How to Troubleshoot Apps for the Modern Connected Worker
Welding Inspection Cswip
1. Welding Inspector
Duties and Responsibilities
Section 1
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2. Main Responsibilities 1.1
• Code compliance
• Workmanship control
• Documentation control
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3. Personal Attributes 1.1
Important qualities that good Inspectors are expected to have
are:
• Honesty
Integrity
•
•Knowledge
•Good communicator
Physical fitness
•
• Good eyesight
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4. Standard for Visual Inspection 1.1
Basic Requirements
BS EN 970 - Non-destructive examination of fusion
welds - Visual examination
Welding Inspection Personnel should:
• be familiar with relevant standards, rules and specifications
applicable to the fabrication work to be undertaken
• be informed about the welding procedures to be used
• have good vision (which should be checked every 12
months)
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5. Welding Inspection 1.2
Conditions for Visual Inspection (to BS EN 970)
Illumination:
• 350 lux minimum required
• (recommends 500 lux - normal shop or office lighting)
Vision Access:
• eye should be within 600mm of the surface
• viewing angle (line from eye to surface) to be not less than
30°
600mm
30°
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6. Welding Inspection 1.3
Aids to Visual Inspection (to BS EN 970)
When access is restricted may use:
• a mirrored boroscope
• a fibre optic viewing system
} usually by
agreement
Other aids:
• welding gauges (for checking bevel angles, weld profile, fillet
sizing, undercut depth)
• dedicated weld-gap gauges and linear misalignment (high-low)
gauges
• straight edges and measuring tapes
• magnifying lens (if magnification lens used it should have
magnification between X2 to X5)
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10. Welding Inspection 1.3
Stages of Visual Inspection (to BS EN 970)
Extent of examination and when required should be defined in
the application standard or by agreement between the
contracting parties
For high integrity fabrications inspection required throughout
the fabrication process:
Before welding
(Before assemble & After assembly)
During welding
After welding
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11. Typical Duties of a Welding Inspector 1.5
Before Welding
Preparation:
Familiarisation with relevant „documents‟…
• Application Standard/Code - for visual acceptance
requirements
• Drawings - item details and positions/tolerances etc
• Quality Control Procedures - for activities such as material
handling, documentation control, storage & issue of
welding consumables
• Quality Plan/Inspection & Test Plan/Inspection Checklist -
details of inspection requirements, inspection procedures
& records required
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12. Typical Duties of a Welding Inspector 1.5
Before Welding
Welding Procedures:
• are applicable to joints to be welded & approved
• are available to welders & inspectors
Welder Qualifications:
• list of available qualified welders related to WPS‟s
• certificates are valid and ‘in-date’
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13. Typical Duties of a Welding Inspector 1.5
Before Welding
Equipment:
• all inspection equipment is in good condition & calibrated as
necessary
• all safety requirements are understood & necessary equipment
available
Materials:
• can be identified & related to test certificates, traceability !
• are of correct dimensions
• are in suitable condition (no damage/contamination)
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14. Typical Duties of a Welding Inspector 1.5
Before Welding
Consumables:
• in accordance with WPS’s
• are being controlled in accordance with Procedure
Weld Preparations:
• comply with WPS/drawing
• free from defects & contamination
Welding Equipment:
• in good order & calibrated as required by Procedure
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15. Typical Duties of a Welding Inspector 1.5
Before Welding
Fit-up
• complies with WPS
• Number / size of tack welds to Code / good
workmanship
Pre-heat
• if specified
• minimum temperature complies with WPS
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16. Typical Duties of a Welding Inspector 1.5
During Welding
Weather conditions
• suitable if site / field welding
Welding Process(es)
• in accordance with WPS
Welder
• is approved to weld the joint
Pre-heat (if required)
• minimum temperature as specified by WPS
• maximum interpass temperature as WPS
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17. Typical Duties of a Welding Inspector 1.6
During Welding
Welding consumables
• in accordance with WPS
• in suitable condition
• controlled issue and handling
Welding Parameters
• current, voltage & travel speed – as WPS
Root runs
• if possible, visually inspect root before single-sided welds are
filled up
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18. Typical Duties of a Welding Inspector 1.6
During Welding
Inter-run cleaning
in accordance with an approved method (& back gouging) to
good workmanship standard
Distortion control
• welding is balanced & over-welding is avoided
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19. Typical Duties of a Welding Inspector 1.6
After Welding
Weld Identification
• identified/numbered as required
• is marked with welder‟s identity
Visual Inspection
• ensure weld is suitable for all NDT
• visually inspect & „sentence‟ to Code requirements
Dimensional Survey
• ensure dimensions comply with Code/drawing
Other NDT
• ensure all NDT is completed & reports available
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20. Typical Duties of a Welding Inspector 1.6
After Welding
Repairs
• monitor repairs to ensure compliance with Procedure, ensure
NDT after repairs is completed
• PWHT
• monitor for compliance with Procedure
• check chart records confirm Procedure compliance
Pressure / Load Test
• ensure test equipment is suitably calibrated
• monitor to ensure compliance with Procedure
• ensure all records are available
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21. Typical Duties of a Welding Inspector 1.6
After Welding
Documentation
• ensure any modifications are on ‘as-built’ drawings
• ensure all required documents are available
• Collate / file documents for manufacturing records
• Sign all documentation and forward it to QC department.
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22. Summary of Duties
It is the duty of a Welding Inspector to ensure all the welding and
associated actions are carried out in accordance with the
specification and any applicable procedures.
A Welding Inspector must:
• Observe
To observe all relevant actions related to weld quality throughout
production.
