Welders Training Program Manual

8/11/2019 Welders Training Program Manual

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WELDING TRAININGPROGRAM



OUTLINEI.COMPANY ORIENTATION

A. IntroductionB. Safety Standard Practices

II. FUNDAMENTALS OF WELDING

A. Introduction to Welding1. Definition of Welding2. Applications of Welding3. Different Types of Welding Processes4. Basic Tools and Equipments

5. Essentials of WeldingB. Types of ElectrodeC. Joint Design and Welding PositionsD. Basic Welding Physics

E. Types of Welding Processes1. SMAW2. GTAW3. FCAW4. SAW

F. Welding Procedure SpecificationG. Welding Defects

1. Causes and Effects2. Prevention and Repair

H. Introduction to Nondestrutctive TestinI. Introduction to Destructive Testing



FUNDAMENTALS OF WELDING

Welding - the procesresults in joining of through their mtogether by applicatiheat, with or withoapplication of preand with or withoaddition of filler metal



APPLICATIONS OF WELDING

Structural Weld

Piping



TYPES OF WELDING

SMAW Shielded Metal Arc WeldingGMAW Gas Metal Arc WeldingFCAW Flux Cored Arc WeldingGTAW Gas Tungsten Arc WeldingPAW Plasma Arc WeldingSAW Submerged Arc WeldingESW Electro Slag WeldingOAW Oxy-Acetylene WeldingSW Stud Welding



BASIC TOOLS EQUIPMENT

ElectrodesWelding HelmetOther Safety EquipmentHand Tools



ESSENTIALS OF WELDING

Electrod*Based on metal type




Electrode Angle&

Travel Speed




Curre*Based on electrode t



TYPES OF ELECTRODE

Rutile ElectrodeGives a very stable arc and is easy to strike and re-strike

Cellulose ElectrodeHigh penetrating spray type arc

Basic Low Hydrogen ElectrodeContains a high proportion of basic materials such as limestone and fluorides

Iron Powder ElectrodeExhibits high melting rate, deep penetration and minimum spatter loss



E-XXXXElectric Arc

WeldingElectrodes

Position

Tensile Strength Coating Characteristic

Example: E-7018Low Hydrogen, Iron Powder

Flat, Horizontal, Vertical, Ov

70,000psi Tensile Strength

S M W ELECTRODE IDENTIFICATION SYSTEM



EXXT-XElectric Arc Welding Electrodes

Tensile Strength Times 10,000psi

Usability aCa

Indicates an

Position

F W ELECTRODE IDENTIFICATION SYSTEM



WELDING JOINT GEOMETRY

Jo in t

configuration of members

Weld

union between materials caused by heat, and orpressure



Fillet BuCompound




Edge Spot P





Edge Open & Closed Corner L




Tee

Cruciform



TYPES OF JOINT PENETRATION

Included angle

Root GapRoot Face

Angle ofbevel

Root FaceRoot Gap

Included angle

RootRadius

Single -V Butt Single - U Butt



TYPES OF JOINT PENETRATION



SINGLE BUTT WELD PREPARATIONS

Single sided preparations are normally made on thinner materials, or when access from both sides is restri



DOUBLE BUTT WELD PREPARATIONS

Double sided preparations are normally made on thicker materials, or when access from both sides isunrestricted



The root gap is used for electrode accessibility to the root of the joint, the smaller the angle of bevelthe larger the root gap is required to achieve good penetration.

BUTT JOINTS

The root gap must be increased as the bevel angle decreases

BUTT JOINTS



BUTT JOINTS

A double-V butt joint will cut down the amount of welding by one half in comparison to a single-V b

BUTT JOINTS



BUTT JOINTS

A single-V butt joint is used on thinner materials and where access to one side only is possible e.g. pipe li

A single-V butt joint is also more simpler to prepare

BUTT JOINTS



Single-V with backing strip/bar

BUTT JOINTS

- A backing strip or backing bar is used mainly to support the root and to prevent burn throughs fromoccurring

- May be used for large root gaps and reduced bevel angles

- It also allows for a feather edge to be used, no root face required

- A backing strip usually forms part of the weld and a backing bar is usually removable

BUTT JOINTS



BUTT JOINTS

A double-V butt joint cuts down the amount of filler material required

A double-V butt joint reduces the amount of distortion and makes possible alternating the weld passon each side of the joint.

