Weld Inspection 1

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Weld Inspection Level 1

Introduction to Welding Definition Introduction to Welding Welding Terminology Physics of Welding

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Definition Welding: A group of processes used to join metallic and nonmetallic materials. Often done using heat but maybe done using pressure or a combination of heat and pressure. A filler material may or may not be used.

Other processes: riveting, forging, cutting, turning, and bending

First used: 2000 BC Modern methods: 1881

Examples of Welding Processes Shielded Metal Arc Gas Tungsten Arc Welding Gas Metal Arc Welding Submerged Arc Welding

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Shielded Metal Arc Welding

Gas Tungsten Arc Welding

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Gas Metal Arc Welding

Submerged Arc Welding

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Introduction to Welding Joint between the materials is melted

Intermixing occurs Upon solidification a metallurgical bond results The weld has the potential to have same strength as the materials being joined Unlike soldering, brazing and adhesive bonds which are not fusion processes

Arc Welding Intense heat to melt metal is produced by electric arc Arc between electrode and metal to be joined

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Shielded Metal Arc Welding

High current, low voltage, AC or DC

The Arc

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Heat in The Arc

Change the arc length Change the shielding gas Addition of potassium salts reduces arc voltage

Metal Arc Transfer Metal is transferred across the arc (consumable electrode) Mechanism of transfer: Molten metal drop touches and transfers by surface tension Magnetic pinch effect Gravity (flat welding) More heat is transferred than non-consumable electrodes

Ionization column must be present to conduct electricity (arc)

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Electrical Supply AC DC, electrode positive DC, electrode negative Selection depends upon: Process Type of electrode Arc atmosphere Metal being welded

Properties of Metals Physical Chemical Mechanical

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Physical Properties Colour Melting Temperature Density (weight per unit volume)

Chemical Properties How the metal reacts in an environment Corrosion Resistance (ability to resist corrosion) Oxidation Resistance (ability to resist combining with oxygen)

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Mechanical Properties Strength (ability to resist load without failing) Tensile strength (ability to resist pulling force) Compressive strength (ability to resist crushing force) Ductility (ability to deform without breaking) Brittleness (inability to resist fracture) Toughness (ability to resist cracking) Hardness (ability to resist indent or scratching) Grain size (important in determining mechanical properties)

Effects of Welding Heat creates stress, affects ductility and toughness Effects of previous heat treating are lost around the weld If done properly usually stronger than the base metal Can effect the chemical resistance

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Expansion and Contraction Metal expands when heated Metal contracts when cooled Expansion and contraction creates stress Welding jigs or fixtures prevent movement but lock in stress

Butt Joint Root Opening

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Butt Joint Root Opening

Butt Joint Distortion

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Tee Joint Distortion

Reducing Distortion & Stress Tack weld Align parts for contraction Use jigs or fixtures Preheat parts Heat treat welded parts

Proper welding procedures

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Heat Treating Pre heating Raise the temperature just prior to welding Entire part is heated Less contraction and stress on cooling

Heat Treating Interpass heating Heating while welding or between passes Minimize expansion and contraction Reduce stress

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Heat Treating Annealing Heat treatment after welding Heated above critical temperature 900° C for mild steel Held at temperature for 1 hour per inch of thickness Slow cooled

Heat Treating Stress Relieving Heat treatment after welding Heated below transition temperature 650° C for mild steel Held at temperature for 1 hour per inch of thickness Air cooled Relieves some of the stress of welding

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Electrical Principles

Voltage Force that causes electrons to flow in a circuit Similar to pressure Measured in volts

Electrical Principles Resistance Opposition to flow of electrons measured in ohms Air gap is resistance If voltage is not sufficient to overcome resistance of gap no arc exists

Higher voltage allows a longer arc Arc stops if voltage is not high enough

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Electrical Principles Current

Flow of electrons measured in amperes Compared to flow of water If there is no arc, no current flows in welding circuit

Units of Measure Micro [µ] = 1/1,000,000 or .000001 Milli [m] = 1/1,000 or .001 Centi [c] = 1/100 or .01 Deci [d] = 1/10 or .1 Kilo [ K] = 1,000 Mega [M] = 1,000,000

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Terminology Welding Technology Fundamentals Page 441 Procedures Handbook of Arc Welding Page 16.1-1

