SMAW. SHIELDED METAL ARC WELDING AWS Classification ARC WELDING STICK WELDING.
Routine Manual Metal Arc Welding
Transcript of Routine Manual Metal Arc Welding
Metals and Engineering Industry5.12AB Perform Routine Manual Metal Arc Welding
ContentsTraining Record 3Introduction 7
Topics 7Prerequisites 7Instructions 7
Competency assessment 7
Section 1 - Introduction to Manual Metal Arc Wdding 9Aim 9
Acti vity 9MMAWelding video response 10
Arc welding 10
Section 2 - Operating Principles for Manual Arc Welding 13Aim 13
Activity 13Electricity 14Hazards 14
Protective clothing 17Maintenance of welding equipment.. 2021Welding machines 23Power source 26
Rating of power sources 29Current range 29Electrodes 30
Basic symbols 33Welding symbols 33\Velding procedures 35Joint preparation 37
Review questions - Operating principles for manual arc welding38Review questions - Weld symbols 42Review questions - Electrode identification - Current settings .. 44
Section 3 - Manual Metal Arc Welding - Basic Welds 45Aim 45
Acti vity 45Manual metal arc welding - basic welds .46
Material preparation 46HOViTto strike an arc 47
Laying down a weld bead 48Weld cleaning 49
Review questions - Material preparation and weld cleaning 50
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Practical exercise 1 - Beads on plate - flat 52Procedure sheet 1 - Beads on plate - flat 54
Practical exercise 2 - Pad welds - flat.. 55Procedure sheet 2 - Pad weld - flat 57
Section 4 - Fillet Weld Joint Terms and Faults 59Aim 59Activity 59
Fillet weld joint terminology and faults 60Fillet weld terminology 60Weld Defects 62Workshop tests 67
Review questions - Fillet weld joint terminology and faults 69Practical exercise 3 - Fillet weld, single run - horizontaL 78
Procedure sheet 3 - Fillet weld, single run - horizontal 80Practical exercise 4 - Fillet weld, 3 run 2 layer - horizontal.. 81
Procedure sheet 4 - Fillet weld, 3 run 2 layer - horizontal. 83Practical exercise 5 - Outside corner fillet - horizontal 84
Prooedure sheet 5 - Outside corner fillet - horizontaL 86Practical exercise 6 - Fillet weld - horizontal 87
Prooedure sheet 6 - Fillet weld - horizontal 89
Seotion 5 - Butt Weld Terminology and Faults 90Aim 90Activity 90
Butt weld terminology and faults 91Weld preparation 91Preparation types 93Weld defects 96
The principle of expansion and contraction in a metal 101Angular distortion 101
Review questions - Butt weld terminology and faults 102Practical exercise 7 - Butt weld, flat sheet steel 108
Procedure sheet 7 - Butt weld, flat sheet steel 110
Metals and Engineering Industry
S.12AB Perform Routine Manual Metal Arc Welding
Introduction
This training guide is designed to support training for the Metal and
Engineering Training Package.
Topics
• Operating principles for manual arc welding
• Manual metal arc welding - basic welds
• Fillet weld joint terms and faults
• Butt weld terminology and faults
Prerequisites
Nil
Instructions
1. Study the information for each topic and complete review
questions
2. Complete the practical exercises.
note
The pr~ctical exercises are suggested only and may be replaced
by any other suitable training activity.
3. The Training Record must be signed by your trainer on
completion of each activity.
4. Complete the theory test. (The test results may be
recorded as part evidence of competency.)
Competency assessment
To achieve competency other approved activities must be entered in theAssessment and Evidence Record section.
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Metals and Engineering Industry
S.12AB Perform Routine Manual Metal Arc Weldiug
Section 1 - Introduction to Manual
Metal Arc WeldingAim
To understand the operating principles, equipment, consumables and
safety requirements for general purpose welding using the manual metal
arc welding process.
Activity
1. View video No. 47 Arc Welding.
2. Complete the video response questions during or
immediately after watching the video.
3. Ask your supervisor or teacher if the information is not
clear to you.
4. Ask your trainer to check and sign your Training Record.
S. On completion of this section you must attempt the test
on this topic and reach the required level of competence
before proceeding to the next section.
Safety
• Wear safety glasses at all times while in welding workshops.
• Follow safe working practices to avoid electric shock.
• Weld in well ventilated areas.
• Wear protective clothing.
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Metals and Engineering Industry5.12AB Perform Routine Manual Metal Arc Welding
Section 2 - Operating Principles forManual Arc WeldingAim
Topractice manual metal arc welding exercises in order for you to develop
the manipulative skills for striking an arc and depositing weld metal on
low carbon steel plate.
Activity
1. Read and study the resource material following.
2. Complete the review questions.
3. Ask for assistance if the information or instructions are
not clear to you.
4. Ask a teacher or your supervisor to check and sign your
Training Record.
Safety
• Follow OHS workshop procedures.
• Protect your eyes from the welding arc and wear the proper
eye protection.
• Wear suitable protective clothing including dry leather gloves.
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The welding process uses electricity and generates heat and fumes. Safety
precautions including wearing protective clothing are important.
Maintenance of equipment and supplies and a thorough understanding of
safety aspects of welding will minimise the risk of accident and injury.
Electricity
Electricity is the flow of electrons through a conductor at a certain pressure
and speed. It's like water running through a hose. Some of the terms
associated with electricity are explained here.
Conductor In welding an electrical conductor is a metal through which
electricity will easily flow. Copper is the most used conductor.
Voltage This is the unit of electrical pressure. The voltage at the terminals
of an AC welding machine is never more than 80 volts for safety reasons.
This electrical pressure (or force) is responsible for the current flow in a
welding circuit.
Amperage This is the measurement of the electron flow,or current, through
an electrical conductor. Amperage is measured in amps. An amp is a unit
quantity of electricity passing through a given point per second. This is
similar to the rate water flows through a pipeline.
Electric arc welding process This is also called manual metal arc welding
or MMAW. In MMAW a high output amperage (low voltage) is passed
through a consumable flux coated electrode and the work piece. This sets
up an electrical resistance between the tip of the electrode and the workwhich causes the electrode to melt off and form a weld bead.
Hazards
Working with electrical equipment can be hazardous. Youmust take proper
precautions and follow the set safety procedures. Hazards in the welding
workshop include electric shock, fumes, heat, glare and harmful rays.
Metals and Engineering Industry5.12AB Perform Routine Manual Metal Arc Welding
Electric shocks - low voltage
Electric shocks are possible on the secondary (low voltage) side of the
welding circuit. They may be caused by:
• working on wet floors - a shock may be felt when putting an
electrode in the holder. Always stand on insulated mats or
wooden boards to reduce the risk and wear dry leather gloves
• working in a very humid climate or rainy weather - a shock
may be felt when changing electrodes. Keep electrodes and
gloves dry.
Electrical shocks • high voltage
High voltage shocks shouldn't happen if precautions are taken such as
ensuring welding machines are maintained by licensed electrical tradesmen
and that you never interfere with the inside parts of the welding machines.
Symptoms of electrical shock
Often electric shock stuns but doesn't kill. However when electricity passes
through the body it causes muscles to contract and can stop the heart
from beating or cause breathing to stop.