A double-V butt may require the joint to be turned over to complete the other side and access to bothsides is required

BUTT JOINTS



U and J preparations may also be used to reduce distortion and may also be used as doublepreparations

BUTT JOINTS

„U‟ and „J‟ preparations give a more uniform and even distribution of weld metal throughout the dep

the joint and reduce distortion and residual stresses

On thicker sections the „U‟and „J‟ preparations require less weld metal again reducing distortion

saving welding cost

Main disadvantages of these preparations is that they require costly machining and may suffer from

lack of side wall fusion

TRANSITIONJOINTS



TRANSITION JOINTS

Transitioning is carried out to reduce the wall thickness on a joint that has two different plate/pipe

thickness to match the thickness of the thinner plate/pipe.

The transition may be applied by a pneumatic beveling machine or by a disc grinder and it is a norma

requirement to have a minimum length four times the thickness of the misalignment or four times the

thickness of the thinnest plate

The transition may be applied to the inside or outside of the joint, in the case of a pipeline it is

normally applied to the inside

TRANSITIONJOINTS



TRANSITION JOINTS

Abrupt changes in material thickness, causes stress concentrations and low fatigue strength

A smooth transition is required to reduce the chances of fatigue cracking

A taper of less than 1 in 4 is recommended for maximum fatigue strength

TRANSITIONJOINTS



TRANSITION JOINTS

Joints a) and b) are the most common types of transitioning with c) being used to facilitate testing



WELDINGPOSITIONS



WELDING POSITIONS

WELDINGPOSITIONS



WELDING POSITIONS

BASIC WELDING PHYSICS



Electric Current (I)

• Flow of electric charge through an electric conductor• Electric charge flows when there is voltage present across a

conductor• Unit: Ampere (A)





Voltage (V)

• Electrical Potential Difference• Difference in electric potential energy of a unit test charge

transported between two points• Unit: Volts (V)






Power (P)

• Rate at which energy is transferred, used or transformed• Power = Current X Voltage → P = IV • Unit: AV = watt




W

Power (P)

• Rate at which energy is transferred, used or transformed• Power = Current X Voltage → P = IV • Unit: AV = watt




Heat Input (Q)

• Heat supplied by the welding process• Q = k x V x I x 60 where k = thermal efficiency

v x 100 v = travel speed

Process k

SMAW 0.8FCAW 0.8SAW 1.0GTAW 0.6



WELDING PROCESSES

WELDING PROCESSES



Welding is regarded as a joining process in which the work pieces are in atomic contact

Solid state processes

Forge weldingFriction welding

Fusion welding processes

MMA (SMAW)

TIG/TAG (GTAW)

FCAW

Sub-arc (SAW)

FUSION WELDING FACTORS



The four essential factors for fusion welding

1. Fusion is achieved by melting using a high intensity heat source

2. The welding process must be capable of removing any oxide andcontamination from the joint

3. Atmosphere contamination must be avoided

4. The welded joint must possess the mechanical properties required bythe specification being adapted

ARC WELDING SAFETY



Before continuing with the welding processes section, there are 2 safetyrelated terms that should first be understood.

“Duty Cycle” relates to the current carrying capacity of all conductors,based on a 10 minute cycle i.e. 60% duty cycle means it can carry thespecified current for 6 minutes in 10 then must rest for 4 minutes. A 100%duty cycle has no rest period requirement.