Basic Weld Joints

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Butt Joints

Parts of a Grooved Butt Joint

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Corner Joint

T - Joint

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Edge Joint

Fillet Welds

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Engineering Drawings

Isometric Projection

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Orthographic Projection

Orthographic Projection

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Orthographic Projection

Orthographic Projection

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Orthographic Projection

View Selection

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First and Third Angle Projection

First and Third Angle Projection

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Drawing Lines

Dimensioning

S = size P = position

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Dimensioning Angles

Chamfers

Tapers

Auxiliary Views

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Sectional Views

Sectional Views Mating parts

Typical cross section

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Thread Illustrations

Team Project 2

Prepare a sketch in third angle orthographic projection

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Preparation of Joints for Welding

Preparation of Joints for Welding Flanged Preparation

e = member thickness

Used of relatively thin material Medium efficiency

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Preparation of Joints for Welding Square Butt Preparation with backing

g = root gap Improves probability or full penetration Stress raisers that affect fatigue performance

Preparation of Joints for Welding Single Vee Preparation

ß = bevel angle, α = groove angle, s = root face, g = root gap, = solid angle Optimum joint efficiency require back gouging and welding

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Preparation of Joints for Welding Single Bevel Preparation

α = groove angle, s = root face, g = root gap, Ω = angle of incidence Used for Tee and corner joints Optimum joint efficiency require back gouging and welding

Preparation of Joints for Welding Single U Preparation

α = groove angle, s = root face, g = root gap, β = bevel angle, r = root radius Reduced volume of weld as compared to Vee, less distortion Optimum joint efficiency require back gouging and welding

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Preparation of Joints for Welding Partial U Preparation

α = groove angle, s = root face, g = root gap, d = depth of prepared edge, r = root radius, b = root width

Preparation of Joints for Welding Double Vee Preparation

α = groove angle, s = root face, g = root gap, β = bevel angle, d = depth of of prepared edge Reduced distortion and weld volume compared to single Vee, back gouging preferred before welding second side

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Preparation of Joints for Welding Double Vee Preparation with Broad Root Face

α = groove angle, s = root face, g = root gap, d = depth of prepared edge Used in SAW

Preparation of Joints for Welding Double U Preparation

α = groove angle, s = root face, g = root gap, β = bevel angle, d = depth of of prepared edge

Used for thicker sections Reduced volume of weld as compared to Vee, less distortion

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Preparation of Joints for Welding Double J Preparation

α = groove angle, s = root face, g = root gap, d = depth of prepared edge, r = root radius

Preparation of Joints for Welding

Partial Double J Preparation

α = groove angle, s = root face, g = root gap, r = root radius, d = depth of of prepared edge

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Preparation of Joints for Welding

Mixed Preparation

α = groove angle, r = root radius, l = half width of flat bottom

Welding Symbols

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Welding Symbols F A R T

S (E)

L-P

N

F A R T

S (E)

L-P

N Weld-all around

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F A R T

S (E)

Field Weld L-P

N

F A R T

S (E)

L-P

N Reference Line

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F A R T

S (E)

L-P

N Tail (Tail omitted when references not used)

F A R T

S (E)

L-P

N Specification, process or other reference

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F A R T

S (E)

L-P

N Depth of penetration, size or strength

F A R T

S (E)

L-P

N Groove weld size

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F A R T

S (E)

L-P

N Basic weld symbols

Finish symbol

F A R T

S (E)

L-P

N

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F A R T

S (E)

Finish contour

L-P

N

F A R T

S (E)

Groove angle

L-P

N

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F A R T

S (E)

Root opening

L-P

N

F A R T

S (E)

L-P

N Number of spot, stud or projection welds

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F A R T

S (E)

Length and pitch

L-P

N

Basic Weld Symbols F A R T

S (E)

L-P

N

Designates the specific type of weld

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Basic Groove Weld Symbols Square

Single V Single bevel Double J Double flare

Fillet and Plug Weld Symbols

Fillet Plug

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Single and Double Welds Single

Double

Bevel Groove

J Groove Flare Fillet

Arrow Significance

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Arrow Significance Groove Welds

Arrow Significance Groove Welds

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Arrow Significance Fillet Welds

Arrow Significance Fillet Welds

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Information in the Tail F A R T

S (E)

L-P

N

WeldingSpecification, process process or other reference Welding procedure “Typical” representative of all welds on the drawing

Field Weld

In a place other than original construction Usually in the erection phase

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Melt-thru Symbol

Extent of Welding If length is not specified length is between abrupt changes in direction Length maybe directly dimensioned on drawing Weld all around symbol F A R T