Electricity can also cause serious burns.
Fumes
Fumes can result from:
• the production of oxides and nitrous gases from incomplete
combustion or oxidation of nitrogen from the atmosphere
• the surface coatings on steel such as galvanising, cadmium
or chrome plating and paints and solvents such as red oxide
parts/degreasing solvents
• elements within the parent metal
• electrode flux coatings.
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Safety
Welding should be carried out in well ventilated areas. When welding high
fuming materials such asga1vanised steel, use extraction systems to carry
away the fumes. If an extraction system is not available, an approved
respirator should be used to filter out the fumes.
Respirators should only be used as a secondary protection.
Dangerous fumes
Gases, dusts and vapours are given off during welding. They can cause:
• gassing or asphyxiation because the oxygen has been used
up in the work area (common in confined spaces)
• build up of poisonous metals in the body, such as lead,
cadmium, zinc, beryllium or mercury
• respiratory ailments from wheeziness to serious lungdisorders.
Heat
Heat is a form of energy. When a substance is heated the molecules vibrate
or move more rapidly. Heat may be generated by various means. In manual
metal arc welding it is generated by the passage of an electric current
across an arc;:gap.
The electric arc (about 6000°C) generates the heat to melt and fuse themetal surfaces.
Heat is transferred in two ways, by conduction and by radiation.
Conduction Solid bodies must be in physical contact for heat to travel
through them. Some materials conduct heat more rapidly than others.
Metals are generally good conductors but, because of their different
properties, some have a greater conductivity rate than others, for example
copper and aluminium are very good conductors while cast iron and
stainless steel are poorer conductors.
Metals and Engineering Industry5.12AB Perform Routine Manual Metal Arc Welding
Radiation This is the transfer of heat through space by wave motion. No
physical contact is needed. Allbodies at a higher temperature than their
surroundings radiate heat, for example, the sun radiates heat energy in
the form of cosmic rays and an electric radiator transfers heat through
space across a room.
Protective clothing
Protective clothing will help to protect you from heat, hot metal and
harmful rays.
Helmet
Gauntlets
Leather apron
Gaiters,'''-.
Spats ~--..~
Full protective clothing
Protection against hot metal
Molten droplets have a way of getting into boots. You can avoid this by
wearing proper protective clothing and footwear. When welding out of
position wear spats over your boots and under overall legs.
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Metals and Engineering Industry5.12AB Perform Routine Manual Metal Arc Welding
Protection from harmful rays
The harmful rays given off from an electrical welding process are ultra
violet rays and infra-red rays.
These rays can damage the skin. Ray burn is like very severe sunburn;
your skin reddens and then peels. If the ray burn is very severe, there
may be blisters and sores. Rays will also harm the eyes causing a condition
called a flash or arc eye. The first symptom of a flash is an itchy feeling in
the eye. Afterwards a throbbing pain (much like sand in the eye) may
stop you sleeping. There are eye drops that relieve the pain. Continuos
flashes may cause blindness. The use of Safety Glasses will help protect
your eyes from these rays.
Filter lenses These are specially designed glass lenses to filter out harmful
rays and allow you to see what you're welding without causing any changes
in the pupil size or damage to your eyes. Filters come in different shade
numbers, according to the current range or type of welding.
Recommended minimum protective filters
Process
MMAW
ApproximateWelding (AMPS)
Up to 100100 - 200200 - 300300 - 400Over 400
FilterRecommended
810111213
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Safety
• Wear safety glasses at all times.
• Wear appropriate clothing to protect your eyes and skin, from
welding rays.
• Prevention, is the best policy, avoid exposing eyes to harmful
rays.
Metals and Engineering Industry
5.12AB Perform Routine Manual Metal Are Welding
Wear a welding shield or helmet, fitted with the correct filter to protect
you from arc rays, heat and the spatter from molten metal. The filter
reduces the intensity of the radiation, but allows sufficient light through
for you to see the weld pool and the end of the electrode.
Clear glass
Head shield
Swivel filter
hand held shield
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Maintenance of welding equipment
Before carrying out any maintenance on electrical equipment, it's
important that you first switch off the power and remove the plug. If there
isn't a plug, lock off the machine or danger tag the isolator switch.
Transformer
Never do maintenance work inside the case of the welding machine.
Operators can care for the machine by:
• keeping the case clean and dust free
• maintaining the secondary circuit in good condition
• sending the machine to a licensed electrician for any
maintenance on the internal parts, the primary lead and plug.
Machine terminals
Keep terminals clean and tight to ensure that the current will flow freely.
If you don't check nut tightness now and then, you may get arcing and/or
overheating of the terminal and lug connections. This will also be
detrimental to weld quality and machine performance. This can lead tofire or cause burns.
Joints
Loose joints or bad contacts cause cable, clamps and other parts of the
welding plant to overheat and may give you unstable arcing. Use properly
designed cable connectors when you make any joints in cables. Make
sure that good electrical contact is made when you connect cables to the
power source, electrode holder and the return work clamp
Secondary leads (electrode/return lead)
Damaged leads may cause the operator discomfort from overheating, and
poor arcing characteristics. Maintain leads by:
• rolling them up after use
• unroll prior to using
Metals and Engineering Industry
5.12AB Pedorm Routine Manual Metal Arc Welding
• making sure that the ends are fixed correctly into the
electrode holder, work-clamp or terminal lugs
• covering lug connections with insulation tape when necessary.
The size of the cable must suit the output of the welding power source at
the maximum duty cycle (refer to Australian Standard AS1995 on welding
cables for the cable size).
Electrode holders
Electrode holders should suit the minimum output current being used.
The holder should be relatively light, comfortable to hold, fully insulated
and sturdy enough to withstand the wear and tear from constant use. The
holder should be rated to withstand the maximum current required for
the activity.
Retumclamp
This is fastened to the work or to the workbench to complete the welding
circuit. Spring pressure and screw type clamps are normally used. Magnetic
type clamps are also available.
Twist handle to
grip electrode
Insertelectrode
Heavy duty type
Spring-loaded jawsto grip electrode
Electrode holders
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Screw Clamp
Work cable attachments
. -: /0'1~/-..., /- /.a
Cable attachments
Safety
Protect yourself by wearing the following safety clothing:
• overalls or work clothes
• leather apron and/or coat
• welding gloves.
Machine location
Welding machines should always be in a dry protected area as close to the
power outlet as possible.
Protection of others
Welding should be done in special welding bays. When this is not possible,
use portable screens to shield others working in the area from the rays
generated from the arc. You should also put up signs to warn people that
you are welding.
Metals and Engineering Industry5.12AB Perform Routine Manual Metal Arc Welding
Welding machines
Weldingmachines operate with either alternating current or direct current.
Alternating current (AC) welding machines
Alternating current welding machines are transformers which step down
line voltage (240 or 415 volts) to provide a safe welding voltage. The welding
current supplied by the secondary circuit of the transformer is set by the
operator to suit the type and size of electrode and its use.
Transformer welding machines are less complex and slightly less expensive
than other types.
Direct current (DC) welding machines
The direct current output may be supplied by a transformer/rectifier or
generator power source.