ARC WELDING SAFETY



Fume or gas Exposure Limit Effect on Health

Cadmium 0.025Mg/m 3 Extremely tox

General Welding Fume 5Mg/m 3 Low toxicit

Iron 5Mg/m 3 Low toxicit

Aluminium 5Mg/m 3 Low toxicit

Ozone 0.20 PPM Extremely toxic

Phosgene 0.02 PPM Extremely toxic

Argon No OEL ValueO 2 air content to be controlled

Very low toxic

OEL/MEL (Occupational or Maximum Exposure Limit) which is used inreference to fume exposure such as that caused in arc welding. The valuemay be in PPM or mg/m 3 depending on a particulate fume, or a gas. Typ

values in EH/40 are

SHIELDED METAL ARC WELDING



Parent material

Electric Arc

Gas shieldMolten weld pool

Solidified slag

PeBuild up of weld metal

Electrodecovering

Electrode

core wire

• uses a consumable electrode coated in flux tthe weld

• the flux coating disintegrates, giving off spaserve as a shielding gas and providing a layer slag, both of which protect the weld area fromatmospheric contamination




Welding position has a big effect on weld quality.More welder skill is required to weld in the overhead p

(4G), when compared to down hand position (1G)




In the down hand position (1G) the welder can drag the tthe electrode along the joint. In the case of vertical (3overhead welding (4G) the welder always gauges the arc




Current (amps) primarily controls depth of penetration, thigher the current the deeper the penetration. If the current

too high this may lead to high spatter, undercut and thepossibility of burn-through. Arc length is another important consideration in weld quathe arc length is too short the arc will become unstable and

may short circuit. If the arc length is too long, this causes hspatter and incorrect shielding from the atmosphere.

SMAW BASIC EQUIPMENT



Pow

Hold

Inve

sour

Elect

PoweWelding

visor/filter glass

Return lead

Electrodes

Electrodeoven

Control panel

(amps, volts)




Welder controls

Arc length

Angle of electrode

Speed of travel

SMAW VARIABLE PARAMETERS



VoltageThe arc voltage in the SMAW process is measured as close to the arc as possible. It isvariable with a change in arc lengthO.C.V.The open circuit voltage is the voltage required to initiate, or re-ignite the electrical arc awill change with the type of electrode being used e.g 70-90 voltsCurrentThe current used will be determined by the choice of electrode, electrode diameter andmaterial type and thickness. Current has the most effect on penetration.

PolarityPolarity is generally determined by operation and electrode type e.g DC +ve or DC -ve




The four electrode covering types used in SMAW weldin

Rutile - general purpose Basic - low hydrogen Cellulose - deep penetration/fusion Iron Powder

SMAW PREPARATION AND CHECKING



The welding equipment

A visual check should be made on the equipment to ensure that it is in good

working orderThe electrodes

Checking should be made to ensure that the correct specification of electrode is

being used, the electrode has the correct diameter and in good condition. In the

case of basic fluxed electrodes, ensure that the correct heat treatment is being

carried out before use

e.g Baked at 350 ° C, holding 150 ° C, quiver temps 70 ° C

Cellulose and rutile electrodes do not require pre-baking but should be stored i

a dry condition.

SMAW PREPARATION AND CHECKING



OCV open circuit volts

A check should be made to ensure that the equipment can produce the OCV

required by the consumable and that any voltage selector has been moved to thcorrect position

Current & polarity

A check should be made to ensure that the current type and range is as detailed

on the WPS

Other variables

Checks should be made for correct electrode angle, arc gap and travel speed

Safety

SMAW ADVANTAGES AND DISADVANTAGES



Advantages Disadvantages

Field or shop use

Range of consumables

All positions

Portable

Simple equipment

High welder skill requir

Low operating factor*

High levels of fume

Hydrogen control (flux

Stop/start problems

* Comparatively uneconomic when compared to some other processesi.e. SAW and FCAW

GAS TUNGSTEN ARC WELDING



Filler wire

Depositedweld metal

Cap

Switch Han

Shielding gas

Electrode

• uses a non-consumable tungsten electrode toproduce the weld

• the weld area is protected from atmosphericcontamination by an inert shielding gas (argon orhelium), and a filler metal is normally used.