S (E)

L-P

N Weld-all around

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Uses of Weld All Around

Finishing of Weld

C G M R H

Chipping Grinding Machining Rolling Hammering

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Break in Arrow Arrow points to member to be chamfered

Combined Welding Symbols

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Alternate Combined Welding Symbols (AWS A2.4)

Complete Penetration

Note:

CJP = Complete joint penetration or CP = Complete penetration

GTSM = Grind to sound metal

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Groove Welds Key parameters: Depth of penetration Bevel angle Root opening

Three Basic Angles

Θ1 = Bevel angle Θ2 = Groove angle Θ3 = Angle at root

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Dimensioning Double Groove Welds

Depth of Penetration & Groove Weld Size F A R T

S (E)

L-P

N

F A R T

S (E)

L-P

N

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Depth of Penetration & Groove Weld Size

E may be greater or smaller than S

Practice Single Groove Partial Penetration

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Practice Single Groove Partial Penetration

Practice Single Groove Partial Penetration

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Practice Single Groove Partial Penetration

Practice Double Groove Partial Penetration

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Practice Double Groove Partial Penetration

Practice Double Groove Partial Penetration

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Practice Double Groove Partial Penetration

Practice Double Groove Full Penetration

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Practice Double Groove Full Penetration

Practice Double Groove Full Penetration

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Practice Square Groove

Square Groove Requires Full Penetration

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Square Groove

Symmetrical Double Groove Welds

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Optional Joint Preparation

Complete Penetration With Back-gouging

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Complete Penetration With Back-gouging

Complete Penetration With Back-gouging

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Flare Weld

Flare Weld

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Surface Finish

Most common is flush

Welds With Backing Basic Symbol

M = Material of backing bar

R = Removal of backing bar after welding

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Welds With Backing S = Steel

R = Removed

Backing bar size can be placed in tail

Joints With Spacers

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Combination Groove and Fillet

Sequence of Preparation

Solid lines indicate preparation before fit-up

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Sequence of Preparation

Solid lines indicate preparation before fitting

CSA W59

Fillet Welds

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Fillet Welds

Note: vertical side (line) always on left

Equal-legged Fillets

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Fillet Size S = Specified size (size on symbol) Seff = Effective size (size that corresponds to specified size) Sm = Measured size (based on actual measurement)

Fillet Size

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Fillet Size Some countries specify the size of fillet by throat rather than leg

In Canada and USA we use leg ISO (ISO/TC44/SC7) recognizes both, but requires identification: “z” designates leg size “a” designates throat size

Fillet Size

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Unequal-legged Fillet Welds

Size is shown in brackets as: (S1 x S2) Not leg specific

Unequal-legged Fillet Welds

or

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Unequal-legged Fillet Welds Often the which leg size is governed by geometry of joint

Fillet Sizes (With Gaps) Gaps less than 1mm (CSA W59) or 1/16 (AWS D1.1)

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Fillet Sizes (With Gaps) Gaps greater than 1mm (CSA W59) or 1/16 (AWS D1.1) Maximum gap 5mm for material < 75mm thick 8mm for material > 75mm thick Measured size increased by amount of gap

Fillet Welds in Skewed Connections

Beyond this range, weld is considered partial penetration (CSA W59 and AWS D1.1)

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Fillet Welds in Skewed Connections

It is necessary to show a sketch of the weld with dimensions

Length of Fillet Welds

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Length of Fillet Welds

Length of Fillet Welds (Not Specified) Considered to run length of joint to change of direction

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Length of Fillet Welds (Not Specified)

Fillet All-around

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Intermittent Fillet Welds

Intermittent Fillet Welds Common Centre

Symbols Aligned

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Intermittent Fillet Welds Staggered Centres

Staggered Symbols

Fillets Welds With Terminal Ends

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Fillets Welds Surface Finish & Contour

Plug and Slot Welds

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Plug and Slot Welds

Plug and Slot Welds

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Plug Welds Key Parameters: Diameter of hole Angle of countersink Depth of filling Spacing of welds Contour and surface finish

Plug Weld, Diameter

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Plug Weld, Countersink

Plug Weld, Depth of Filling

Complete fill

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Plug Weld, Spacing

Plug Weld, Symbols

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Safety Considerations Pressurized Gases High temperatures and hot surfaces Electrical hazards Fume generation Non-ionizing radiation Ionizing radiation Molten droplets of metal Explosive hazards