Transformer/rectifiers
An efficient and reliable transformer/rectifier is a machine designed to
transform AC input current to DC output current suitable for welding.
Transformer/rectifiers have no moving parts and like the transformer are
quiet to operate, convenient and cost less than motor generated units. If
an AC current is needed from this type of machine, all the operator has to
do is to select the AC output switch.
Transformer/rectifiers are often designed to provide either DC or AC
outputs. DC is normally preferred because of its greater arc stability but
AC may be required at higher currents to avoid arc blow.
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Arc welding power source - AC transforrner
Arc welding power source - mobile engine driven DC generator
Metals and Engineering lndustl)'5.12AB Perlorm Routine Manual Metal Arc Welding
AC transformer setsDC motor generator sets
Portability
These machines generally consist ofMost modern types have features that allowstatic step-down transformers and
portability (especially the self containedthey are considered as stationary
types). They have an undercarriage fitted withtypes.
wheels.
Power supply
The use of these machines isPetrol or diesel engine driven machines canrestricted to the location of the nearest
be used in any location (special applicationsalternating current power point.
may use generators driven by compressed airie mining).
Efficiency
70-90 per cent electrically efficient.40-60 per cent electrically efficient but someMany multi operator sets give higher
modern types compare with alternatingefficiency.
current efficiency.
Polarity
No polarity. A choice of polarity is obtained by a simplereversal of a switch.(DC- or DC+)
Arc blow
Unaffected. Arc blow occurs even in normal currents andthey are difficult to control above 300amperes.
Maintenance
As there are no moving parts to beRevolving and wearing parts add to runningconsidered, maintenance costs are
costs.very low.
Initial costs
Cheaper plant as less construction isMore costly due to generator and motorinvolved.
construction.
Electrodes
Restricted to use of electrodes that areSuitable for all types of electrodes.suitable for alternating current only.
Running
Cheaper running costs due to the useAdded costs due to the use of electric motorscosts
of an installed power supply.or internal combustion engines.
Voltage
Constant open circuit voltage.A variation of open circuit voltage is possiblecontrol
allowing a selection of electrode type andwelding technique.
Arc length
Limited arc length. Greater tolerance in arc length due to thecharacteristics of the machine.
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Metals and Engineering Industry
5.12AB Perform Routine Manual Metal Arc Welding
Power source
A welding source provides enough current (heat energy) to melt the
electrode and the parent metal. Manual metal arc welding machines have
a variable (adjustable) current output that can be set to suit the job and
type of electrode.
Power source terminals and polarity
Electrical connections for a welding machine are illustrated below.
Output terminals on AC machines are marked electrode and work.
On a DC machine the terminals are marked positive (+) and negative (-)
except in the case where the polarity can be changed by means of a polarity
reversing switch. In such cases the terminals are marked electrode and
work with electrode terminal polarity indicated at the polarity switch.
Most electrodes designed for DCoperate on DC electrode terminal positive
(+) while some types of electrodes should be operated on DC electrode
negative (-). Refer to the manufacturer's instructions for polarity selection.
Main voltage415 or 240 volts
WeldM/C
45-80V
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Open circuit 'Voltage (no currentjlowing)
Mctals and Enginccring IndustryS.12AB Perform Routine Manual Mctal Arc Welding
Main voltage415 or 240 volts
Arc voltage (currentjlowing)
Welding cables
A multiple-strand, insulated flexible copper or aluminium lead conducts
the welding current from the power source to the work. A return cable is
needed to complete the welding circuit between the work and the powersource.
Electrode holder
Power source
Cable connections (secondary circuit side)
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Metals and Engineering Industry5.12AB Perform Routine Manual Metal Arc Welding
Open circuit voltage - arc voltage
Power sources may supply direct current (DC) or alternating current (AC)
to the electrode. AC transformers and DC generators supply only one
type of current, but many transformer/rectifiers can be switched between
AC and DC output.
AC power supply is used more often because the cost is lower and the
welding machines are simpler in design. However, DC current has some
advantages. The DC arc is much more stable with certain types of electrode.
DCis better for working with sheet metal because a stable arc is produced.
Engine driven DC models provide welding power where there are no
electrical supply lines available, for example on site work.
The current should remain nearly constant during welding where the
operator's movements tend to vary the arc length. These movements may
be accidental, or deliberate, to control the weld pool. An increase in arc
length win increase the voltage across the arc, however the machine is
designed to control the current close to the amperage set by the operator.
Melting of the electro<i~ is then uniform in spite of the normal variations
when welding.
The open circuit voltage (OGV) is located and measured at the power
source terminals with the machine switched on but no welding current
flowing. This voltage must be high enough to establish an arc, but not so
high that there is risk of dangerous electric shock.
The welder makes the arc by striking the tip of the electrode on the work
to cause a momentary short circuit. This is at the point on the graph
where V = O. With current flowing, the electrode is drawn away by the
welder to establish the arc. The amperage and voltage for a typical arc
length are shown at point x. For a longer arc length, there is significant
increase in arc voltage and a sman decrease in welding current (point y).
The welding machine is designed to avoid noticeable changes in current
output when the welder varies the arc length.
Metals and Engineering Industry5.12AB Perform Routine Manual Metal Arc Welding
60
60:l!! 40
0:>
200
SO
100150200250
Amps
Output curvefor constant current power source, adjustedfor minimum current'Variation
Rating of power sources
Australian Standard AS1966 rates the output (duty cycle) of electric arc
welding power sources. The machines are classified according to the type
of service for which they are designed, for example: continuous duty, heavy
duty, light industrial or limited output cycles.
The standard defines each of the classes according to the output (load
current, load voltage) needed for a nominated duty cycle. The duty cycle
allows for the Jact that in any five minute period, current for welding may
be drawn for only part of that time. For example, if welding is for a
maximum of three minutes in any five minute period, the machine only
operates up to 60% duty cycle (3/5 of 5 minutes). A much lower current
must be selected for continuous (100%) operation.
All power sources must display a name plate stating the equipment class
and the rated output and duty cycle for its class (eg 300 amps, 32 volts,
60%duty cycle). The 100%duty cycle output current must also be noted.
Current range
The manufacturer's recommendations on the range of current for different
types and sizes of electrodes will only give you their lower and upper
current range.
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Packet of electrodes
130-170
185-235140-200
105-150100-130
130-170
95-150
140-200
90-140
130-190
You should use the recommended amperage and electrode type and size
as stated in the procedure sheets for the practical exercises. This will
help you gain the experience to select the electrode type and size for
future welding exercises.
Electrodes
Electrodes are available in different types.
4113~~
The choice of current will depend on such factors as weld position,
thickness of the joint parts, root gap and access to the structure.
Metals and Engineering Industry
5.12AB Perform Routine Manual Metal Aro Welding
EXX12 Electrodes These have rutile coatings with other constituents
added to form a gaseous shield and slag modification. These electrodes
are easy to use in any positions (including vertical do\'\rn).They operate
with a quiet, medium penetrating arc able to bridge gaps or misalignedsections. These electrodes are general purpose electrodes used forstructural and sheet steel fabrication.
