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Welding and inspection
• Presented to the people in need
Course on
WELDING AND INSPECTION
Presentation on “Welding fundamentals,application , Symbol,inspection
An Overview”
by
Chennai
Introduction
• Trainer’s background info …• 15Years in Welding Inspection by Visual and
NDT• Heavy Equipment Fabrication Construction
equipment• Trainer in Manufacturing Quality, QMS, • Six sigma Green Belt, TPM Facilitator, Quality
Circle Team Leader, Welding Quality, NDT Ultrasonic testing and Quality concept.
WELDING THEORY
• “… Welding is joining two pieces of materials.
• Solid+solid Welding = Solid state bonding
• Liquid+Liquid welding=Fusion Welding
• Solid+Liquid Welding=Braze Welding
• Oxy-Aceteline=Gas Welding
• Thermit =
• Atomic hydrogen=
ELECTRICAL ENERGY WELDING
A) ELECTRICAL ARC WELDING
• FCAW -Flux cored Arc Welding
• CAW -Carbon arc Welding
• SMAW -Shielded metal arc Welding
• GMAW -Gas metal arc Welding
• GTAW -Gas Tungsten arc Welding
• SW -Stud Welding
• PAW -Plasma Arc Welding
SHIELDED METAL ARC WELD
SUBMERGED ARC WELDING
Metal inert gas welding,MIG
TUNGSTEN INERT GAS WELDING
BRAZE WELDING
B) ELECTRICAL RESISTANCE WELDING
• Spot Welding
• Seam Welding
• Projection welding
• Flash butt Welding
• Electro slag Welding
• Stud Welding
C) ELECTRICAL INDUCTION WELDING
• Induction Presuure Welding
• Induction Brazing
MECHANICAL ENERGY
• Friction Welding
• Ultrasonic Welding,High freq sound waves
• Explosive Welding
SPECIAL SOURCE WELDING
• Electron Beam Welding
• Laser Welding
ELECTRODE DAMAGE & INFLUANCE
• Absorbtion or loss Moisture
• Cracking & discaling covering
• Contamination
• Oxidation of the cored wire
• Formation of deposits on the surface
Absorbtion or loss Moisture& INFLUANCE
• Porosity in weld metal
• Excessive Projection
• Spattering arc instability
• Visual worsening of seam suface
• Scouring / Blistering in cellulose coating
• Difficulty in removing slag
• Cracking caused by hydrogen
Formation of deposits on the surface
• Absorbtion or loss Moisture
• Cracking & discaling covering
• Contamination
• Oxidation of the cored wire
Welding inspection
• Crack• Bead shift• Burn through• Porosity• Pin holes• Waviness• Under cut• Weld appearance
Weldments - Symbols and Drawing Practices
DWGA130 Overview (Cont.)Primary Reference -
• ISO 2553:1992
Secondary References -
• AWS A2.4:1998
Welding Symbol, Weld Symbol
FIGURE 1: Elements of a Welding Symbol
Elementary Weld Symbols
• Most common are fillet, square groove and flare bevel weld joints
Supplementary Weld Symbols
• Contour symbols not used much in the past
Weld Symbol Orientation
• Reference lines and weld symbol details remain the same regardless of which end the arrow is on.
Weld Both Sides
• Appropriate weld symbols above and below reference lines.
• Dashed line not required where the weld joint is exactly symmetric.
Combined Weld Symbols
• More than one weld type.
• Size specified individually for each.
Fillet Weld Size
• Required minimum weld size dimension (mm)z = leg dimension
a = throat dimension
Butt/Groove Weld Size
• Required minimum throat dimension (mm)
• No direct measurement - requires destructive test and evaluation
Intermittent Weld Dimensions
• ISO vs AWS (App 2)
• Size convention is the same
• Number and length of segments
• Spacing between segments vs AWS ctr to ctr method
Symmetric Intermittent Weld
• Same weld symbol and dimensions both sides
• Dashed line not required
• Anchor welds at each end
Staggered Intermittent Weld
• Usually specified to avoid weld distortion or interference
• Offset dimension specified in detail vs default
• Anchor welds - standard shop practice
Z denotes staggered intermittent weld
Intermittent Weld on Circular Part
• If necessary, start location must clearly be identified
• Weld size
• Number and length of segments
• Spacing between segments (chord dimension)
Weld All Around
• Simplified details
• Exactly the same joint conditions and welds all the way around
Testing methods
DestructiveMechanical,Chemical,
Testing
UltrasonicTesting
D P Testing ,MPT,ECT,
X-RAYAET,LEAK,
NRT,
Visual inspection
WELDING SOUNDNESS
Good welding Practice summary Right Welding
parameter at any time
No Adjustment
MoniteringFor right welding at first
Time and any time
SettingWith error proof
interlock(Poka yoke)
Continuous Improvement ModelWelding parameter entry
RESULTRESULT
EVALUATIONEVALUATION
REPAIR,REPAIR,IDENTIFYIDENTIFYACTION PLAN
Action Name Date
TIME
Trend Chart
GOAL
CheckCheck
PARETOANALYSIS100%
Set alingment
Setting
TIME
CURRENT
WIRE POSITION
DIFT
Wire feed
Input Quality,Good
Fittment,Job
position,
Alingment
VOLTAGE
PM Good Welding
GOOD WELDING CONTRIBUTION
MACHINE
34%
WELDER16%
MATERIAL
14%
OTHERS9%
METHOD27%
CHECK POINTS
Rollequality
Spool quality
Alingnment
Torch setting
Flux baking
FITUP GAP
RUST
Input material Quality
Machine truness
Key Decisions MadeEnsure proper welding
parameter
Set appropriate Time
Correct and monitor the process
Check incoming component
Clean and remove rust,oil
Ensure proper welding.
Meet spec
Weld width
Penetration
Side wall fusion
Quantum Improvement in
terms of
Quality
Cost
Cycle time
•Leading Consultants for 6σ and Cycle time Reduction
•Clients:Citicorp, PwC, ICI, 3M, Telstra
Requirement
Six Sigma’s definition of Defect
NDE
Circumferential Butt Weld Inspection
ll welds shall be inspected. A weld subject to inspection shall be acceptable if inspection shows:
a) No surface cracks
b) No Visible lack of fusion between welds and base metal
c) No craters
d) Uniform Weld profiles
e) That frequency of visible porosity in fillet welds does not exceed one in each 100 mm of length and the maximum diameter does not exceed 2.4 mm That groove welds have no visible porosity.
g) Undercut is not more than 0.5 mm deep.
Repairable