Oxy-Fuel Cutting Torch tip selection Oxygen pressure Acetylene pressure Cutting Speed Tip alignment Torch Position

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Tip Alignment

Torch Position

Tilted to 20 degrees away from direction of cutting

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Torch Position

Torch 90 degrees to the surface of the metal

Torch Position

Cutting thin steel

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Cutting Conditions

Good Cut

Cutting Conditions

Preheat flames too small Cutting speed too slow

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Cutting Conditions

Preheat flame too long Top surface melted over Cutting edge irregular Excess slag

Cutting Conditions

Oxygen pressure too low Top edge melted Travel speed too slow

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Cutting Conditions

Oxygen pressure too high Nozzle too small Cut control lost

Cutting Conditions

Cutting speed too slow Irregular, emphasized drag lines

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Cutting Conditions Cutting speed too fast Pronounced break in drag line Cut edge irregular

Cutting Conditions

Torch travel unsteady Cut edge wavy and irregular

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Cutting Conditions Cut lost Not properly restarted Bad gouges at restart point

Shielded Metal Arc Welding

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Shielded Metal Arc Welding Acronyms: AC Alternating Current DC Direct Current CC Constant Current CV Constant Voltage DCEN Direct Current Electrode Negative DCEP Direct Current Electrode Positive OCV Open Circuit Voltage

Current and Polarity

DCEN

DCEP

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Current and Polarity DCEP

Deeper penetration than DCEN

DCEN

Electrode melts faster, less heat to the base metal Used for welding thin materials

AC

Produce a neutral or reducing gas (to protect the weld puddle) Medium depth of penetration

Current and Polarity Manual processes such as SMAW require CC welding machine CC machines sometimes called droopers or droop curve machines A CC machine adjusts to maintain a constant current as small changes in arc length occur

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Constant Current Machine

25% change in voltage 4% change in current

Welding Machines

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Welding Machines Current Type (AC, DC, or AC/DC) Input power requirements (117, 240 0r 550 Volts) Rated current output Duty Cycle Open Circuit Voltage

Rated Current Output

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Duty Cycle How long a welding machine can be used at maximum current Based on a ten minute cycle E.g. 60% duty cycle machine can be used at maximum current for a maximum of 6 minutes out of every 10 minutes. It can be used for longer periods at lower current settings

Duty Cycle

200 amp, 20% duty cycle

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Open Circuit Voltage Voltage of the welding machine when on but not being used. Typically 80 volts compared to closed circuit voltage of 5 to 30 volts A high OCV is required to initiate the arc.

Welding Leads Electrode lead Work lead Electrical resistance increases as diameter decreases and length increases Voltage and current are affected when leads are too small in diameter

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Welding Leads Welding Technology Fundamentals Page 58 Wire Diameter

Suggested Filter Lenses

Sensible 7 thru 14 Shade Adjustability On The Outside Of The Helmet While You Are Welding

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SMAW Electrodes Specified by: AWS A5.1 carbon steel A5.3 aluminum and aluminum alloys A5.4 corrosion resistant steels A5.5 low alloy steels A5.6 copper and copper alloys A5.11 nickel and nickel alloys A5.15 gray and ductile cast iron CSA W 48-01 carbon steel covered electrodes chromium and chromium-nickel covered electrodes low alloy steel covered electrodes

Electrode Coverings 1. Add filler metal 2. Create a protective gas shield 3. Create a flux to remove impurities 4. Create slag to protect bead as it cools 5. Add alloys to improve mechanical and chemical properties

6. Determine the polarity of electrode

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Electrode Size CSA W47-01

Electrode Size AWS Lengths: 9, 12, 14, and 18 inches Diameters: 1/16, 5/64, 3/32, 1/8, 5/32, 3/16, 7/32, 1/4, 5/16, 3/8 inches

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Freezing Characteristics Electrodes manufactured to melt rapidly are called fast-fill electrodes Electrodes manufactured to freeze rapidly are called fast-freeze electrodes Electrodes manufactured to compromise between fast-fill and fast-freeze are called fill-freeze

Electrode Designations AWS Minimum tensile strength in thousand psi Electrode Welding position

E 6010

Utilization

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Minimum Tensile strength Minimum tensile strength of the as deposited metal

Welding Position 1 2 3 4

All position Flat and horizontal fillets only Flat position only Flat, horizontal, overhead and vertical down

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Team Assignment 5 Assignment What electrodes are low hydrogen? What electrodes cannot be used with AC? Which electrodes have iron powder addition? Cellulose is used to improve penetration, what electrodes will provide good root penetration? What electrodes cannot be used for DCEP?