EXX13 Electrodes These also have a rutile coating, similar to the EXX12
type, but they produce a more fluid and easily removed slag (not suitable
for vertical down) with a very neat and flat profile. They are generally
Typical current ranges for the electrode classifications
130-160
75-1253.25
4.0
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5. 12AB Pertonn Routine Manual Metal Arc Welding
more suited to overhead and vertical welding in an upwards direction
than EXX12. They have good X-ray and impact qualities. (these qualities
vary dependant on the impact grading number)
The effect of moisture on electrodes
Any electrode that absorbs excessive moisture into the coating may cause
one or more of the following problems:
• porosity
• excessive spatter
• arc instability
• poor weld contour
• undercut
• difficulty in slag removal
• cracking through hydrogen embrittlement.
Storage
All types of electrode should be stored in their original packaging in a
weather proof area on racks clear of the floor. They should be stored away
from moistvre and high humidity and possible damage.
Storage in an unheated room is satisfactory for a period of less than six
months. If storing for more than six months, or if in tropical or very wet
climates, all electrodes except cellulose types (EXXIO,EXXll) should be
stored in a room or insulated building heated to 15°C to 20°C room (or
ambient) temperature, but at no time more than 40°C. Electrodes stored
in hermetically sealed (airtight) boxes need not be kept in such anenvironment.
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Never tear electrode information data from the boxes. This can lead to
confusion and/or improper use of electrodes.
Storing electrodes
Welders are responsible for the care and handling of electrodes on the
shop floor or work site.
Electrodes should be kept clean and dry.
Defective electrodes should not be used. Discard electrodes or which are
wet or seek manufacturer's advice. Don't use electrodes showing signs of
rust or of damaged coating.
Only remove from the packet the number of electrodes you need for the
next few hours or the immediate job in hand. This reduces the risk ofcontamination and waste.
Metals and Engineering Industry
5.12AB Perform Routine Manual Metal Arc Welding
Unseal packets of electrodes just before you use them and not before.
Basic symbols
Basic symbols which are used to denote the type of weld are illustrated in
Backing strip Weld allField orSurface shapeor bar
roundsite weldFlushConvex
0 ~ C\.
the table below. Also shown are a number of instructional symbols used
to impose certain requirements on the actual welding operation.
Welding symbols
Arrow connectingreference line
to joint
SrS
/::!Fi'eld or site of weld4eld all round
r--t~'-lI L1J WUJ rI 0 :I:o II _ ~_ t
I U'} Ot/) I
I :r: ~ I
I b Ow If m 0:::0 II 0:::_IL__ ~lflJ
F(N)
Number of stud, plug,slot,spot or projection welds
Basic weld symbol area
Spacing between intermittent welds
Tail of reference line (omittedwhen reference P is not used)
The standard welding symbol used to represent welds on drawings is shown
below. The symbol can be used in many ways.
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Metals and Engineering Industry
5.12AB Perform Routine Manual Metal Arc Welding
note
Information relating to a particular weld, such as S, (N), F, W,
(M) must be placed on the same side of the reference line as
the symbol for that weld.
Symbol belowreferenceline
Symbol abovereferenceline
Application of the standard welding symbol
When applying the standard welding symbol, thought must be given as to
whether the actual weld is situated on the same side of the joint as thearrow or on the other side.
Arrow 1
W is called the arrow side of joint 1
X is called the other side of joint 1
Arrow 2
Z is called the arrow side of joint 2
Y is called the other side of joint 2
Arrow 1 bears no relation to arrow 2 as they refer to different
joints.
For weld A, the basic fillet symbol is placed underneath the reference line
indicating that the weld is on the arrow side of joint 1.
For weld B, however, the basic fillet symbol is placed above the reference
line indicating that the weld is on the other side of joint 2.
Metals and Engineering Industry5.12AB Perform Routine Manual Metal Arc Welding
Wherever possible, the arrow should be positioned adjacent to the weld,
as with joint 1, with the symbol underneath the reference line.
Welding procedures
It is sometimes necessary to specify certain procedures or requirements
about a weld. The standard symbol used in such cases should be provided
with a tail as shown on the previous page and the information inserted
where shown, for example, at P.
In order to control a welding process more fully, a procedure sheet may
be added to the drawing. The sheet should contain the following generalinformation.
• type of material being welded;
• form of weld (to include plate preparation such as angle of
bevel, root penetration, root radius, etc.);
• set-up details such as welding position, alignment, gap
required;
• number and order of runs;
• electrode size, type and make (consultAS1552, Classification
of Covered Electrodes);
• electrical supply data such as polarity, current and voltagevalues;
• preheating requirements;
• pre- and post-weld cleaning procedures;
• treatment of joint after welding;
• preparation and/or procedures to apply in between runs.
The arrow is cranked as shown below and points towards the plate
which has to be prepared. The crank is omitted when the edge to
be prepared is abvious, for example, a tee but joint.
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Metals and Engineering Industry
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Symbol below the horizontal reference line.This indicates that the weld is to be placedon the same side as the arrow.
Symbol above the horizontal reference line.This indicates that the weld is to be placedon the opposite side to the arrow.
Symbol below and above the horizontalreference line. This indicates that the weld is to
be placed on both sides of the arrow.
Weld ISymbolICross SectionIDrawing ApplicationIDrawing Explanation
a) Seal bead weld at the
Jkt1 LEarrow side
Bead
ICsI
~b) Bead weld at the arrow side
c) Single bevel butt on
the arrow side with aNo edge preparation
abc bead weld on the other side
,bk;~~
a) Filet weld at the arrow side
Fillet
I1"- II'...'f~ b) Filet weld on the other side
of the jointc) Filet weld on both sides of
a
bcthe joint
a) Single V butt weld on
I~~ 11the arrow side
Single IVI~\}m b) Single V butt weld onVthe other side
c) Single V butt weld onthe other side groundEdge preparation required I a bcflush
~;v;
IOrll~""\.::'::::? ~
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Metals and Engineering Industry5.12AB Perform Routine Manual Metal Arc Welding
Joint preparation
The arrow may also be used to indicate when one plate only of a joint is to
be prepared in welding single bevel and single J butt joints.
The arrow is cranked as shown below and points towards the plate which
has to be prepared. The crank is omitted when the edge to be prepared is
obvious, for example, a tee but joint.
Actual weld
Plate to bebevelled
End view
Crankedarrow
Front view
~~:~~ooeclfue~o~m~~~~u~d
37
Metals and Engineering Industry
5.12AB Perform Routine Manual Metal Arc WeWing
Section 3 • Manual Metal Arc Welding •Basic Welds
Aim
Topractice manual metal arc welding exercises in order for you to develop
the manipulative skills for striking an arc and depositing weld metal on
low carbon steel plate.
Activity
1. Read and study the resource material following.
2. Complete the practical exercises.
3. Ask for assistance if the information or instructions are
not clear to you.
4. Ask a teacher or your supervisor to check and sign your
Training Record.
5. These are skill practice exercises which are assessed. You
must reach the required standards to enable progressionto the section .
Safety
• Follow OHS workshop procedures.
• Protect your eyes from the welding arc and wear the propereye protection.
• Wear suitable protective clothing including dry leather gloves.