• Record
To record, or log all production inspection points relevant to quality,
including a final report showing all identified imperfections
• Compare
To compare all recorded information with the acceptance criteria
and any other relevant clauses in the applied application standard
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24. Welding Terminology & Definitions 2.1
What is a Weld?
• A localised coalescence of metals or non-metals produced
either by heating the materials to the welding temperature,
with or without the application of pressure, or by the
application of pressure alone (AWS)
• A permanent union between materials caused by heat, and
or pressure (BS499)
• An Autogenous weld:
A weld made with out the use of a filler material and can
only be made by TIG or Oxy-Gas Welding
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25. Welding Terminology & Definitions 2.1
What is a Joint?
• The junction of members or the edges of members that are
to be joined or have been joined (AWS)
• A configuration of members (BS499)
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26. Joint Terminology 2.2
Edge Open & Closed Corner Lap
Tee Butt
Cruciform
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30. Butt Preparations – Sizes 2.4
Partial Penetration Butt Weld
Actual Throat
Design Throat
Thickness
Thickness
Full Penetration Butt Weld
Design Throat Actual Throat
Thickness Thickness
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31. Weld Zone Terminology 2.5
Face
A B
Weld
metal
Heat Weld
Affected Boundary
Zone
C D
Root
A, B, C & D = Weld Toes
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32. Weld Zone Terminology 2.5
Weld cap width
Excess
Cap height Actual Throat Design
or Weld Thickness Throat
Reinforcement Thickness
Excess Root
Penetration
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33. Heat Affected Zone (HAZ) 2.5
Maximum solid solid-liquid Boundary
Temperature weld
grain growth zone
metal
recrystallised zone
partially transformed zone
tempered zone
unaffected base
material
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34. Joint Preparation Terminology 2.7
Included angle Included angle
Angle of
bevel
Root
Radius
Root Face Root Face
Root Gap Root Gap
Single-V Butt Single-U Butt
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35. Joint Preparation Terminology 2.8 & 2.9
Angle of bevel Angle of bevel
Root
Radius
Root Face Root Gap Root Face
Root Gap Land
Single Bevel Butt Single-J Butt
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36. Single Sided Butt Preparations 2.10
Single sided preparations are normally made on thinner materials, or
when access form both sides is restricted
Single Bevel Single Vee
Single-J Single-U
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37. Double Sided Butt Preparations 2.11
Double sided preparations are normally made on thicker materials, or
when access form both sides is unrestricted
Double -Bevel Double -Vee
Double - J Double - U
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38. Weld Preparation
Terminology & Typical Dimensions: V-Joints
bevel angle
included angle
root face
root gap
Typical Dimensions
bevel angle 30 to 35°
root face ~1.5 to ~2.5mm
root gap ~2 to ~4mm
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39. Butt Weld - Toe Blend
6 mm •Most codes quote the weld
toes shall blend smoothly
80 •This statement is not
quantitative and therefore
open to individual
Poor Weld Toe Blend Angle interpretation
3 mm •The higher the toe blend
angle the greater the
20 amount of stress
concentration
•The toe blend angle ideally
Improved Weld Toe Blend
Angle should be between 20o-30o
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40. Fillet Weld Features 2.13
Excess
Weld
Metal
Vertical
Leg
Length Design
Throat
Horizontal leg
Length
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41. Fillet Weld Throat Thickness 2.13
a
b
a = Design Throat Thickness
b = Actual Throat Thickness
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42. Deep Penetration Fillet Weld Features 2.13
a
a = Design Throat Thickness b
b = Actual Throat Thickness
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43. Fillet Weld Sizes 2.14
Calculating Throat Thickness from a known Leg Length:
Design Throat Thickness = Leg Length x 0.7
Question: The Leg length is 14mm.
What is the Design Throat?
Answer: 14mm x 0.7 = 10mm Throat Thickness
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44. Fillet Weld Sizes 2.14
Calculating Leg Length from a known Design Throat
Thickness:
Leg Length = Design Throat Thickness x 1.4
Question: The Design Throat is 10mm.
What is the Leg length?
Answer: 10mm x 1.4 = 14mm Leg Length
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45. Features to Consider 2 2.14
Importance of Fillet Weld Leg Length Size
(a) (b)
8mm
4mm
4mm 2mm
Approximately the same weld volume in both Fillet
Welds, but the effective throat thickness has been
altered, reducing considerably the strength of weld B
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46. Fillet Weld Sizes 2.14
Importance of Fillet weld leg length Size
(a) (b) Excess
Excess
4mm 6mm
(a) (b)
4mm 6mm
Area = 4 x 4 = Area = 6 x 6 =
8mm2 18mm2
2 2
The c.s.a. of (b) is over double the area of (a) without the extra
excess weld metal being added
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47. Fillet Weld Profiles 2.15
Fillet welds - Shape
Mitre Fillet Convex Fillet
A concave profile
is preferred for
joints subjected to
Concave Fillet fatigue loading
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48. Fillet Features to Consider 2.15
EFFECTIVE THROAT THICKNESS
“a” = Nominal throat thickness “s” = Effective throat thickness
a s
Deep penetration fillet welds from high heat
input welding process MAG, FCAW & SAW etc
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51. Welding position designation 2.17
Butt welds in plate (see ISO 6947)
Flat - PA Overhead - PE
Vertical
up - PF
Vertical Horizontal - PC
down - PG
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52. Welding position designation 2.17
Butt welds in pipe (see ISO 6947)
Vertical up - PF Vertical down - PG
Flat - PA axis: horizontal axis: horizontal
axis: horizontal pipe: fixed pipe: fixed
pipe: rotated
H-L045 J-L045 Horizontal - PC
axis: inclined at 45° axis: inclined at 45° axis: vertical
pipe: fixed pipe: fixed pipe: fixed
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53. Welding position designation 2.17
Fillet welds on plate (see ISO 6947)
Flat - PA Horizontal - PB Overhead - PD
Vertical up - PF Vertical down - PG
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54. Welding position designation 2.17
Fillet welds on pipe (see ISO 6947)
Flat - PA Horizontal - PB Overhead - PD
axis: inclined at 45° axis: vertical axis: vertical
pipe: rotated pipe: fixed pipe: fixed
Horizontal - PB Vertical up - PF Vertical down - PG
axis: horizontal axis: horizontal axis: horizontal
