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 UMASHANKARInfo.umashankar@gmail.com

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