Welding and inspection
Presented to the people in need
Course on
WELDING AND INSPECTION
Presentation on Welding fundamentals,application , Symbol,inspection An Overview by
V UMASHANKAR Info.umashankar@gmail.com Chennai
Introduction
Trainers 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 CAW SMAW GMAW GTAW SW PAW -Flux cored Arc Welding -Carbon arc Welding -Shielded metal arc Welding -Gas metal arc Welding -Gas Tungsten arc Welding -Stud Welding -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
Visual inspection
Destructive Mechanical, Chemical, Testing
Ultrasonic Testing
DP Testing , MPT,ECT, X-RAY AET,LEAK, NRT,
Good welding Practice summary
Right Welding parameter at any time
Setting With error proof interlock (Poka yoke)
WELDING SOUNDNESS
No Adjustment
Monitering For right welding at first Time and any time
Continuous Improvement Model
Welding parameter entry Trend Chart GOAL
Check
TIME
RESULT EVALUATION
REPAIR, IDENTIFY
Set alingment
ACTION PLAN
Action Name Date
100%
PARETO ANALYSIS
PM Good Welding
CURRENT Wire feed VOLTAGE
Setting
Alingment
WIRE POSITION
Input Quality, Good Fittment, Job position,
DIFT
TIME
GOOD WELDING CONTRIBUTION
METHOD 27% OTHERS 9% MATERI AL 14%
MACHIN E 34%
WELDER 16%
Flux baking FITUP GAP Spool quality
Check incoming component Clean and remove rust,oil Ensure proper welding.
Rollequality
CHECK POINTS
RUST Torch setting
Key Decisions Made
Ensure proper welding parameter Set appropriate Time Correct and monitor the process
Alingnment Input material Quality Machine truness
Requirement
Weld width
Leading Consultants for 6 and Cycle time Reduction Clients:Citicorp, PwC, ICI, 3M, Telstra
Meet spec
Penetration
Side wall fusion
Quantum Improvement in terms of Quality Cost Cycle time
Six Sigmas definition of Defect
NDE
Circumferentia l 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
Repairable
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.