Low Hydrogen Electrodes

*5, 6 & 8

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E 7018 E4918 (CSA W48-01) Low hydrogen Fill-freeze All position 70,000 psi, 490 Mpa Moderately heavy slag easy to remove Smooth quiet arc, very low spatter, medium penetration AC or DCEP Iron powder addition

Electrodes Assignment: Prepare a similar description for E7015, E7016, E7028, E8018, E6010, E6019

Hint: Use references: Welding Technology Fundamentals, Page 74-78, Procedure Handbook of Arc Welding Chapter 6.2, and CSA W48-01 appendix D

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Electrode Storage

Low Alloy Steel Electrodes

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Electrode Designations AWS Minimum tensile strength in thousand psi Electrode Welding position

E 10016-D2 Alloy addition Utilization

Alloy Additions

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Low Alloy Electrodes Assignment: 1. Describe the electrodes E9018-B3L and E6218-B3L 2. Create memory rules to help recall which electrodes are low hydrogen, and which electrodes cannot be used with AC

Chromium and Chromium Nickel Electrodes Electrode

Alloy designation Low carbon Position

E 316L-16 Use-ability 15 all position DC only 16 all position AC/DC, (DC if available) 25 flat or horizontal position only, DC 26 flat or horizontal position AC/DC (DC if available)

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Chromium and Chromium Nickel Electrodes Team Assignment 6: 1. What electrode is used to join 304 stainless steel to 304 stainless steel? 2. What electrode is used to join 316L stainless steel to 316L stainless steel? 3. What electrode is used to join 304L stainless steel to 316L stainless steel? Hint: Procedure handbook of Arc Welding chapter 7.2

Flat Welding Position Striking an arc

Scratch method

Pecking method

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Arc Blow

Stringer Bead

Width of bead 2 to 3 times electrode diameter Height of bead 1/8th bead width

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Weaving Bead

Width less than 6 times

Travel Angle

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Work Angle

Reading The Bead

Good bead

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Reading The Bead

Current too low

Reading The Bead

Current too high

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Reading The Bead

Arc length too short

Reading The Bead

Arc length too long

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Reading The Bead

Travel speed too slow

Reading The Bead

Travel speed too fast

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Gas Tungsten Arc Welding

Current & Heat Distribution

Constant current

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Cleaning Action

Shielding Gases

Argon Easier to start and maintain arc Lower flow rates Less expensive

Helium Hotter arc Deeper penetration Faster welding speeds

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Electrodes

Zirconia: AC only, Aluminum Thoria: Steel and SS Pure: Aluminum

Current Selection

R2 p9.4-2

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Current Selection

Current Selection

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Pulsed GTAW

Arc Starting

High frequency start Electrode contact

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Laying A Bead

Pool formed

Electrode moved to back of puddle, filler added to front of puddle

Rod is withdrawn electrode is moved to front of puddle

Typical SS Welding Procedures

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GTAW Variations Autogenous Automatic Hot Wire Multi-Electrode

Team Assignment 7 Prepare a welding procedure including all the details your team is capable of to perform a full penetration Butt weld to join two 3-1/2” schedule 40, 316L pipe for use in a pressure chemical application.

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Gas Metal Arc Welding

Metal Transfer Short Circuit Globular Transfer Spray Transfer

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Short Circuit

Thin material Out of position Low heat transfer

Globular Transfer

Spatter, flat position

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Spray Transfer

At least 90% Argon

Pulsed Spray Transfer

Above and below transition current Out of position

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Power Supply

Constant Potential Inductance Slope Adjustment No current adjustment

Wire Feeder

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Shielding Gas Type of transfer

Penetration and bead shape Speed of Welding Mechanical Properties of weld

Shielding Gas

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Shielding Gas Argon:

aluminum, nickel, copper magnesium excellent arc stability good penetration and bead profile finger like penetration

CO2

steel reactive gas will not support spray transfer greater spatter and fumes good fusion and penetration

Helium

heavy sections of Al, Cu and Mg higher thermal conductivity additional heat to base metal

Shielding Gas Argon-Oxygen

1 to 8% Oxygen Stainless steel increases droplet rate more fluid puddle reduces undercut

Argon- CO2

Carbon and low alloy steels Most popular 5 to 18% More fluid puddle Higher welding speeds