45
Metals and Engineering IndustryS.12AB Perform Routine Manual Metal Arc Welding
Manual metal arc welding - basic welds
The following instructions will provide you with basic information about
material preparation, striking an arc and laying down a weld bead. The
cleaning requirements for a finished weld will also be identified along with
the equipment used for this task. Read them carefully before attempting
the four practical exercises in this section.
Material preparation
Cleaning
A welded joint on low carbon steel (mild steel) requires the material to be
cleaned in such a way as to remove all matter that may contaminate the
weld runs (beadlbeads). This can be in the form of Mechanical or Chemical
cleaning. If chemical cleaning is to be carried out it is critical that all
safety factors are adhered to as chemicals may produce dangerous
substances when heated by the arc. Consult the Material Safety Data
Sheet (MSDS) or the manufacturer/distributor if you are not sure about
using any cleaning agents.
Mechanical cleaning
The weld area may be machined. This preparation will generally require
minimal cleaning. If the material is flame cut or hot rolled it will have an
oxide skin that will need to be removed. This will usually require grinding
as wire brushing may not be aggressive enough to bring the material backto bare metal.
Aggregate blasting such as sand or other particles may be also used toclean the weld area.
Tools used for cleaning
The hand held power tools that are used for material removal may include:
46
Angle grinder
Straight portable grinder
Die grinder
Belt sander
Grinding or sanding
Grinding or wire brushing
Aleta!s and Engineering Industry
5.12AB Perform Routine Manual Meta! Arc Welding
These tools can be either pneumatic (air driven) or electric. A floor
mounted pedestal grinder may also be used for material removal.
The practical exercise in this module will require you to use an electric
angle grinder.
How to strike an arc
Preparation
1. Select a piece of steel and after material preparation placeit on the work bench.
2. Select a 4.0 mm E4112 or E4113 Manual Metal Arc
electrode.
3. Set amperage on power source to approximately 165
amps.
4. It is important that you get yourself into a comfortable
and relaxed position when welding to counter the effects
of body sway, movement restrictions and heat generated
by the arc. To get comfortable you can be seated, lean
against the bcnch or lean against a wall in the welding
bay.
Striking the arc
1. Turn on the power source.
2. Lightly touch the end of the electrode on to the work and
you will complete the circuit and current will flow.
3. The electrode end rapidly heats, melting sufficiently to
momentarily weld the electrode on to the work.
4. Due to the low voltage current we are using the arc will
not jump an air gap (as in a spark plug). Wemust therefore
establish an arc by first touching the end electrode onto
the work and then immediately, lengthen the distance
between end of the electrode and work allowing droplets
of metal and flux to cross the ARCGAP(3 mm approx.) to
form a molten pool.
47
48
Metals and Engineering IndustryS.12AB Perform Routine Manual Metal Arc Welding
5. If you fail to do this, droplets will bridge the arc gap,
causing a short circuit and a freezing of the electrode endonto the work.
6. If your action is incorrect and the electrode freezes onto
the work, that is becomes welded or stuck to it, a sharp
backward angling of the electrode should break it free.
7. Keep your head shield over your face, as an arc flash willoccur as the electrode breaks contact.
Laying down a weld bead
1. Once the arc has been established, reduce the arc length
to about 3 mm and note that molten metal is beginning
to mount up under the end of the electrode.
2. Start moving the tip of the rod slowly away to the right,
(if you are left- handed, to the left) endeavouring to
maintain a molten pool approximately 8mm wide behindthe arc.
3. You will have to feed in the electrode as it burns off,
maintaining a steady rate across the plate using the correct
arc length.
4. Continue to deposit a beadlbeads across the plate.
5. Remove the slag cover and wire brush and inspect yourweld.
6. A little more practice and some of these actions will begin
to happen automatically.
7. Remember, not all people are born natural welders.
8. Welding requires practice to gain the necessary skills to
lay down consistent welds. You only obtain these skills
by running lots of electrodes and concentrating on what
you are doing.
Metals and Engineering Industry
S.12AB Perform Routine Mauual Metal Arc Welding
Weld cleaning
It is important that the finished weld is of an acceptable standard free of
slag and adhering spatter. The finished appearance may be given in job
specifications and may require additional work. This may need to be
ca.rried out before the final finish is added to the completed job/component.
Cleaning may just require you to use a chipping hammer and a wire brush.
It could also require you to use the following tools.
Angle grinder
Straight portable grinder
Die grinder
Belt sander
Chisel (hand, electric, air)
File
Grinding or sanding
Grinding or wire brushing
Peening gun (electric, air) used to remove slag.
By the removal of slag and spatter many welds on fabrication work are left
as cleaned. Additional treatment such as machining, sand blasting, grinding
and sanding are after treatments that may be carried out by other personnel
in the manufacturing process. The practical exercises in this module will
require you to use a chipping hammer, chisel and wire brush.
49
Metals and Engineering IndustryS.12AB Perform Routine Manual Metal Arc Welding
Practical exercise 1 - Beads on plate flatAim
To develop the skills to deposit uniform weld beads to the standards below.
Material
1 piece low carbon steel 75 x 10 x 225 mm
Consumables
Mild steel electrodes 4.0 mm E4112 or E4113 at approx. 165 amps.
Instructions
Check the following points:
Amperage setting and heat input, position of the plate on the
bench, correct method of arc striking, correct arc length, correct
welding speed arid travel, electrode angles. Your teacher will
demonstrate if required.
1. Obtain your MMA welding board, safety equipment (head
shield, gloves), material, and consumables (if necessary)from the store.
2. Position the plate on the bench so that a right handed
operator would weld across the body from left to right
(left hand opposite direction).
3. Deposit a weld bead along the plate length, maintaining
the angles as shown, and an arc gap of approximately 2-3mm.
4. Deposit additional runs parallel to the plate edge
approximately 10mm apart.
5. When the top surface of the plate has been covered, turn
the material over and repeat the exercise.
Metals and Engineering Industry5.12AB Perform Routine Manual Metal Arc Welding
6. Evaluate the weld exercise and complete the proceduresheet.
7. Submit your completed weld and procedure sheet forassessment.
Economy
Materials and consumables are expensive. Use electrodes to 50 mm
maximum stub length.
Standards
Your work should have:
• uniform beads with consistent, even restarts, free from slagand spatter
+2
• bead height 3 -1 mm.
53
Metals and Engineering Industry
5.12AB Perform Routine Manual Metal Arc Welding
Procedure sheet 1 - Beads on plate - flat
Electrode
View A
11- Start,.
~B
A~
VlewB
Weld current dataRun 1
23
Electrode dataSize
Type Rutile
Brand Name
Electrode AnglesLead
60°' 80°Lateral
90°
Material data
TypeThickness
Low carbon steel
10mm
Assessment Complies
Workshop safety
54
Metals and Engineering Industry5.12AB Perform Routine Manual Metal Arc Welding
Practical exercise 2 - Pad welds - flat
Aim
To deposit a pad weld on low carbon steel plate in the flat position.
Safety
• Follow OHS workshop procedures.
• Use an approved shade 10 welding glass filter.
• Wear suitable protective clothing to stop ray burn.
• Always wear your safety glasses when removing slag.
Material
1 piece low carbon steel 75 x 10 x 225 mm
Consumables
Mild steel electrodes 4.0 mm E4112 or E4113 at approx. 165 amps
Instructions
Check the following points.