GTAW BASIC EQUIPMENT



Power

Invertersource

Source panel

Power c

Flow-mTungstenelectrodes

Torch assembly

Return lead

Power controlpanel

GTAW TORCH ASSEMBLY



Spare ceramicshielding cup

Gas diffuser

Split collet

On/Off switch

Fitted ceramicshielding cup

Tungstenhousing

GTAW VARIABLE PARAMETERS



VoltageThe voltage of the TIG welding process is variable only by the type of gas being used, andchanges in the arc length

CurrentThe current is adjusted proportionally to the tungsten electrodes diameter being used. Thehigher the current the deeper the penetration and fusion

PolarityThe polarity used for steels is always DC –ve as most of the heat is concentrated at

pole. This is required to keep the tungsten electrode at the cool end of the arc. Whenwelding aluminium and its alloys AC current is used.

GTAW VARIABLE PARAMETERST t l t d



Tungsten electrodesThe electrode diameter, type and vertex angle are all critical factors considered as essenvariables. The vertex angle is as shown

Vertex angleNote: when welding aluminium with

tungsten end is chamfered and forwhen welding

DC -ve

Note: too fine an angle will promote melting of theelectrodes tip

AC

GTAW TUNGSTEN ELECTRODES



GTAW VARIABLE PARAMETERS



Gas type and flow rateGenerally two types of gases are used in TIG welding; argon and helium, though nitromay be considered for welding copper and hydrogen may be added for the welding of

austenitic stainless steels. The gas flow rate is also important .

Argon (Ar) Inert Suitable for welding carbon steel, stainless

steel, aluminium and magnesium

Lower cost, lower flow rates

More suitable for thinner materials andpositional welding

Helium Argon mixes Suitable for welding carbon

stainless steel, copper, alumi

magnesium High cost, high flow rates

More suitable for thicker matmaterials of high thermal co

GTAW PREPARATION AND CHECKING



The welding equipment

A visual check should be made to ensure the welding equipment is in good

condition

The torch head assembly

Check the diameter and specification of the tungsten electrode, the required

vertex angle and that a gas lens is fitted correctly. Check the electrode stick-ou

length and that the ceramic is the correct type and in good condition

Gas type and flow rateCheck the shielding gas if it is the correct type, or gas mixture and the flow ra

correct for the given joint design, welding position as stated in the WPS



GTAW ADVANTAGES AND DISADVANTAGES




High quality

Good control

All positions

Low hydrogen

Minimal cleaning

High skill factor re

Small consumable

High protection req

Low productivity

High ozone levels

FLUX-CORED ARC WELDING



FLUX-CORED ARC WELDING



• requires a continuously-fedconsumable tubular electrodecontaining a flux and aconstant-voltage/constant-current welding power supply

• an externally suppliedshielding gas is sometimesused, but often the flux itself isrelied upon to generate thenecessary protection from theatmosphere.



SUBMERGED ARC WELDING

Filler wire spool



- +

Powersupply

Filler wire spoolFlux hopper

Wire electrode

Flux

Slide rail

• requires a noncontinuousconsumable solid or tubul(flux cored) electrode

• the molten weld and the zone are protected fromatmospheric contaminationbeing “submerged” under

blanket of granular fusibleconsisting of lime, silica,magnesium oxide, calciumfluoride and other compou

SAW BASIC EQUIPMENT



TransRecti

Power return

cablePower control

panel

Weldcontr

Granulated flux

Granulated flux

We

Electreel

SAW FLUXES



Fused SAWFluxes Agglomerated SAW F

SAW FLUXES



Fused Flux

Flaky appearance

Lower weld quality

Low moisture intake

Low dust tendency

Good re-cycling

Very smooth weld profile

Agglomerated Flux

Granulated appearanc

High weld quality

Addition of alloys

Lower consumption

Easy slag removal

Smooth weld profile

SAW ADVANTAGES AND DISADVANTAGES




Low weld-metal cost Easily automated

Low levels of ozone

High productivity

No visible arc light

Minimum cleaning

Restricted welding po

Arc blow on DC curre

Shrinkage defects

Difficult penetration c

Limited joints



WELDING PROCEDURE SPECIFICATIONS



WELDING PROCEDURES

Components of a welding procedure



Parent material• Type (Grouping)• Thickness• Diameter (Pipes)• Surface condition)