Argon- Helium

Aluminum, copper, nickel alloys Increased heat input Deeper penetration

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Electrode Wire Rod Solid

Electrode

ER49S-B2 Alloy Tensile Strength [MPa]

Electrode Wire

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Torch Position

Torch Position

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Team Assignment 8

Flux Cored Arc Welding

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Flux Cored Arc Welding Electrodes 1. Gas shielded 2. Self Shielded 3. Metal Cored

Gas Shielded Electrodes Used with same equipment as GMAW Constant voltage Constant wire speed Most are designed for DCEP Gas is usually CO2 or 75% Ar / 25%CO2 Rutile wire:

spray transfer only stable arc, smooth bead good penetration & out of position

Basic wire:

short circuit and globular transfer considerable spatter not easy to use out of position

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Self Shielded Electrodes Very similar to an inside out SMAW electrode Flat and out of position wire Immune to moisture pickup DCEN or DECP, with long stick-out Most fume generation

Metal Cored Electrodes Core contains:

arc stabilizers deoxidizers metal powders

Used with shielding gas Short circuit/globular/spray transfer Out of position with pulsed spray transfer

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Electrode Designations Tensile Strength

Welding Position 1= all, 2 = F groove and F&H fillet

Electrode Tubular or C = metal cored

EXXXT-1 Grouping (27 groups / CSA W48-01)

Refer to CSA W48-01 figure B1

Power Supply

Constant Potential Inductance Slope Adjustment No current adjustment

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Submerged Arc Welding Three to ten times faster than SMAW

Electrodes Typical wire size: 1/16, 5/64, 3/32” Also cored and strip Available for mild steel, low alloy, stainless steel and nickel-base alloys

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Fluxes Manufacturing:

Fused (mixed, melted, fused, crushed, screened & packaged) Bonded (blended dry, binder added, dried, sized & packaged)

Alloy Content of Weld:

Active (Controlled amounts of Mn & or Si to improve resistance to porosity and cracking) Neutral (contains little or no deoxidizers)

Power Supplies DCEN, DCEP, AC DCEP recommended for deep penetration DCEN recommended for: fillets (clean plate) hard facing hard to weld steels greater build-up AC recommended for: tandem arc

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Joint Preparation

Joint Preparation

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Joint Preparation

Backing Required

Electrode & Flux Specification Tensile Strength Heat Treat Condition A = as welded, P = PWHT Flux

Electrode

F XX X X-E L XX X If solid K = killed steel Carbon or chemical analysis Mn L = low, M = medium, Temp of impact strength Z = impact testing not required H = high, C = composite electrode S = single pass only

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Team Assignment 9 Make a short presentation (7 to 10 minutes) to act as a review for your class mates on one of the welding methods.

SMAW GTAW GMAW FCAW SAW

Heating Preheating:

Just prior to welding

Interpass heating

During welding

Post weld heat treatment : After welding

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Preheating Why? Reduce local shrinkage stresses Reduce cooling rate through critical temperature (870º to 720º C) to prevent excess hardening & lowering ductility in weld & HAZ Reduce cooling rate around 205º C to allow more time for hydrogen to to diffuse from weld and adjacent plate material to avoid hydrogen embrittlement and cracking

How Much Preheat? Base metal chemistry Plate thickness Restraint Rigidity of members Heat input of welding process

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Guides for Preheat Specification Note usually given as minimum preheat and is determined by measuring temperature for some distance around the weld Observe minimum ambient temperatures Remember Q&T steels can be damaged if preheat is to high

Guides for Preheat

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W59-03 Appendix P

W59-03 Appendix P

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W59-03 Appendix P

W59-03 Appendix P

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W59-03 Appendix P

Methods of Preheating Production of small parts maybe best in a furnace Natural gas premixed with air Acetylene or propane torches Electric strip heaters parallel to joint

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Measuring Preheat Temperature With the exception of Q&T steels temperatures can be exceeded by 40º C If temperature indicating crayons are used it is best to have one above and one below target temperature Pyrometers, thermocouples and infrared sensors are also Used, calibration and proper use are important

Preheating Quench & Tempered Steel Q & T steel have been heat treated heating above a certain temperature will destroy the properties of that heat treatment The assembly may require preheat but it must not be to high The material must cool rapidly enough to re-establish the original properties Preheating and welding heat input must be closely controlled

