This document provides information on visual welding inspection for butt and fillet welds. It covers terminology used in welding inspection, types of joint preparation and welds, welding positions, weld features to examine, common weld defects to identify, and the responsibilities and procedures of a welding inspector. The duties of a welding inspector include checking welding procedures, materials, and equipment before welding; monitoring the welding process; and performing visual and non-destructive testing after welding is complete. Key steps in a visual welding inspection are identifying applicable codes and standards, and examining weld size, profile, contours, roots, and surfaces for any defects.

1. Visual Welding Inspector
Part 1
Course Reference D 73
TWI

2. CSWIP Examination Requirements
TWI
# Butt Weld Inspection
Code reference : CSWIP PH6/WI/00
Time Given : 1 Hour 30 minutes
# Fillet Weld Inspection
Code reference : ISO 5817 ( Level D)
Time Given : 1 Hour 15 minutes

3. Terminology
Butt Joints
• Square Edged, Open and Closed
• Single Vee, Butt and Bevel
• Double Vee, Butt and Bevel

4. Terminology Joint Types
Edge Corner Lap
Tee
Cruciform
TWI

5. Terminology Joint Welds
Compound Fillet Butt
Edge Spot Plug
TWI

6. Types of Joint Preparation
Included angle
Root Gap
Root Face
Angle of
bevel
Root Face
Root Gap
Included angle
Root
Radius
Single -V Butt Single - U Butt
TWI

7. Types of Joint Preparation
Root Gap
Root Face Root Face
Root Gap
Root
Radius
Single Bevel Butt Single J Butt
Angle of
bevel
Angle of
bevel
Land
TWI

8. Weld Zone Terminology
Weld zone
Weld metal Heat affected
zone
Root
Fusion zone Weld Junction
TWI

9. Butt Weld Features
Weld cap width
Excess weld metal
Excess root penetration Root bead width
TWI

10. Fillet Weld Features
Horizontal leg length
Vertical
leg
length
Design throat
thickness
TWI

11. Fillet Weld Features
a = Design/ Nominal throat thickness
TWI
a
b
b = Actual throat thickness

12. Fillet Weld Profiles
Mitre fillet
Concave fillet
Convex fillet
TWI

13. Welding Positions
Flat position
UK (USA) 1G rotated
ISO/EN PA
UK (USA): 1G
ISO/EN: PA
UK (USA) 2G Fixed
ISO/EN PC
UK (USA): 2G
ISO/EN: PC
vertical
position
TWI

14. Welding Positions
Vertical
down
UK (USA) 3G
ISO/EN PG
UK (USA) 3G
ISO/EN PF
Vertical
up
UK (USA) 4G
ISO/EN PE
Overhead Position
UK (USA) 5G
ISO/EN PF, PG
Vertical Position
Pipe fixed Horizontal
TWI

15. Welding Positions
45o
Inclined position fixed
UK (USA) 6G
EN/ISO H-LO45
Inclined position Rotated
UK (USA) 1FR
EN/ISO L 45/PA
45o
TWI

16. Terminology
Butt Weld Features
1
2
3 4
5
6
7
8
9
10

17. Terminology
Fillet Weld Features
1
3
5
6
7
8
10
2
9
4

18. Visual Inspection Procedures
• What is the nature of the product?
• What operating conditions will be
present?
• What is the quality of welding required?
• Is there a code or standard available to
inspect the welds to?

19. Main Responsibilities
Code compliance
Workmanship control
Documentation control
TWI

20. Personal Attributes
Honesty
Integrity
Knowledgeable
Good communicator
Physically fit.
TWI

21. Duties of a Welding Inspector
Before Welding.
before assembly.
after assembly.
During welding.
After welding.
TWI

22. Welding Checklist
• Familirization to the relevant code and specification
• Check welding equipment and calibration certificates
• Material identification,size,type and condition
• Consumables type,size,condition,storage and handling
• Review/witness WPS and PQR test and record
• Joint preparation( check)
• Welder qualification test( Review/witness)
• Welding process involved
• Check pre-heating before welding ( if required)
Before Welding Commences

23. Welding Checklist
• Check weather condition
• Check clearance for welding/welder
• Check welder identification for weld
• Check consumables as per WPS used
• Check welding parameters as per WPS used
• Check distortion control
• Check interpass cleaning
• Check run out length ( travel speed)
• Check interpass temperature
• Check usage of line up clamps
• Maintain daily log book
During Welding

24. Welding Checklist
• Perform visual inspection
• Weld and welder identification ( check)
• Post weld heat treatment ( if required)
• Non-destructive Testing ( witness)
• Acceptance standards of NDT
• Repairs (if any)
• Dimensional check ( as per drawing)
• Document control - welding reports etc
Welding Completion

25. Welding Checklist
• Authorization for repair
• Removal and preparation for repair
• Testing of repair - visual and NDT
In the event of repair

26. How Do I Carry Out a Visual
Inspection?
• What is the nature of the product?
• What operating conditions will be
present?
• What is the quality of welding required?
• Is there a code or standard available to
inspect the welds against