pipe: rotated pipe: fixed pipe: fixed
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55. Plate/Fillet Weld Positions 2.17
PA / 1G
PA / 1F
PF / 3G
PB / 2F
PC / 2G
PE / 4G PG / 3G
PD / 4F
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57. Travel Speed Measurement 2.18
Definition: the rate of weld progression
measured in case of mechanised and automatic
welding processes
in case of MMA can be determined using ROL and arc
time
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59. Welding Imperfections 3.1
All welds have imperfections
• Imperfections are classed as defects when they are of a
type, or size, not allowed by the Acceptance Standard
A defect is an unacceptable imperfection
• A weld imperfection may be allowed by one Acceptance
Standard but be classed as a defect by another Standard
and require removal/rectification
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60. Welding Imperfections 3.1
Standards for Welding Imperfections
BS EN ISO 6520-1(1998) Welding and allied processes –
Classification of geometric
imperfections in metallic materials -
Part 1: Fusion welding
Imperfections are classified into 6 groups, namely:
1 Cracks
2 Cavities
3 Solid inclusions
4 Lack of fusion and penetration
5 Imperfect shape and dimensions
6 Miscellaneous imperfections
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61. Welding Imperfections 3.1
Standards for Welding Imperfections
EN ISO 5817 (2003) Welding - Fusion-welded joints in steel,
nickel, titanium and their alloys (beam
welding excluded) - Quality levels for
imperfections
This main imperfections given in EN ISO 6520-1 are listed in
EN ISO 5817 with acceptance criteria at 3 levels, namely
Level B (highest)
Level C (intermediate)
Level D (general)
This Standard is „directly applicable to visual testing of welds‟
...(weld surfaces & macro examination)
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63. Cracks 3.1
Cracks that may occur in welded materials are
caused generally by many factors and may be
classified by shape and position.
Classified by Shape Classified by Position
•Longitudinal •HAZ
•Transverse •Centerline
•Chevron •Crater
•Lamellar Tear •Fusion zone
•Parent metal
Note: Cracks are classed as Planar Defects.
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64. Cracks 3.1
Longitudinal parent metal Transverse weld metal
Longitudinal weld metal
Lamellar tearing
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67. Cracks 3.2
Solidification Cracking
• Occurs during weld solidification process
• Steels with high sulphur impurities content (low ductility
at elevated temperature)
• Requires high tensile stress
• Occur longitudinally down centre of weld
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68. Cracks 3.3
Hydrogen Induced Cold Cracking
• Requires susceptible hard grain structure, stress, low
temperature and hydrogen
• Hydrogen enters weld via welding arc mainly as result of
contaminated electrode or preparation
• Hydrogen diffuses out into parent metal on cooling
• Cracking developing most likely in HAZ
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69. Lamellar Tearing 3.5
• Location: Parent metal
• Steel Type: Any steel type possible
• Susceptible Microstructure: Poor through thickness ductility
• Lamellar tearing has a step like appearance due to the solid
inclusions in the parent material (e.g. sulphides and
silicates) linking up under the influence of welding stresses
• Low ductile materials in the short transverse direction
containing high levels of impurities are very susceptible to
lamellar tearing
• It forms when the welding stresses act in the short
transverse direction of the material (through thickness
direction)
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70. Gas Cavities 3.6
Gas pore Cluster porosity
Causes:
•Loss of gas shield
•Damp electrodes
•Contamination
Blow hole •Arc length too large
Herringbone porosity
•Damaged electrode flux
•Moisture on parent material
•Welding current too low
Gas pore <1.5mm
Root piping Blow hole.>1.6mm
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71. Gas Cavities 3.7
Porosity
Root piping
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72. Gas Cavities 3.8
Cluster porosity Herringbone porosity
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74. Crater Pipe 3.9
Crater pipe is a shrinkage defect and not a gas defect, it has
the appearance of a gas pore in the weld crater
Crater cracks Causes:
(Star cracks)
• Too fast a cooling
rate
• Deoxidization
reactions and
liquid to solid
Crater pipe volume change
• Contamination
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75. Solid Inclusions 3.10
Slag inclusions are defined as a non-metallic inclusion caused
by some welding process
Causes:
•Slag originates from
welding flux
Slag inclusions Lack of sidewall •MAG and TIG welding
fusion with process produce silica
associated slag inclusions
•Slag is caused by
inadequate cleaning
•Other inclusions include
Parallel slag lines Lack of interun tungsten and copper
fusion + slag inclusions from the TIG
and MAG welding process
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77. Welding Imperfections 3.13
Typical Causes of Lack of Fusion:
• welding current too low
• bevel angle too steep
• root face too large (single-sided weld)
• root gap too small (single-sided weld)
• incorrect electrode angle
• linear misalignment
• welding speed too high
• welding process related – particularly dip-transfer GMAW
• flooding the joint with too much weld metal (blocking Out)
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79. Lack of Fusion 3.13
Lack of sidewall fusion + incomplete filled groove
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80. Weld Root Imperfections 3.15
Lack of Root Fusion Lack of Root Penetration
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81. Cap Undercut 3.18
Intermittent Cap Undercut
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82. Undercut 3.18
Root undercut Cap undercut
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83. Surface and Profile 3.19
Incomplete filled groove Poor cap profile
Poor cap profiles and
excessive cap reinforcements
may lead to stress
concentration points at the
weld toes and will also
contribute to overall poor toe
blend Excessive cap height
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84. Surface and Profile 3.19
Excess cap reinforcement Incomplete filled groove
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86. Overlap 3.21
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
Causes:
•Contamination
•Slow travel speed
•Incorrect welding
technique
•Current too low
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87. Overlap 3.21
Toe Overlap
Toe Overlap
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88. Set-Up Irregularities 3.22
Linear misalignment is
measured from the lowest
plate to the highest point.