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Interpass Temperatures Usually steel which requires preheat is required to remain at that temperature between passes On massive weldments the heat input from welding may not be sufficient to maintain the required temperature Just as it is desirable to control the cooling rate of the weld as a whole it is also important to control cooling between passes Heat from additional sources maybe required to maintain interpass temperatures

Post Weld Heat Treatment Annealing Normalizing Stress Relief

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Full Annealing Purpose: Make steel soft and ductile Reduce stresses

Heat steel to 100º F above critical temperature Hold for 1 hour per inch of thickness Slow cool, usually in furnace

Normalizing Purpose: Reduce stresses, usually after welding Greater hardness & tensile strength than full annealing Heat steel to 100º F above critical temperature Hold for 1 hour per inch of thickness Cool in still air

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Stress Relief Purpose: Provides dimensional stability Softens martensitic areas Improves fracture resistance

Heat slowly to about 625º C Hold for a period of time Slowly cool

Welding Procedures CWB Pre-qualified Joints Not pre-qualified Joints

ASME No pre-qualified joints

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CWB Pre-Qualified Joints CSA W59-03 Section 10 SMAW, FCAW and SAW only Weld Procedure Specification Submit to CWB for Approval Qualify Welders

CWB Not Pre-Qualified Joints Welding Procedure Specification Procedure Qualification CWB Approval Qualify Welders

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ASME Weld Procedures No pre-approved joints Each welding procedure will have a procedure qualification record Three types of variables:

Essential Supplementary Non-essential

What is Included in a Welding Procedure? One welding procedure specification One or more data sheets

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Welding Procedure Specification Scope Welding Procedure Base Metal Base Metal Thickness Preparation of Base Material Filler Material Shielding Gas Position Minimum Preheat and Interpass Temperatures Electrical Characteristics Welding Technique Treatment of Underside of Groove Weld Metal Cleaning Quality of Welds Storage of Electrodes

Data Sheet

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Data Sheet

CWB Welder Qualification Classification Process Mode of Application Position

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Classification S

With backing

T

Without backing

FW = fillet & tack welds, ASW = arc spot weld, WT = tack welds

Process SMAW

SAW

FCAW

ESW

GMAW

EGW

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Mode of Application Manual

Semi-automatic Machine Welding Automatic

Position Class F

Flat position & horizontal fillets

Class H

Flat and horizontal positions

Class V

Flat, horizontal & vertical positions

Class O

Flat, horizontal, vertical & overhead positions

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Electrode Designations F4

Exx15, Exx16, Exx18

F3

Exx00, Exx10, Exx11

F2

Exx12, Exx13, Exx14

F1

Exx22, Exx24, Exx27, Exx28

Team Assignment 10 Review a weld procedure and present your teams understanding to your class

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Verification Functions Develop inspection plans & check lists Ordering and delivery of material Welding procedure specifications Welder qualifications Proper fit up and welding processes Heat Treatment Inspection Inspection Records Nondestructive Testing

Procurement Verification Vendor approval Quantity & Dimensions Material Specification Special Requirements Heat treatment Inspection Nondestructive Testing QA Requirements Documentation Requirements

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Receiving Inspections Quantity Inspections Dimensions Identification Mill test reports or other required documentation Manufacturing defects Weather or transportation damage

Documentation Verification Mill Test Reports Certificates of Compliance Partial Data Reports

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SMAW Electrode Storage Low Hydrogen

Minimum 120º C Used within 4 hours Alternate exposure times maybe approved Portable storage devices maybe approved E49 within 10 hours in portable storage

Non-Low Hydrogen Stored warm and dry Kept free from oil and grease

Preparation for Welding

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Preparation for Welding

Assembly Fillet Welds

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Assembly Groove Welds

Workmanship

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Tack Welds

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Backing

Distortion Control

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Preheat & Interpass Temperatures

Dimensional Tolerances

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Sweep

Camber

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Warpage and Tilt

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Misalignment

Profile of a Fillet Weld

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Fillet Weld Size

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Fillet Weld Size

Butt Weld Profile

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Groove Weld Profile

Butt Weld Profile

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Butt Weld Profile

Undercut

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Butt Weld Profile

Weld Discontinuities

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Incomplete Penetration

Lack of Fusion

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Porosity

Slag Inclusions

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Solidification Crack

Hydrogen Induced Cracking

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Lamellar Tearing

Arc Strikes

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Excess Convexity

Excessive Concavity

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Excessive Reinforcement

Insufficient Reinforcement

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Undercut

Discontinuities Related to Specific Welding Methods SMAW SAW GMAW & FCAW GTAW

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SMAW Spatter

Lower current Check polarity Shorter arc If molten metal running in front of arc, change electrode angle Watch for arc blow Ensure electrodes are not wet

