offusion Causes • Contaminated weld preparation • Amperage too low • Amperage too high (welder increases speed of travel)
- 17. Copyright © TWI Ltd 2009 Incompletely Filled Groove &Lack of Side wall Fusion • Causes • Insufficient weld metal deposited • Improper welding technique Welding Defects
- 18. Copyright © TWI Ltd 2009 Welding Defects Inter runIncompletely Filled Groove Causes • Insufficient weld metal deposited • Improper welding technique
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- 20. Copyright © TWI Ltd 2009 Welding Defects Gas 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
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- 22. Copyright © TWI Ltd 2009 Welding Defects Inclusions -Slag Causes • Insufficient cleaning between passes • Contaminated weld preparation • Welding over irregular profile • Incorrect welding speed • Arc length too long
- 23. Copyright © TWI Ltd 2009 Welding Defects Inclusions -Slag Causes • Insufficient cleaning between passes • Contaminated weld preparation • Welding over irregular profile • Incorrect welding speed • Arc length too long
- 24. Copyright © TWI Ltd 2009 Poor (convex) weldbead profile resulted in pockets of slag being trapped between the weld runs Smooth weld bead profile allows the slag to be readily removed between runs Welding Defects
- 25. Copyright © TWI Ltd 2009 Welding Defects Inclusions -Tungsten Causes • Contamination of weld Caused by tungsten touching weld metal or parent metal during welding using the TIG welding process
- 26. Copyright © TWI Ltd 2009 Burn Through Causes • Excessiveamperage during welding of root • Excessive root grinding • Improper welding technique Welding Defects
- 27. Copyright © TWI Ltd 2009 Spatter Causes • Excessive arcenergy • Excessive arc length • Damp electrodes • Arc blow Welding Defects
- 28. Copyright © TWI Ltd 2009 Welding Defects Arc Strikes Causes •Electrode straying onto parent metal • Electrode holder with poor insulation • Poor contact of earth clamp
- 29. Copyright © TWI Ltd 2009 Mechanical Damage Chisel Marks ChiselMarks Chisel Marks Pitting Corrosion Grinding Marks Welding Defects
- 30. Copyright © TWI Ltd 2009 Non-alignment of twoabutting edges 2mm Also Known as: Hi Low. Mismatch. or Misalignment Welding Defects
- 31. Copyright © TWI Ltd 2009 Angular distortion. Measure thedistance 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 Welding Defects
- 32. Copyright © TWI Ltd 2009 Linear misalignment measured inmm 3 mm Angular misalignment measured in mm 3mm Excess weld metal height Lowest plate to highest point Linear Angular Excess penetration Lowest plate to highest point Welding Defects
- 33. Copyright © TWI Ltd 2009 CSWIP 3.1 WeldingInspection TWI Training & Examination Services Materials & Inspection Course Reference WIS 5 Course notes section reference 3.0
- 34. Copyright © TWI Ltd 2009 Rolling Imperfections Direction ofrolling Laminations Segregation Cold Laps* MATERIALS INSPECTION
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- 36. Copyright © TWI Ltd 2009 Plate Inspection Size Condition (Corrosion, Mechanicaldamage, Laps, Bands & Laminations) 5L Specification Other checks may need to be made such as: distortion tolerance, number of plates and storage* MATERIALS INSPECTION
- 37. Copyright © TWI Ltd 2009 Pipe Inspection Condition (Corrosion,Damage, Wall thickness Ovality, Laminations & Seam) Specification Welded seam Size LP5 MATERIALS INSPECTION Other checks may need to be made such as: distortion tolerance, number of pipes and storage*
- 38. Copyright © TWI Ltd 2009 Materials Iron Fe Carbon Cis for Strength Manganese Mn is for Toughness Silicon Si < 0.3% Deoxidiser Aluminium Al Grain refiner, <0.008% Deoxidiser + Toughness Chromium Cr Corrosion resistance Molybdenum Mo 1% is for Creep resistance Vanadium V Strength Nickel Ni Low temperature applications Copper Cu Used for weathering steels (Corten) SulphurS Residual element (can cause hot shortness) Phosphorous P Residual element Titanium Ti Grain refiner, Used a a micro alloying element (S&T) Niobium Nb Grain refiner, Used a a micro alloying element (S&T) (S&T) = Strength & Toughness