Plate/pipe Linear Misalignment
(Hi-Lo)
Angular misalignment is
measured in degrees
Angular Misalignment
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91. Incomplete Groove 3.23
Lack of sidewall fusion + incomplete filled groove
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92. Weld Root Imperfections 3.24
A shallow groove, which may occur in the root of a butt weld
Causes:
• Excessive back purge
pressure during TIG welding
Excessive root bead grinding
before the application of the
second pass
Concave Root
welding current too high for
2nd pass overhead welding
root gap too large - excessive
„weaving‟
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95. Weld Root Imperfections 3.25
A localized collapse of the weld pool due to excessive
penetration resulting in a hole in the root run
Causes:
• High Amps/volts
• Small Root face
• Large Root Gap
• Slow Travel
Burn through Speed
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97. Oxidized Root (Root Coking)
Causes:
• Loss or insufficient
back purging gas (TIG)
• Most commonly occurs
when welding stainless
steels
• Purging gases include
argon, helium and
occasionally nitrogen
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98. Miscellaneous Imperfections 3.26
Causes:
• Accidental striking of the
arc onto the parent
material
• Faulty electrode holder
• Poor cable insulation
• Poor return lead
clamping
Arc strike
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99. Miscellaneous Imperfections 3.27
Causes:
• Excessive current
• Damp electrodes
• Contamination
• Incorrect wire feed
speed when welding
with the MAG welding
process
Spatter • Arc blow
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100. Mechanical Damage 3.28
Mechanical damage can be defined as any surface material
damage cause during the manufacturing process.
• Grinding
• Hammering
• Chiselling
• Chipping
• Breaking off welded attachments
(torn surfaces)
• Using needle guns to compress
weld capping runs
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101. Mechanical Damage 3.28
Chipping Marks
Mechanical Damage/Grinding Mark
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103. Qualitative and Quantitative Tests 4.1
The following mechanical tests have units and are termed
quantitative tests to measure Mechanical Properties
• Tensile tests (Transverse Welded Joint, All Weld Metal)
• Toughness testing (Charpy, Izod, CTOD)
• Hardness tests (Brinell, Rockwell, Vickers)
The following mechanical tests have no units and are termed
qualitative tests for assessing joint quality
• Macro testing
• Bend testing
• Fillet weld fracture testing
• Butt weld nick-break testing
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104. Mechanical Test Samples 4.1
Tensile Specimens
CTOD Specimen
Bend Test
Specimen
Charpy Specimen
Fracture Fillet
Specimen
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105. Destructive Testing 4.1
WELDING PROCEDURE QUALIFICATION TESTING
top of fixed pipe
2 Typical Positions for Test
Pieces
Specimen Type Position
•Macro + Hardness 5
3
•Transverse Tensile 2, 4
•Bend Tests 2, 4
•Charpy Impact Tests 3
4 •Additional Tests 3
5
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106. Definitions
Mechanical Properties of metals are related to the amount of
deformation which metals can withstand under different
circumstances of force application.
• Malleability Ability of a material to
withstand deformation
• Ductility
under static compressive
• Toughness loading without rupture
• Hardness
• Tensile Strength
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107. Definitions
Mechanical Properties of metals are related to the amount of
deformation which metals can withstand under different
circumstances of force application.
• Malleability Ability of a material
undergo plastic
• Ductility
deformation under static
• Toughness tensile loading without
• Hardness rupture. Measurable
elongation and reduction
• Tensile Strength in cross section area
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108. Definitions
Mechanical Properties of metals are related to the amount of
deformation which metals can withstand under different
circumstances of force application.
• Malleability Ability of a material to
withstand bending or the
• Ductility
application of shear
• Toughness stresses by impact loading
• Hardness without fracture.
• Tensile Strength
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109. Definitions
Mechanical Properties of metals are related to the amount of
deformation which metals can withstand under different
circumstances of force application.
• Malleability Measurement of a
materials surface
• Ductility
resistance to indentation
• Toughness from another material by
• Hardness static load
• Tensile Strength
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110. Definitions
Mechanical Properties of metals are related to the amount of
deformation which metals can withstand under different
circumstances of force application.