SMAW Undercut

Reduce current Reduce travel speed Reduce electrode size Change electrode angle Avoid excessive weaving

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SMAW Rough Welding

Check polarity Check current Ensure electrodes are not wet

SMAW Porosity

Remove scale rust and moisture Use low hydrogen electrodes Use shorter arc length

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SMAW Lack of Fusion

Increase current Stringer bead technique Ensure joint is clean Check joint fit-up and design

Over Lap

SMAW Incomplete Penetration

Increase current Decrease travel speed Use smaller diameter electrode Increase root gap Proper electrode selection

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SMAW Cracking

Hydrogen induced cracking Low hydrogen electrodes Store electrodes properly Use preheat Smaller diameter electrodes

SMAW Cracking

Hot Cracking Proper fit-up Proper electrode selection Ensure root pass is of sufficient size Check rigidity of joint Check Distortion control techniques

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SMAW Cracking

Solidification Cracking If originating in crater use back step technique If centre bead decrease travel speed

SAW Cracking

Fillet Welds If members 25 mm or greater ensure gap of 1 to 1.5 mm to help with shrinkage Check polarity, usually DCEP but DCEN sometimes used to reduce penetration to help deal with cracking Check wire size, larger wire often used when cracking is a problem Check condition of root pass and fit-up Check bead shape (1-1/4 to 1)

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SAW Cracking

Fillet Welds & T Welds Groove angles should be at least 60º If different materials, weld puddle towards the most weld-able material Increasing stick out reduces cracking tendency Ground at the start end of the weld Decreasing welding speed and current reduces cracking tendency

SAW Cracking

Butt Welds If bead is hat shaped , check voltage and travel speed, may need to be reduced

If the first bead from the second side, after back gouging is cracking check to make sure the width is greater than depth If the steels are of poor weld-ability often reducing current and/or travel speed or increasing stick out reduces dilution and reduces cracking tendency

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GMAW & FCAW Fillet Welds Undercut & overlap are common Check manipulation of the gun to ensure welding of both base metals Slag Check for slag removal between passes Gas Shielding is affected by ambient air movement

GTAW Porosity

Check shielding gas flow rates, leaks etc. Check arc length (too long cannot be protected)

Tungsten Inclusions Check for touching the electrode into the puddle Check for current being to high Check the size and type of electrode

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Team Assignment 11 Identify weld discontinuities in samples provided. Record results

Mechanical Testing

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Bend Tests

Root Bend

Face Bend

Bend Tests

Root Bend

Face Bend

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Bend Tests

Bend Tests

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All Weld Metal Tensile Test

Reduced Section Tensile Test

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Vickers Hardness Test

Vickers Hardness Test

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Hardness Tests Three groups: 

Elastic hardness



Resistance to cutting or abrasion



Resistance to penetration

Resistance to Penetration Brinell Hardness Test A hard steel ball or carbide sphere is forced into the surface under a specified load. Diameter is measured to determine Brinell Hardness BHN = Brinell Hardness Number

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Resistance to Penetration Rockwell Hardness Method Measures the net increase in depth of the impression after a minor load is applied and after the major load is applied 14 different scales C, A & D are the most common scales 15-N, 30-N & 45-N are the most common Superficial scales

Resistance to Penetration Vickers Hardness Test Considered a micro hardness method Uses a square based diamond pyramid The surface dimensions of the indent are measured and converted to hardness Used for measuring case hardening and heat affected zones of welds VHN = Vickers Hardness Number

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Resistance to Penetration Tukon Hardness Method Micro hardness technique Employs a diamond indenter Usually combined with a Vickers unit

Resistance to Penetration Knoop Hardness Method Micro hardness technique KHN = Knoop Hardness Number

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Impact Tests Measures the decrease in fracture resistance caused by sudden loading in the presence of a notch Methods: Charpy Izod Units: foot pounds of joules

Charpy Impact Tests CVN = Charpy V-Notch

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Izod Impact Tests

Transition Temperature Impact test results must include temperature Most materials exhibit a change from notch tough to notch brittle over a very narrow temperature range called the transition temperature Transition temperature is determined by conducting impact tests at different temperatures until an abrupt change in energy required to break the specimen is noted

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