Welding process• Type of process (SMAW, FCAW,

TIG, SAW etc)• Equipment parameters• Amps, Volts, Travel speed

Welding Consumables• Type of consumable/diam

consumable• Brand/classification• Heat treatments/ storage

Joint design• Edge preparation• Root gap, root face• Jigging and tacking• Type of baking


WELDING PROCEDURES




Welding Position• Location, shop or site

• W elding position e.g. 1G, 2G, 3G• Any weather precaution

Welding Variables• Run sequences• Back gouging• Interpass temperatures

Thermal heat treatments• Preheat, temps• Post weld heat treatments e.g.

stress relieving




Example:Welding ProcedSpecification (W

WELDERS QUALIFICATION

Numerous codes and standards deal with welder qualification e g BS EN 287



Numerous codes and standards deal with welder qualification, e.g. BS EN 287Once the content of the procedure is approved the next stage is to approve thewelders to the approved procedure. A welders test know as a Weld

Qualif icat ion Test (WQT).

Object of a welder qualification test

To give maximum confidence that the welder meets the requirements of the approvedprocedure (WPS).

The test weld should be carried out on the same material and same conditions as for thesite weldsThe welder who carries out the procedure qualification weld automatically qualify whethe procedure qualifies


Information that should be included on a welders test certificate are:



Information that should be included on a welders test certificate are:

1. Welders name and identification number2. Date of test and expiry date of certificate3. Standard/code e.g. BS EN 2874. Test piece details5. Welding process, welding parameters, amps, volts6. Welding parameters, amps, volts7. Consumables, flux type and filler classification details8. Sketch of run sequence, welding positions9. Joint configuration details10. Material type qualified, pipe diameter etc11. Test results, remarks12. Test location and witnessed by13. Extent (range) of approval


Th i ti f ld lifi ti t t



The inspection of a welders qualification test.

It is normal for a qualified inspectors usually from an independent body to

witness the welding. Under normal circumstances only one test weld per welder is permitted If the welder fails the test weld and the failure is not the fault of the welder e.g

faulty welding equipment then a re-test would be permitted. The testing of the test weld is done in accordance with the applicable code, but

is not normal to carry out tests that measure the mechanical properties of weldse.g. tensile, charpy and hardness tests.



Example:

Welder Approva

QualificationCertification



WELD DEFECTS

Defects which may be detected by visual inspection can be grouped und



y y p g pthe following headings

CracksSolid inclusions

Surface and profiles

Misalignment (set-upirregularities)

Gas pores and porosity

Lack of fusionMechanical damage

Parent material damage

Miscellaneous

Cracks that may occur in welded materials are caused generally by manfactors and may be classified by shape and position Cracks are classed

CRACKS



Classif ied b y Shape

Longitudinal

Transverse

Branched

Classif ied by Posi t ion

HAZ

Centreline

Crater

Fusion zone

Parent metal

factors and may be classified by shape and position. Cracks are classedas planar.



MECHANICAL TESTING

MECHANICAL TESTING



MECHANICAL TESTING



Tensile tests

Toughness testing (Charpy, Izod)

Hardness tests

The following mechanical tests have units and are termedquanti tat ive tests

MECHANICAL TESTING

Th f ll i h i l h i d d



Macro testing

Bend testing

Fillet weld fracture testing

Butt weld nick-break testing

The following mechanical tests have no units and are termedtests

MECHANICAL PROPERTIES

Malleability - Can be deformed a great deal by compression before crack



Malleability Can be deformed a great deal by compression before crack

Ductile -Can be deformed considerably by tension before it fractures

Toughness -Ability to withstand bending without fracture

Hardness -Measure of the resistance of a material to indentation

BEND TEST



To determine the soundness of the weld zone. Bend testing can

also be used to give an assessment of weld zone ductility.