Setting of amperage and heat input, position of the plate on the
bench,' correct method of arc striking and arc length, correct
welding speed and travel, electrode angles. Your teacher will
demonstrate if necessary.
1. Obtain your MMAwelding board, safety equipment (head
shield, gloves), material, and consumables (if necessary)from the store.
2. Outline, with chalk, a rectangular shape 40 x 200 mm.
3. Position the plate on the bench.
4. Deposit a weld bead along the plate length, maintaining
the angles shown.
55
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Metals and Engineering Industry
5.12AB Perform Routine Manual Metal Arc Welding
5. Remove all slag from each individual weld bead before
depositing subsequent runs. Each run must have a
staggered stop and restart.
6. Build up the pad to the required dimensions and on
completion, evaluate your weld with the given standards.
7. Fill in all the relevant information on the procedure sheet.
8. If it meets the standard, submit your work for assessment.
Economy
Use electrodes down to a stub length of SOmm maximum.
Standards
Your work should have:
+2
• pad weld height 3 -1 rnm
• a maximum of four significant surface defects on a unit area
of 40 x 150 mm with the accumulative area not exceedingthe square of the plate thiclmess
• no adhering slag or spatter.
Metals and Engineering Industry5.12AB Perform Routine Manual Metal Arc Welding
Procedure sheet i-Pad weld - flat
First run Subsequent runs
Weld current data
Run 123
~B
View A
View B
Electrode data
Size
TypeBrand Name
Electrode AnglesLead Lateral.. .
Material data
TypeThickness
Assessment
Low carbon steel
10mm
Complies
Workshop safety
57
Metals and Engineering Industry5.12AB Perform Routine Manua! Meta! Arc Welding
Section 4 - Fillet Weld Joint Terms andFaults
Aim
To learn the basic terminology (technical language) used to describe weld
positions, areas and locations of a welded joint, and common defects andtheir causes.
Activity
1. Read and study the resource material following.
2. Complete the review questions.
3. Ask for assistance if the information is not clear to you.
4. Complete the practical exercises at the end of the section.
5. Ask a teacher or your supervisor to check and sign your
Training Record.
6. On completion of this section you must attempt the test
on this topic and reach the required level of competence
before proceeding to the next section.
Safety
Wear the right clothing to protect you against rays and hot metal
spatter.
59
Metals and Engineering Industry5.12AB Perform Routine Manual Metal Are Welding
Fillet weld joint terminology and faultsIt is important for you to know the terms used to describe fillet weld
joints and fillet weld defects so that you are able to talk to other trades
persons, clients and inspection authorities in an informed way. An
understanding of the technical terminology will also assist you to get the
most out of your training.
Fillet weld terminology
60
Positions of welds
Overhead
Lap weld-
Fillet weld
Weld names
[vertic.al
·.]1~1
\I.•..~-
r "--... .•
/ Vertical/
Horizontal
Single v.,~ butt weld
Intermittentfillet welds
'....- Plug weld/'-.--- Slot weld,/
-'--- Corner weld
Metals and Engineering Industry
S.12AB Perform Routine Manual Metal Arc Welding
Definition of a fillet weld
A fillet weld is a weld of approximately triangular cross-section which is
formed in the corner between surfaces of two components.
0--
Parts of a fillet weld Fillet weld contours and
measurements1.
Parent metal 7.Heat affected zone
2.
Reinforcement 8.Root
3.
Fusion zone 9.Penetration
4.
Weld face 10.Leg length
S.
Weld metal 11.Nominal throat thickness
6.
Toe 12.Throat thickness (convex fillet)
13.
Throat thickness (concave fillet)
Parts of a welded structure
Parent metal
Fillet weld
/penetration/fUSion. Weld face
61
Metals and Engineering Industry5.12AB Perform Routine Manual Metal Arc Welding
Fillet weld dimensions
The size of a fillet weld is determined by the following dimensions. These
can easily be checked with a fillet gauge. Note that the strength of a welded
structure is determined by the type of metal, leg length and the effectivethroat thickness.
62
Fillet weld dimensions.
Fillet weld profiles
Weld Defects
Weld defects are either external or internal.
External defects can be detected by visually inspecting the finished weld
for plate misalignment, incomplete penetration, weld craters, blowholes,weld spatter and correct weld size.
Internal defects can only be detected by destructive or non destructive
testing, which may reveal slag inclusions, porosity, cracks and incomplete
fusion or incomplete penetration.
Metals and Engineering Industry5.12AB Perform Routine Manual Metal Arc Welding
Common weld defects
The most common weld defects are:
Undercut
A sharp groove at the toe of a ron between the weld and the parent metal
or in previously deposited weld metal, due to welding. It may be continuousor intermittent.
This is caused by using the wrong electrode angle, excessive welding
current, incorrect operating technique or excessive arc length.
~Undercut~
Over roll (overlap)
Weld metal at the toe of a weld which covers the parent metal surface but
is not fused to it. It is caused by overflowing molten weld metal on the
surface of unmelted parent metal which leaves an unwelded area. This is
caused by using too Iowa current or too slow welding speed, or by using
too large an e!ectrode.
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Metals and Engineering Industry5.12AB Perform Routine Manual Metal Arc Welding
Misalignment
Misalignment is any variation from line or dimension of a welded joint. It
is caused by faulty setting up of job, distortion or lack of tack welds.
Misalignment
Incomplete penetration
Incomplete penetration may be classified as an internal or external weld
fault. Incomplete penetration is the failure of the weld metal to fill and
fuse the root of the joint. It is caused by faulty preparation of work, using
too Iowa welding current or poor operating technique.
Incomplete penetration
Slag inclusions
Slag inclusions are non-metallic particles trapped in the weld metal. They
may weaken the weld joint. Inclusions result from not removing slag from
previous runs, using too Iowa current or using too long an arc length.
64
Inclusions
Metals and EngIneering Industry'
5.12AB Perform Routine Manual Metal Arc Welding
Porosity
Gaseous substances such as oxygen or nitrogen trapped in the weld metal
leave a cluster of small holes in the weld. It is caused using wet or damp
electrodes, welding over coated surfaces, over painted oily or greasy
surfaces or by using the wrong type of electrode.
Cracking
A variety of different types of cracks may occur in the welded area of
fabricated products. Identifying the type of crack helps to isolate the
possible causes. Causes are using wrong type of electrode, not applying
preheat to crack sensitive steel, using damp or wet electrodes or weldingover oil, grease or a plated metal surface .
..•.../I..
Lack of fusion
Incomplete fusion between weld metal and weld metal or weld metal and
parent metal is caused by not enough amperage, incorrect joint preparation
and incorrect welding technique.
Lack of fusion
65
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Metals and Engineering IndustryS.12AB Perform Routine Manual Metal Arc Welding
Undersized and oversize welds
Welded joints are designed by structural engineers to carry loads safely.
The size and type of weld depends on its use. An undersized weld might
not be strong enough to carry the load it supports. A weld that is reinforced
(over welded) too much can make other sections of the work too rigid andcause them to crack or break.
