The document discusses various common weld discontinuities and defects such as gas pores, slag inclusions, incomplete penetration, lack of fusion, cracks, and undercut. It describes the causes of these defects which can include trapped gas during solidification, contaminated base metal, improper welding parameters, and faulty joint preparation. Remedies suggested to avoid defects are ensuring adequate shielding from wind, using clean electrodes, maintaining the proper arc length, travel speed, and current level.

1. Common Weld Discontinuities

2. Common Weld Discontinuities

3. Gas Pore
Gas pore
A cavity, generally formed by
trapped gas during the
solidification of molten metal
Cluster Porosity
A group of gas pores

4. Porosity

5. Crater Pipe (GTAW)
AMIT PAHUJA QA
QC NDE WELDING at SADARA

6. Crater Pipe
Crater pipe
A depression due to shrinkage at the end
of a run where the source of heat was
removed. Crater pipes may also lead to micro-cracking
AMIT PAHUJA
Welding Engineering at SADARA

7. Porosity

8. Causes of Porosity
 Insufficient Protection/wind/Tent
 Insufficient interpass cleaning
 Unsteady travel speed
 Welding weave too wide
 Allowing slag to run ahead of the arc
 Using too large and electrode
 Damp electrode

9. Slag Inclusions

10. Causes of Slag
Inclusions
 Base Metal contaminated
 Wet, unclean electrodes
 Insufficient or damp shielding gas
 Excessive arc length
 Welding current too high
 Weld speed too fast

11. Incomplete Penetration

12. Root Defects
Incomplete root penetration
Failure of weld metal to extend into the root of a joint
Lack of root fusion
Lack of union at the root of a joint
Excess penetration bead
Excess weld metal protruding through the root of
a fusion weld made from one side only

13. Causes of Incomplete
Penetration
 Too small a root opening
 Too large a root face
 Excessive high low
 Travel speed too fast
 Welding current too low
 Electrode diameter too large
 Excessive arc length

14. Causes of Excessive Penetration
 Too large a root opening
 Too small a root face
 Welding current too high
 Travel speed too low
 Arc length too short

15. Incomplete Fusion
Lack of Inter Run Fusion

16. Causes of Incomplete Fusion
 Improper electrode angle
 Travel speed too fast
 Welding current too low
 Faulty joint preparation
 Electrode diameter too large

17. Heat Affected Zone

18. Causes of Cracks
 Base metal contaminated
 Excessive joint restraint
 Incorrect pre-heat
 Incorrect filler metal
 Too fast a cooling rate

19. Causes of Undercut
 Incorrect electrode
manipulation
 Welding current too high
 Excessive arc length
 Travel speed too fast

20. Tungsten Inclusions

21. Causes of Tungsten
Inclusions
 Contact of electrode tip with weld pool
 Contact of filler metal with tip of electrode
 Contamination of electrode
 Exceeding current limit for the electrode
 Splits or cracks in tungsten electrode

22. Visual Inspection of Welds

23. Overlap Good Fillet Weld
Overlap
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

24. Arc Strike
Stray flash/arc burn/arc strike
(stray arcing)
1. The damage on the parent material resulting from the accidental striking of
. an arc away from the weld
2. The accidental striking of an arc away from the weld

25. Spatters

26. Effect of Current, Speed, Arc-length

28. Weld Width
Weld width and consistency of weld width
For butt welds and fillet welds,
consider:

29. Butt Weld Size
a) excess weld metal height
b) root penetration
c) weld width
d) root bead width

30. Shape (Butt Welds)
Consider:
Ideally, (a) is the most desirable

31. Bulbous Contour
Bulbous contour
poor appearance

32. Contour Defects
Incompletely filled groove
A continuous or intermittent
channel in the surface of a weld,
running along its length, due to
insufficient weld metal. The
channel may be along the centre or
along one or both edges of the weld

33. Root Defects
Root concavity (suck-back;)
A shallow groove which may occur in the root of
a butt weld, but full fusion is evident
Shrinkage groove
A shallow groove caused by contraction in the
metal along each side of a penetration bead or
along the weld centreline
Burnthrough
(melt through)
A localised collapse of the molten pool due
to excessive penetration, resulting in a hole in
the weld run

34. Toe Blend (Butt Welds)
For butt welds, consider:
In normal practice, (a) is the
most desirable but, again, in
many instances it is difficult to
achieve.
Depending on the service conditions
of the product, the toe blend may be
of greater importance than the size
and shape of the weld. A poor toe
blend may reduce service life by a
considerable margin if the product is
under a cyclic load.

35. Toe Blend (Fillet Welds)
For fillet welds,
consider:
In normal practice, (a) is the
most desirable but, again,
in many instances it is difficult
to achieve. Acceptance levels,
therefore, allow tolerances on
weld shape.

36. Perfect Weld Bead Appearance
SMAW/GTAW

37. Perfect Weld Bead Appearance Fillet
Weld

38. Good Weld Bead Finish GTAW/SMAW

43. Thank You