• Malleability Measurement of the
maximum force required to
• Ductility
fracture a materials bar of
• Toughness unit cross-sectional area in
• Hardness tension
• Tensile Strength
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111. Transverse Joint Tensile Test 4.2
Weld on plate
Multiple cross joint
Weld on pipe specimens
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112. Tensile Test 4.3
All-Weld Metal Tensile
Specimen
Transverse Tensile
Specimen
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113. STRA (Short Transverse Reduction Area)
For materials that may be subject to Lamellar Tearing
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115. Charpy V-Notch Impact Test 4.5
Objectives:
• measuring impact strength in different weld joint areas
• assessing resistance toward brittle fracture
Information to be supplied on the test report:
• Material type
• Notch type
• Specimen size
• Test temperature
• Notch location
• Impact Strength Value
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116. Ductile / Brittle Transition Curve 4.6
Ductile fracture
Temperature range
47 Joules
Transition range Ductile/Brittle
transition
point
28 Joules
Energy absorbed
Brittle fracture
- 50 - 40 - 30 - 20 - 10 0
Testing temperature - Degrees Centigrade
Three specimens are normally tested at each temperature
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117. Comparison Charpy Impact Test Results 4.6
Impact Energy Joules
Room Temperature -20oC Temperature
1. 197 Joules 1. 49 Joules
2. 191 Joules 2. 53 Joules
3. 186 Joules 3. 51 Joules
Average = 191 Joules Average = 51 Joules
The test results show the specimens carried out at room
temperature absorb more energy than the specimens carried
out at -20oC
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118. Charpy V-notch impact test specimen 4.7
Specimen dimensions according ASTM E23
ASTM: American Society of Testing Materials
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119. Charpy V-Notch Impact Test 4.8
Specime Pendulu
n m
(striker)
Anvil (support)
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120. Charpy Impact Test 4.9
22.5o
2 mm 10 mm 100% Brittle
Machined
notch
Fracture surface
8 mm
100% bright
crystalline brittle
fracture
100% Ductile
Machined
notch
Large reduction
in area, shear
lips
Randomly torn,
dull gray fracture
surface
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121. Hardness Testing 4.10
Definition
Measurement of resistance of a material against
penetration of an indenter under a constant load
There is a direct correlation between UTS and
hardness
Hardness tests:
Brinell
Vickers
Rockwell
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122. Hardness Testing 4.10
Objectives:
• measuring hardness in different areas of a welded joint
• assessing resistance toward brittle fracture, cold cracking
and corrosion sensitivity within a H2S (Hydrogen Sulphide)
environment.
Information to be supplied on the test report:
• material type
• location of indentation
• type of hardness test and load applied on the indenter
• hardness value
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123. Vickers Hardness Test 4.11
Vickers hardness tests:
indentation body is a square based diamond pyramid
(136º included angle)
the average diagonal (d) of the impression is
converted to a hardness number from a table
it is measured in HV5, HV10 or HV025
Adjustable
Diamond Indentation shutters
indentor
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125. Brinell Hardness Test 4.11
• Hardened steel ball of given diameter is subjected for
a given time to a given load
• Load divided by area of indentation gives Brinell
hardness in kg/mm2
• More suitable for on site hardness testing
30KN
Ø=10mm
steel ball
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126. Rockwell Hardness Test
Rockwell B Rockwell C
1KN
1.5KN
Ø=1.6mm 120 Diamond
steel ball Cone
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127. Hardness Testing 4.12
usually the hardest region
1.5 to 3mm
fusion line
or
fusion HAZ
boundary
Hardness Test Methods Typical Designations
Vickers 240 HV10
Rockwell Rc 22
Brinell 200 BHN-W
Hardness specimens can also be used for CTOD samples
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128. Crack Tip Opening Displacement testing 4.12
• Test is for fracture toughness
• Square bar machined with a notch placed in
the centre.
• Tested below ambient temperature at a
specified temperature.
• Load is applied at either end of the test
specimen in an attempt to open a crack at the
bottom of the notch
• Normally 3 samples
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129. Fatigue Fracture 4.13
Location: Any stress concentration area
Steel Type: All steel types
Susceptible Microstructure: All grain structures
Test for Fracture Toughness is CTOD
(Crack Tip Opening Displacement)
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130. Fatigue Fracture 4.13
• Fatigue cracks occur under cyclic stress conditions
• Fracture normally occurs at a change in section, notch
and weld defects i.e stress concentration area
• All materials are susceptible to fatigue cracking
• Fatigue cracking starts at a specific point referred to as
a initiation point
• The fracture surface is smooth in appearance
sometimes displaying beach markings
• The final mode of failure may be brittle or ductile or a
combination of both
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131. Fatigue Fracture
Precautions against Fatigue Cracks
• Toe grinding, profile grinding.
• The elimination of poor profiles
• The elimination of partial penetration welds and weld
defects
• Operating conditions under the materials endurance limits
• The elimination of notch effects e.g. mechanical damage
cap/root undercut
• The selection of the correct material for the service
conditions of the component
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132. Fatigue Fracture
Fatigue fracture occurs in structures subject to repeated
application of tensile stress.
Crack growth is slow (in same cases, crack may grow into an
area of low stress and stop without failure).
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133. Fatigue Fracture
Secondary mode of failure Fatigue fracture surface
ductile fracture rough fibrous
appearance smooth in appearance
Initiation points / weld defects
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134. Fatigue Fracture
Fatigue fracture distinguish features:
• Crack growth is slow
• It initiate from stress concentration points
• load is considerably below the design or yield stress level
• The surface is smooth
• The surface is bounded by a curve
• Bands may sometimes be seen on the smooth surface –”beachmarks”.
They show the progress of the crack front from the point of origin
• The surface is 90° to the load
• Final fracture will usually take the form of gross yielding (as the
maximum stress in the remaining ligament increase!)
• Fatigue crack need initiation + propagation periods
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135. Bend Tests 4.15
Object of test:
• To determine the soundness of the weld zone. Bend
testing can also be used to give an assessment of
weld zone ductility.
• There are three ways to perform a bend test:
Face bend
Root bend Side bend
Side bend tests are normally carried out on welds over 12mm in thickness
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136. Bending test 4.16
Types of bend test for welds (acc. BS EN 910):
“t” up to 12 mm Root / face
bend
Thickness of material - “t”
“t” over 12 mm Side bend
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137. Fillet Weld Fracture Tests 4.17
Object of test:
• To break open the joint through the weld to permit
examination of the fracture surfaces
• Specimens are cut to the required length
• A saw cut approximately 2mm in depth is applied along
the fillet welds length
• Fracture is usually made by striking the specimen with a
single hammer blow
• Visual inspection for defects
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138. Fillet Weld Fracture Tests 4.17
Hammer
2mm
Notch
Fracture should break weld saw cut to root
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139. Fillet Weld Fracture Tests 4.17
This fracture indicates This fracture has
lack of fusion occurred saw cut to root
Lack of Penetration
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140. Nick-Break Test 4.18
Object of test:
• To permit evaluation of any weld defects across the
fracture surface of a butt weld.