There are three ways to perform a bend test

1. Face bend

2. Root bend3. Side bend

BEND TEST



Weld dressed flush Su

Form

Root bend Face bend

BEND TEST



Defect indicationGenerally thisspecimen would beunacceptable

Minor ruptension

Acceptance du

requ



TENSILE TEST



TENSILE TEST

s t



A l l - W e l d

M e t a l

T e n s i l e T e s



IMPACT TEST



C H A R P Y I M P A C T T E S T

IMPACT TEST



I Z O D I M P A C T T E S T

IMPACT TEST



Object of test

T b k h j i h h h ld i i i

FILLET WELD FRACTURE TEST



1. Specimens are cut to the required length

2. A saw cut approximately 2mm in depth is applied along the fillet welds length

3. Fracture is usually made by striking the specimen with a single hammer blow

4. Visual inspection for defects

To break open the joint through the weld to permit examination othe fracture surfaces

FILLET WELD FRACTURE TEST



MACRO/MICROSCOPIC EXAMINATION



Macro/microscopic examinations are used to give a visual evaluatiof a cross-section of a welded joint

Carried out on full thickness specimens

The width of the specimen should include HAZ, weld and parentplate

Will Reveal




Weld soundness

Distribution of inclusions

Number of weld passes

Metallurgical structure of weld, fusion zone and HAZ

Location and depth of penetration of weld

Measure the leg length and throat thickness

Macro Micro




Visual examination for defects

Cut transversely from the weldGround and polished P400 grit paper

Etched using 10-15% nitric acid solution

Wash and dry

Visual inspection under 5X magnification

Report on results

Visual examination for defects & gra

Cut transversely from the weld

Ground and polished P1200 grit pape

Etched using 1-5% nitric acid solutio

Wash and dry

Visual inspection under 100X-1000X

Report on results

MACRO REPORT



NON DESTRUCTIVE TESTING

A welding inspector should have a working knowledge of NDT methodsand their applications, advantages and disadvantages.

NON DESTRUCTIVE TESTING



Magnetic particle inspection (MT)

Dye penetrant inspection (PT)

Radiographic inspection (RT)

Ultrasonic inspection (UT)

Four basic NDT methods

DYE PENETRANT TESTING



DYE PENETRANT INSPECTION



Simple to useInexpensiveQuick resultsCan be used on any non-porousmaterial

PortabilityLow operator skill required

Surface breaking defect little indication of depthPenetrant may contamincomponentSurface preparation criti

Post cleaning requiredPotentially hazardous ch

MAGNETIC PARTICLE INSPECTION



Surface and slight sub-surface detection

Relies on magnetization of component being tested




Ferro-magnetic materials only can be tested

A magnetic field is introduced into a specimen being testedMethods of applying a magnetic field, yoke, permanent magnet, prods and flexible cab

Fine particles of iron powder are applied to the test area

Any defect which interrupts the magnetic field, will create a leakage field, which attracparticles

Any defect will show up as either a dark indication or in the case of fluorescent particleunder UV-A light a green/yellow indication




Simple to useInexpensive

Rapid results

Little surface preparation required

Possible to inspect through thin

coatings

Surface or slight sub-surfaceonly

Magnetic materials only

No indication of defects dep

Only suitable for linear defe

Detection is required in two

ULTRASONIC INSPECTION TEST



Surface and sub-surface detection

This detection method uses high frequency sound waves typically above 2




This detection method uses high frequency sound waves, typically above 2to pass through a material

A probe is used which contains a piezo electric crystal to transmit and receultrasonic pulses and display the signals on a cathode ray tube or digital di

The actual display relates to the time taken for the ultrasonic pulses to travthe distance to the interface and back

An interface could be the back of a plate material or a defect

For ultrasound to enter a material a couplant must be introduced between tprobe and specimen




The principles of radiography

X or Gamma radiation is imposed upon a test object

RADIOGRAPHIC INSPECTION



Radiation is transmitted to varying degrees dependant upon the density

of the material through which it is travelling

Thinner areas and materials of a less density show as darker areas on

the radiograph

Thicker areas and materials of a greater density show as lighter areas on

a radiograph

Applicable to metals,non-metals and composites




Permanent recordExpensive consumablesBulky equipment





Little surface preparation

Defect identification

No material type limitation

Not so reliant upon operator skill

Thin materials

y q pHarmful radiationDefect require significantrelation to the radiation bSlow resultsVery little indication of d

Access to both sides requ

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