You will be asked to weld to the designer's specification. For example
• a 6 mm fillet weld requires a 6mm leg length and a 4.2 mmthroat thickness
• a butt weld requires an even or slightly curved surface.
You may not be given the weld size for all jobs. If no weld size is specified,
deposit the weld in proportion to the plate thickness. For example:
a 10 mm plate requires a 10 mm weld thiclmess.
Butt welds should always be built up to the thickness of the parent metal.
Oversize
Correctsize
"\\Undersize
Weld assembly (undersized welds)
Metals and Engineering Industry
5.12AB Perform Routine Manual Metal Arc Welding
Workshop tests
These are only some of the tests which call be carried out to check the
weld quality.
Visual
Youcan do a visual check for external weld defects. Internal ones can't be
seen.
Fillet break
A fillet break shows satisfactory fusion, penetration, and inclusions or
porosity.
Summaryof weld defects and how to fix them
When preparing the plate, check that you have:
• correct edge preparation
• clean/smooth surfaces
• correct plate alignment.
When welding, check that you have:
• correct electrode
• correct current (amperage)
• correct speed of travel
67
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Metals and Engineering Industry
S.12AB Perform Routine Manual Metal Arc Welding
• correct arc length
• correct operation (welder).
When checking the electrode for condition, check for damp or damagedelectrodes.
When inter-run cleaning remove all slag, rust, undercut, and excess weld
spatter before depositing the next pass.
78
Metals and Engineering Industry
5. 12AB Perform Routine Manual Metal Arc Welding
Practical exercise 3 - Fillet weld, singlerun - horizontal
Aim
To deposit 6 mm fillet weld in the horizontal position on 10 mm low
carbon steel plate.
Note
This is a skill practice exercise which is assessed. You must
reach the required standards to enable progression to the nextsection.
Safety
• Youmust wear eye protection .
• Make sure that the centre of the press ram and the highest
point of the exercise are in line when breaking welds.
Material
2 pieces low carbon steel 75 x 10 x 225.
Consumables
4 mm 4112 or 4113 electrodes at 160 to17S amps approximately.
Instructions
Your teacher will demonstrate.
1. Wire brush the material to remove surface rust and loose
scale.
2. Tack both ends of the plate to ensure metal to metalcontact.
3. Complete approximately half the weld, stop, remove slag,restart and finish the weld.
4. Remove all slag and spatter and submit the exercise for
visual inspection.
Metals and Engineering Industry
5.12AB Perform Routine Manual Metal Arc Welding
5. Break the weld and resubmit the exercise for internal
inspection.
6. Relocate the plates for further practice using all edges asshown.
7. Evaluate the weld exercise and complete the proceduresheet.
8. Submit your work for assessment.
Economy
Consumables and materials are expensive. Relocate plates for maximum
use. See chart (on earlier page) for suggested plate positioning sequenceto obtain four or more fillet welds from one material unit. Use all electrodes
down to a maximum stub length of 50 mm and return unused material tothe store.
Standards
Your work should have:
• correct alignment and assembly
• smooth regular weld contour
• angular distortion 0° to 5°
• a maximum of two significant weld defects per 250 mm of
weld length with an accumulative area of less than twice the
square of the plate thickness
• weld size 8 mm
• complete fusion for the length of the weld joint.
79
Metals and Engineering Industry5.12AB Perform Routine Manual Metal Arc Welding
Procedure sheet 3 - Fillet weld, single run horizontal
View A ViewB
Weld current data123
Electrode dataSize
TypeBrand Name
Electrode classification
Angles Lead Lateral
80
Material data
Type Low carbon steelThickness 10 mm
Assessment
Alignment and assembly
Angular distortionSurface finish
Weld size
Surface defects
Complete fusion
Workshop Safety
No. of units completed to standard
Complies:
Complies:
Complies:
Complies:
Complies:
Complies:
Complies:
Complies:
Metals and Engineering Industry5.12AB Perform Routine Manual Metal Arc Welding
Practical exercise 4 - Fillet weld, 3 run2 layer - horizontalAim
To use the fillet welding technique necessary to deposit an 8 mm three
run, two layer fillet weld to the requirements below.
Material
2 pieces low carbon steel 75 x 10 x 225
Consumables
Mild steel electrodes F4112 or E4113 at 160 to 175 amps approx.
Instructions
Your teacher will demonstrate.
1. Wire brush or grind the weld fusion faces to remove therust and mill scale.
2. Tack both ends of the plate ensuring metal to metal
contact with no gap. Tack only on the ends or side to bewelded.
3. Complete approximately half the first run, stop, remove
slag, and examine the weld profile.
4. Finish the run and subsequent runs using the sequence
illustrated with at least one staggered stop and start perrun.
5. Submit the exercise for visual inspection then fracture
the weld and resubmit it for internal inspection.
6. Relocate the plates for further practice using all edges asshown.
7. Evaluate the weld exercise and complete the proceduresheet.
8. Submit your work for assessment.
81
82
Metals and Engineering IndustryS.12AB Perform Routine Manual Metal Arc Welding
Economy
Consumables and materials are expensive. Relocate plates for maximum
use. See chart (on earlier page) for suggested plate positioning sequenceto obtain four or more fillet welds from one material unit. Use all electrodes
down to a maximum stub length of 50 mm and return unused material tothe store.
Standards
Your work should have:
• correct alignment and assembly
• smooth regular weld contour
• angular distortion 0° to 5°
• a maximum of two significant weld defects per 250 mm of
weld length with an accumulative area of less than twice the
square of the plate thickness
• weld size 8 mm
• complete fusion for the length of the weld joint.
Metals and Engineering Industry
5.12AB Petform Routine Manual Metal Are Welding
Procedure sheet 4 - Fillet weld, 3 run 2 layerhorizontal
Weld current data
Amperage used
Run 123
Electrode dataSize
TypeBrand NameElectrode classification
Angles Lead Lateral
Material data
TypeThickness
Assessment
Low carbon steel10 cm
Complies
Workshop safety Complies
83
84
Metals and Engineering Industry5.12AB Perform Routine Manual Metal Arc Welding
Practical exercise 5 - Outside cornerfillet - horizontal
Aim
To deposit a multiple nm corner weld in the horizontal position using
fillet welding techniques to the requirements below.
Safety
Always wear safety glasses when chipping slag deposits away from theweld.
Materials
Material from the single or 3 run fillet (crucifixes) exercises or 2 pieces 25x lOx 225 111111 low carbon steel.
Consumables
Mild steel electrodes E4112 or E4113 , 3.25 m at approx 120-130 amps.
Mild steel electrodes E4112 or E4113 4.0 mm at approx 160-175 amps.
Instructions
Your teacher will demonstrate if required.
1. A-ssemble and tack plates using a suitable spacer to
maintain root gap.
2. Position the plates and deposit approximately 50 mm ofthe root run.
3. Examine the bead shape and penetration before
continuing the weld.
4. Completely fill the remainder of the weld using 3.2
diameter electrodes and a logical weld sequence.
5. Seal the reverse side with a 6 mm horizontal vertical fillet
weld.
Metals and Engineering Industry
5.12AB Perform Routine Manual Metal Arc Welding
6. Add additional plates as required and repeat the exercise.
7. Evaluate the weld exercise and complete the proceduresheet.
8. Submit your work for assessment.
Economy
Maximise the use of electrodes and return all unused material to the store.