• Specimens are cut transverse to the weld
• A saw cut approximately 2mm in depth is applied along the
welds root and cap
• Fracture is usually made by striking the specimen with a
single hammer blow
• Visual inspection for defects
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141. Nick-Break Test 4.18
Notch cut by hacksaw
2 mm
19 mm
2 mm
Approximately 230 mm
Weld reinforcement
may or may not be
removed
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142. Nick Break Test 4.18
Alternative nick-break test
specimen, notch applied all
way around the specimen
Lack of root penetration Inclusions on fracture
or fusion line
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143. Summary of Mechanical Testing 4.19
We test welds to establish minimum levels of mechanical
properties, and soundness of the welded joint
We divide tests into Qualitative & Quantitative methods:
Quantitative: (Have units/numbers) Qualitative: (Have no units/numbers)
To measure mechanical properties For assessing joint quality
Hardness (VPN & BHN) Macro tests
Toughness (Joules & ft.lbs) Bend tests
Strength (N/mm2 & PSI, MPa) Fillet weld fracture tests
Ductility / Elongation (E%) Butt Nick break tests
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145. Welding Procedure Qualification 5.1
Question:
What is the main reason for carrying out a Welding Procedure
Qualification Test ?
(What is the test trying to show ?)
Answer:
To show that the welded joint has the properties* that satisfy
the design requirements (fit for purpose)
* properties
•mechanical properties are the main interest - always strength but
toughness & hardness may be important for some applications
•test also demonstrates that the weld can be made without defects
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146. Welding Procedures 5.1
Producing a welding procedure involves:
• Planning the tasks
• Collecting the data
• Writing a procedure for use of for trial
• Making a test welds
• Evaluating the results
• Approving the procedure
• Preparing the documentation
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147. Welding Procedures 5.2
In most codes reference is made to how the procedure are to
be devised and whether approval of these procedures is
required.
The approach used for procedure approval depends on the
code:
Example codes:
• AWS D.1.1: Structural Steel Welding Code
• BS 2633: Class 1 welding of Steel Pipe Work
• API 1104: Welding of Pipelines
• BS 4515: Welding of Pipelines over 7 Bar
Other codes may not specifically deal with the requirement of
a procedure but may contain information that may be used in
writing a weld procedure
• EN 1011Process of Arc Welding Steels
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148. Welding Procedure Qualification 5.3
(according to EN ISO 15614)
The welding engineer writes qualified Welding Procedure
Specifications (WPS) for production welding
Production welding conditions must remain within the range of
qualification allowed by the WPQR
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149. Welding Procedure Qualification 5.3
(according to EN Standards)
welding conditions are called welding variables
welding variables are classified by the EN ISO Standard as:
•Essential variables
•Non-essential variables
•Additional variables
Note: additional variables = ASME supplementary essential
The range of qualification for production welding is based on
the limits that the EN ISO Standard specifies for essential
variables*
(* and when applicable - the additional variables)
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150. Welding Procedure Qualification 5.3
(according to EN Standards)
WELDING ESSENTIAL VARIABLES
Question:
Why are some welding variables classified as essential ?
Answer:
A variable, that if changed beyond certain limits (specified by
the Welding Standard) may have a significant effect on the
properties* of the joint
* particularly joint strength and ductility
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151. Welding Procedure Qualification 5.3
(according to EN Standards)
SOME TYPICAL ESSENTIAL VARIABLES
• Welding Process
• Post Weld Heat Treatment (PWHT)
• Material Type
• Electrode Type, Filler Wire Type (Classification)
• Material Thickness
• Polarity (AC, DC+ve / DC-ve)
• Pre-Heat Temperature
• Heat Input
• Welding Position
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152. Welding Procedures 5.3
Components of a welding procedure
Parent material
• Type (Grouping)
• Thickness
• Diameter (Pipes)
• Surface condition)
Welding process
• Type of process (MMA, MAG, TIG, SAW etc)
• Equipment parameters
• Amps, Volts, Travel speed
Welding Consumables
• Type of consumable/diameter of consumable
• Brand/classification
• Heat treatments/ storage
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153. Welding Procedures 5.3
Components of a welding procedure
Joint design
•Edge preparation
•Root gap, root face
•Jigging and tacking
•Type of baking
Welding Position
•Location, shop or site
•Welding position e.g. 1G, 2G, 3G etc
•Any weather precaution
Thermal heat treatments
•Preheat, temps
•Post weld heat treatments e.g. stress relieving
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154. Welding Procedures 5.3
Object of a welding procedure test
To give maximum confidence that the welds mechanical
and metallurgical properties meet the requirements of the
applicable code/specification.
Each welding procedure will show a range to which the
procedure is approved (extent of approval)
If a customer queries the approval evidence can be
supplied to prove its validity
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156. Example:
Welding
Procedure
Specification
(WPS)
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157. Welder Qualification 5.4
Numerous codes and standards deal with welder qualification,
e.g. BS EN 287.
• Once the content of the procedure is approved the next
stage is to approve the welders to the approved procedure.
• A welders test know as a Welders Qualification Test (WQT).
Object of a welding qualification test:
• To give maximum confidence that the welder meets the
quality requirements of the approved procedure (WPS).
