Welding and inspection Introduction Inspectors background info 25

Welding and inspection

Introduction • Inspector’s background info … • 25 Years in Welding Inspection by Visual and NDT. • Heavy Equipment Fabrication Construction equipments. • In-Process Inspection of Pressure vessels. • Quality Control 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=

A) ELECTRICAL ARC WELDING • • FCAW SMAW GTAW SW PAW -Flux cored Arc Welding -Carbon arc Welding -Shielded metal arc Welding -Gas Tungsten arc Welding -Stud Welding -Plasma Arc Welding

B) ELECTRICAL RESISTANCE WELDING • • • Spot Welding Seam Welding Projection welding Flash butt Welding Electro slag Welding Stud Welding

C) ELECTRICAL INDUCTION WELDING • Induction Pressure 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 • • • Absorption or loss Moisture Cracking & discaling covering Contamination Oxidation of the cored wire Formation of deposits on the surface

Absorption or loss Moisture & INFLUANCE • • Porosity in weld metal Excessive Projection Spattering arc instability Visual worsening of seam surface Scouring / Blistering in cellulose coating Difficulty in removing slag Cracking caused by hydrogen

Formation of deposits on the surface • • Absorption 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

DWGA 130 Overview (Cont. ) Primary Reference • ISO 2553: 1992 Secondary References • AWS A 2. 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 Monitoring For right welding at first Time and any time No Adjustment

Continuous Improvement Model Welding parameter entry Trend Chart GOAL Check RESULT TIME Set alingment EVALUATION ACTION PLAN Action Name Date REPAIR, IDENTIFY 100% PARETO ANALYSIS

PM Good Welding CURRENT Wire feed VOLTAGE Setting Alingment Input Quality, Good Fittment, Job position, WIRE POSITION DIFT TIME

GOOD WELDING CONTRIBUTION

Flux baking • Check incoming component FITUP GAP Spool quality • Clean and remove rust, oil • Ensure proper welding. Roll equality CHECK POINTS RUST Torch setting Alignment Input material Quality Machine trueness Key Decisions Made • Ensure proper welding parameter • Set appropriate Time • Correct and monitor the process

Requirement Weld width Meet spec Weld appearance Weld cap angle (Abt use angle) Uniform weld bead Uniform reinforcement TO ACHIVE Penetration Side wall fusion • Quantum Improvement in terms of • Quality • Cost • Cycle time • Leading Consultants for 6 and Cycle time Reduction • Clients: Citicorp, Pw. C, ICI, 3 M, Telstra