27. Features to Consider
Butt welds - Size
Excess weld
metal height
Root penetration
Root bead width
Weld cap width

28. Features to Consider
Fillet welds - Size
Minimum and
maximum leg
length size
Minimum design
throat thickness

29. Features to Consider
Butt welds - Profile

30. Features to Consider
Fillet welds - Size

31. Features to Consider
Butt welds - Toe Blend

32. Features to Consider
Fillet welds - Toe Blend

33. Features to Consider
Butt welds - Weld Width

34. Weld Defects
Defects which may be detected by visual
inspection can be grouped under five headings
Cracks
Surface irregularities
Contour defects
Root defects
Miscellaneous
TWI

35. Weld Defects
Other associated defects
Cavities
Solid inclusions
Set up irregularities
Parent material defects
TWI

36. Cracks
Hydrogen (HICC)
Solidification (Hot tears)
Reheat cracks
Lamellar tearing
The four essential crack mechanisms
TWI

37. Welding Defects
Classified by Shape
• Longitudinal
• Transverse
• Branched
• Chevron
Cracks
Classified by Position
• HAZ
• Centreline
• Crater
• Fusion zone
• Parent metal

38. Cracks
Longitudinal parent metal crack Transverse weld metal crack
Longitudinal weld metal crack Lamellar tearing
TWI

39. Welding Defects
Solidification
• Occurs during weld solidification process
• Steels with high sulphur content (low
ductility at elevated temperature)
• Requires high tensile stress
• Occur longitudinally down centre of weld
• eg Crater cracking
Cracks

40. Welding Defects
Hydrogen Induced
• Requires susceptible grain structure, stress
and hydrogen
• Hydrogen enters via welding arc
• Hydrogen source - atmosphere or
contamination of preparation or electrode
• Moisture diffuses out into parent metal on
cooling
• Most likely in HAZ
Cracks

41. Welding Defects
Lamellar Tearing
• Step like appearance
• Occurs in parent material or HAZ
• Only in rolled direction of the parent material
• Associated with restrained joints subjected to
through thickness stresses on corners, tees
and fillets
• Requires high sulphur or non-metallic
inclusions
Cracks

42. Welding Defects
Re-Heat Cracking
• Occurs mainly in HAZ of low alloy steels
during post weld heat treatment or service at
elevated temperatures
• Occurs in areas of high stress and existing
defects
• Prevented by toe grinding, elimination of poor
profile material selection and controlled post
weld heat treatment
Cracks

43. Surface irregularities

44. Undercut
An irregular groove at the toe of a weld run in
the parent metal
 Excessive amps/volts
 Excessive travel speed
 Incorrect electrode angle
 Excessive weaving
 Incorrect welding technique
 Electrode too large
TWI

45. 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
Contamination
Slow travel speed
Incorrect welding
technique
Current too high
TWI

46. Crater Pipe
Depression at the end of a weld that has a insufficient
cross section.
 Too fast a cooling rate
 Deoxidization
reactions and liquid to
solid volume change
 Contamination
TWI
Crater crack

47. Contour Defects
Incomplete filled groove Poor cap profile
Excessive cap height
TWI
Incomplete filled groove
+ Lack of sidewall fusion

48. Root Defects
Incomplete root fusion
Incomplete root penetration
 Low Amps/volts
 Large Root face
 Small Root Gap
 Fast Travel Speed
 Incorrect Electrode
Angle
 Contamination
TWI

49. Concave root
Root Defects
TWI
 Root faces too large
 Root gap too large
 Excessive back purge
pressure during TIG welding
 Excessive root bead grinding
before the application of the
second pass
A shallow groove, which may occur in the root of a butt weld

50. Shrinkage groove
Root Defects
TWI
 Insufficient weld metal
deposited in the root
pass
 Too fast a cooling rate
during the application of
the root bead pass
 Poor welding technique
A shallow groove caused by contraction in the weld
metal along each side of the penetration bead

51. Root Defects
Burn through
 High Amps/volts
 Small Root face
 Large Root Gap
 Slow Travel Speed
TWI
A localized collapse of the weld pool due to excessive
penetration resulting in a hole in the root run

52. Miscellaneous Defects
Arc strike
 Accidental striking of
the arc onto the parent
material
 Faulty electrode holder
 Poor cable insulation
 Poor return lead
clamping
TWI

53. Spatter
 Excessive current
 Damp electrodes
 Contamination
 Incorrect wire feed
speed when welding
with the MAG welding
process
TWI
Miscellaneous Defects

54. TWI
Gas Cavities
Cluster porosity
Gas pore
Blow hole
Herringbone porosity
Root piping
 Loss of gas shield
 Damp electrodes
 Contamination
 Arc length too large
 Damaged electrode flux
 Moisture on parent
material
 Welding current to low

55. TWI
Solid Inclusions
 Slag originates from welding
flux
 MAG and TIG welding
process produce silica
inclusions
 Slag is caused by
inadequate cleaning
 Other inclusions include
tungsten and copper
inclusions from the TIG and
MAG welding process
Lack of sidewall
fusion with
associated slag
Slag inclusions
Parallel slag lines
Slag inclusions are defined as a non-metallic inclusion
caused by some welding process

56. TWI
Set-up Irregularities
Linear Misalignment
(Hi-Lo)
Poor fit-up
Angular Misalignment

57. TWI
Parent Material Defects
A welding inspector should also inspect the parent
material for any visible defects
Lamination
Mechanical damage Lap
Segregation line