• The test weld should be carried out on the same material and
same conditions as for the production welds.
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158. Welder Qualification 5.4 & 5.5
(according to EN Standards)
Question:
What is the main reason for qualifying a welder ?
Answer:
To show that he has the skill to be able to make production
welds that are free from defects
Note: when welding in accordance with a Qualified WPS
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159. Welder Qualification
(according to EN 287 )
5.5
The welder is allowed to make production welds within the
range of qualification shown on the Certificate
The range of qualification allowed for production welding is
based on the limits that the EN Standard specifies for the
welder qualification essential variables
A Certificate may be withdrawn by the Employer if there is
reason to doubt the ability of the welder, for example
• a high repair rate
• not working in accordance with a qualified WPS
The qualification shall remain valid for 2 years provided there is certified
confirmation of welding to the WPS in that time.
A Welder‟s Qualification Certificate automatically expires if the welder has not
used the welding process for 6 months or longer.
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160. Welding Procedure Qualification 5.7
(according to EN ISO 15614)
Welding Engineer writes a preliminary Welding Procedure
Specification (pWPS) for each test weld to be made
• A welder makes a test weld in accordance with the pWPS
• A welding inspector records all the welding conditions used
for the test weld (referred to as the „as-run‟ conditions)
An Independent Examiner/ Examining Body/ Third Party
inspector may be requested to monitor the qualification
process
The finished test weld is subjected to NDT in accordance with
the methods specified by the EN ISO Standard - Visual, MT or
PT & RT or UT
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161. Welding Procedure Qualification 5.7
(according to EN ISO 15614)
Test weld is subjected to destructive testing (tensile, bend,
macro)
The Application Standard, or Client, may require additional
tests such as impact tests, hardness tests (and for some
materials - corrosion tests)
A Welding Procedure Qualification Record (WPQR) is prepared
giving details of: -
• The welding conditions used for the test weld
• Results of the NDT
• Results of the destructive tests
• The welding conditions that the test weld allows for
production welding
The Third Party may be requested to sign the WPQR as a true
record
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162. Welder Qualification 5.9
(according to EN 287 )
An approved WPS should be available covering the range of
qualification required for the welder approval.
• The welder qualifies in accordance with an approved WPS
• A welding inspector monitors the welding to make sure that the
welder uses the conditions specified by the WPS
EN Welding Standard states that an Independent Examiner,
Examining Body or Third Party Inspector may be required to
monitor the qualification process
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163. Welder Qualification 5.9
(according to EN 287 )
The finished test weld is subjected to NDT by the methods
specified by the EN Standard - Visual, MT or PT & RT or UT
The test weld may need to be destructively tested - for certain
materials and/or welding processes specified by the EN
Standard or the Client Specification
• A Welder‟s Qualification Certificate is prepared showing the
conditions used for the test weld and the range of qualification
allowed by the EN Standard for production welding
• The Qualification Certificate is usually endorsed by a Third
Party Inspector as a true record of the test
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164. Welder Qualification 5.10
Information that should be included on a welders test certificate are,
which the welder should have or have access to a copy of !
• Welders name and identification number
• Date of test and expiry date of certificate
• Standard/code e.g. BS EN 287
• Test piece details
• Welding process.
• Welding parameters, amps, volts
• Consumables, flux type and filler classification details
• Sketch of run sequence
• Welding positions
• Joint configuration details
• Material type qualified, pipe diameter etc
• Test results, remarks
• Test location and witnessed by
• Extent (range) of approval
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166. Material Inspection
One of the most important items to consider is Traceability.
The materials are of little use if we can not, by use of an effective QA
system trace them from specification and purchase order to final
documentation package handed over to the Client.
All materials arriving on site should be inspected for:
• Size / dimensions
• Condition
• Type / specification
In addition other elements may need to be considered depending on
the materials form or shape
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167. Pipe Inspection
We inspect the condition
(Corrosion, Damage, Wall thickness Ovality, Laminations & Seam)
Specification LP5
Welded Size
seam
Other checks may need to be made such as: distortion tolerance,
number of plates and storage.
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168. Plate Inspection
We inspect the condition
(Corrosion, Mechanical damage, Laps, Bands &
Laminations)
Specification
5L
Size
Other checks may need to be made such as: distortion
tolerance, number of plates and storage.
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169. Parent Material Imperfections
Mechanical damage Lap
Lamination
Segregation line
Laminations are caused in the parent plate by the steel making
process, originating from ingot casting defects.
Segregation bands occur in the centre of the plate and are low
melting point impurities such as sulphur and phosphorous.
Laps are caused during rolling when overlapping metal does not
fuse to the base material.
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174. Codes & Standards
The 3 agencies generally identified in a code or standard:
The customer, or client
The manufacturer, or contractor
The 3rd party inspection, or clients representative
Codes often do not contain all relevant data, but may
refer to other standards
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177. Weld symbols on drawings
Advantages of symbolic representation:
• simple and quick plotting on the drawing
• does not over-burden the drawing
• no need for additional view
• gives all necessary indications regarding the specific joint to
be obtained
Disadvantages of symbolic representation:
• used only for usual joints
• requires training for properly understanding of symbols
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178. Weld symbols on drawings
The symbolic representation includes:
• an arrow line
• a reference line
• an elementary symbol
The elementary symbol may be completed by:
• a supplementary symbol
• a means of showing dimensions
• some complementary indications
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179. Dimensions
Convention of dimensions
In most standards the cross sectional dimensions are given to
the left side of the symbol, and all linear dimensions are give on
the right side
BS EN ISO 22553
a = Design throat thickness
s = Depth of Penetration, Throat thickness
z = Leg length (min material thickness)
AWS A2.4
•In a fillet weld, the size of the weld is the leg length
•In a butt weld, the size of the weld is based on the depth of the
joint preparation
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180. Weld symbols on drawings
A method of transferring information from the
design office to the workshop is:
Please weld
here
The above information does not tell us much about the wishes
of the designer. We obviously need some sort of code which
would be understood by everyone.
Most countries have their own standards for symbols.
Some of them are AWS A2.4 & BS EN 22553 (ISO 2553)
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181. Weld symbols on drawings
Joints in drawings may be indicated:
•by detailed sketches, showing every dimension
•by symbolic representation
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182. Elementary Welding Symbols
(BS EN ISO 22553 & AWS A2.4)
Convention of the elementary symbols:
Various categories of joints are characterised by an elementary symbol.
The vertical line in the symbols for a fillet weld, single/double bevel butts
and a J-butt welds must always be on the left side.
Weld type Sketch Symbol
Square edge
butt weld
Single-v
butt weld
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183. Elementary Welding Symbols
Weld type Sketch Symbol
Single-V butt
weld with broad
root face
Single
bevel butt
weld
Single bevel
butt weld with
broad root
face
Backing run
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184. Elementary Welding Symbols
Weld type Sketch Symbol
Single-U
butt weld
Single-J
butt weld
Surfacing
Fillet weld
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185. ISO 2553 / BS EN 22553
Plug weld Square Butt weld
Resistance spot weld Steep flanked
Single-V Butt
Resistance seam weld Surfacing
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186. Arrow Line
(BS EN ISO 22553 & AWS A2.4):
Convention of the arrow line:
• Shall touch the joint intersection
• Shall not be parallel to the drawing
• Shall point towards a single plate preparation (when only
one plate has preparation)
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187. Reference Line
(AWS A2.4)
Convention of the reference line:
Shall touch the arrow line
Shall be parallel to the bottom of the drawing
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188. Reference Line
(BS EN ISO 22553)
Convention of the reference line:
• Shall touch the arrow line
• Shall be parallel to the bottom of the drawing
• There shall be a further broken identification line above or
beneath the reference line (Not necessary where the weld
is symmetrical!)
or
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189. Double side weld symbols
(BS EN ISO 22553 & AWS A2.4)
Convention of the double side weld symbols:
Representation of welds done from both sides of the joint
intersection, touched by the arrow head
Fillet weld Double bevel Double J
Double V Double U
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190. ISO 2553 / BS EN 22553
Reference lines
Arrow line
Other side Arrow side
Arrow side Other side
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191. ISO 2553 / BS EN 22553
MR
M
Single-V Butt with Single-U Butt with
permanent backing strip removable backing strip
Single-V Butt flush cap Single-U Butt with sealing run
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192. ISO 2553 / BS EN 22553
Single-bevel butt Double-bevel butt
Single-bevel butt Single-J butt
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193. ISO 2553 / BS EN 22553
s10
10
15
Partial penetration single-V butt
„S‟ indicates the depth of penetration
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194. ISO 2553 / BS EN 22553
a = Design throat thickness
s = Depth of Penetration, Throat
thickness
z = Leg length(min material thickness)
a = (0.7 x z)
a4
a
z s 4mm Design throat
z6
s6
6mm leg 6mm Actual throat
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195. ISO 2553 / BS EN 22553
Arrow side
Arrow side
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196. ISO 2553 / BS EN 22553
s6
6mm fillet weld
Other side
s6
Other side
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197. ISO 2553 / BS EN 22553
n = number of weld elements
l = length of each weld element
(e) = distance between each weld element
n x l (e)
Welds to be
staggered
2 x 40 (50)
111
3 x 40 (50)
Process
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198. ISO 2553 / BS EN 22553
All dimensions in mm
z5 3 x 80 (90)
z6 3 x 80 (90)
5
80 80 80
5
6 90 90 90
6
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199. ISO 2553 / BS EN 22553
All dimensions in mm
z8 3 x 80 (90)
z6 3 x 80 (90)
6
80 80 80
6
8 90 90
90
8
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200. Supplementary symbols
(BS EN ISO 22553 & AWS A2.4)
Convention of supplementary symbols
Supplementary information such as welding process, weld
profile, NDT and any special instructions
Toes to be ground smoothly
(BS EN only)
Site Weld
Concave or Convex
Weld all round
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201. Supplementary symbols
(BS EN ISO 22553 & AWS A2.4)
Convention of supplementary symbols
Supplementary information such as welding process, weld profile,
NDT and any special instructions
Ground flush
111
MR M
Removable Permanent Welding process
backing strip backing strip numerical BS EN
Further supplementary information, such as WPS number, or
NDT may be placed in the fish tail
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202. ISO 2553 / BS EN 22553
a b
c d
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203. ISO 2553 / BS EN 22553
Mitre Convex
Toes
Concave
shall be
blended
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204. ISO 2553 / BS EN 22553
a = Design throat thickness
s = Depth of Penetration, Throat
thickness
z = Leg length(min material thickness)
a = (0.7 x z)
a4
a
z s 4mm Design throat
z6
s6
6mm leg 6mm Actual throat
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205. ISO 2553 / BS EN 22553
Complimentary Symbols
Field weld (site weld) Welding to be carried out
all round component
(peripheral weld)
NDT WPS
The component requires Additional information,
NDT inspection the reference document
is included in the box
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206. ISO 2553 / BS EN 22553
Numerical Values for Welding Processes:
111: MMA welding with covered electrode
121: Sub-arc welding with wire electrode
131: MIG welding with inert gas shield
135: MAG welding with non-inert gas shield
136: Flux core arc welding
141: TIG welding
311: Oxy-acetylene welding
72: Electro-slag welding
15: Plasma arc welding
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