Standards
Your work should have:
• correct alignment and assembly
• smooth regular weld contour
• angular distortion 00 to 5°
• a maximum of two significant weld defects per 250 mm of
weld length with an accumulative area of less than twice the
square of the plate thickness
• weld size 8 ~6mm
• complete fusion for the length of the weld joint
• full radius weld.
85
Metals and Engineering Industry
5.12AB Perform Routine Manual Metal Arc Welding
Procedure sheet 5 - Outside corner fillet horizontal
86
Weld current data
Amperage used
Material dataTypeThickness
Assessment
Workshop safety
Electrode dataSize
TypeBrand NameElectrode classification
Angles Lead
Complies
Lateral
Metals and Engineering Industry
5.12AB Perform Routine Manual Metal Arc Welding
Practical exercise 6 - Fillet weld horizontal
Aim
To fillet weld 3 mm low carbon steel sheet assembled in the horizontal
position to the requirements below.
Safety
• Always use tongs to position tacked and welded work.
• Never leave hot work unattended in the workshop.
Material
6 pieces low carbon steel 50 x 3 x 225 mm.
Consumables
Mild steel electrodes E4112 or E4113 2.5 mm at approx 85-95 amps.
Mild steel electrodes E4112 or E4113 3.25 mm at approx 110-115 amps.
Instructions
Your teacher will demonstrate. Students must attend this demonstrationbefore beginning the exercise.
1. Clean, assemble and tack weld at three locations for each
joint.
2. Use E4112 electrodes and stop each run at least once.
3. Weld both sides of the horizontal fillet.
4. Repeat the exercise with E4113 electrodes.
87
88
Metals and Engineering Industry5.12AB Perform Routine Manual Metal Arc Welding
Economy
Materials and consumables are expensive. use electrodes down to amaximum total length of 50 mm.
Standards
Your weld should have:
• correct alignment and assembly
• smooth regular weld contour
• angular distortion 00 to 50
• a maximum of two significant weld defects per 250 mm of
weld length with an accumulative area of less than twice the
square of the sheet thickness.
• weld size equal to the sheet thickness ::.~mill
• complete fusion for the length of the weld joint.
note
Watch for these points.
Distortion tack at regular intervals, assembly and 'fit up' of
cornerjoint.
Metals and Engineering Industry
5.12AB Perform Routine Manual Metal Arc Welding
Procedure sheet 6 - Fillet weld - horizontal
Outsidecornerweld
Weld current data
Amperage used
Material data
TypeThickness
Assessment
Workshop safety
Electrode dataSize
TypeBrand NameElectrode classification
Angles Lead
Complies
Lateral
89
90
Metals and Engineering Indust/)·5.12AB Perform Routine Manual Metal Arc Welding
Section 5 - Butt Weld Terminology andFaults
Aim
To learn the technical terms used for butt welds and to be able to identify
typical weld defects.
Activity
L Read and study the resource material following.
2. Complete the review questions.
3. Ask for assistance if the information is not clear to you.
4. Ask a teacher or your supervisor to check and sign your
Training Record.
5. On completion of this section you must attempt the test
on this topic and reach the required level of competence
before proceeding to the next section.
Safety
Wear the proper clothing to protect your skin and eyes.
Do not·try to take short cuts or risks
Metals and Engineering Industry5.12AB Perform Routine Manual Metal Arc Welding
Butt weld terminology and faults
In this section you will learn about the different types of butt welds and
how to identify some of the faults which can occur in butt welds.
Butt welds are used to join metal products such as sheet, plate, rolled and
pressed sections. This type of joint has the advantage of giving high strength
without changing the profile of the structure.
Industrial uses for butt welds include:
• boiler and pressure vessel construction
• ship building
• earth moving equipment
• aircraft and submarines.
Butt weld joints can be designed for full penetration welding to give
maximum strength or for partial penetration welding in places where the
strength of the joint is not so important.
Weld preparation
Reinforcement
Weld components
Toe
Fusionzone
Root penetration
Parentmetal
Joint edges have to be prepared before plates are welded together. Joint or
edge preparation is essential for complete fusion and penetration.
91
Metals and Engineering Industry
5.12AB Perform Routine Manual Metal Arc Welding
\ ~ ; Root face: fa supporf fhe
~ _~_=========::~ fltst run of weld-JL- Roof gap: to allow complefeweld penetration
Weld preparations
On thick plate
use double V or U preparations. Less weld =less heat = less distortion.
U preparations
less weld metal than V preparations but aremore difficult to prepare.
V preparations
usually done by flame cutting or machining.
Single butt welds
back gouge and deposit a backing run formaximum strength.
Double butt welds and
need to balance joint to minimise distortion.multi-run fillet welds
{
.~
'j( )
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92
Plate thickness
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Metals and Engineering Industry5.12AB Perform Routine Manual Metal Arc Welding
Preparation types
There are several preparation types and details are given below.
Closed butt joint
This is used when the edges do not need preparing. They are placed
close together and single or double welded. The closed butt joint is
suitable for sheet up to 3 mm thick.
j~ -~-
Sr [ I~--~S
Open butt joint
This is used when the edges do not need preparing. They are separated
slightly to allow fusion of the full thickness of material. An open butt
joint is suitable for material up to 5 rom thick.
~mm ~ JI sr- -1L-'.S-2.S
Single V butt joint
This is commonly used on material up to 12 rom thick.o?2\/,---~?-~12m~
1.5mmm~JL f1.5 mm
93
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Metals and Engineering Industry
S.12AI3 Perform Routine Manual Metal Are Welding
Double V butt joint
This is used on plate 12 mm to 38 mm in thickness when both sides
are welded.
Single bevel butt joint
Used only when one member of the joint can be prepared as in the case of
a T joint.
~5°~Minimum",
15M~imu~JL
Single U butt joint
The single U butt is used as an alternative to single V butt joint.
~inimumr-\ 1-'
\ I r Radius5mm Minimum\1 ~ __ t
;'-1=V;r- -~-UPto 25mm. II t3 mm Maximum--i+-- 3 mm J
Metals and Engineering Indnstry5.12AB Perform Routine Manual Metal Arc Welding
Double U butt joint
This is used on material over 2S mm thick where welding can bedone from both sides.
iO~ Minimum
___ "/_1_r -===RadiUS 5 mmMitmLl====---"~L ;Up to 25mm
3 mm Maximum L 3 mm r
When you need to butt weld two sections of different thickness, you should
taper the thicker one to match the other. The length of the tapered sectionshould be at least three times the difference in the thickness between the
plates. This type of butt weld is used to join dished ends to pressure vessels.
Uneven section" butt joint
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Metals and Engineering Industry
5.12AB Periorm Routine Manual Metal Arc Welding
Weld defects
Common weld defects are detailed below.
Excesspenetration
Definition Too much weld metal extending through the root of the weld .
•••••• --- u u'-etration
Causes are:
• incorrect preparation
• amperage too high
• incorrect welding technique.
Incomplete penetration
Definition Failure of the weld metal to extend into the root of a joint.
7
S'
Causes are:
~.....:-..;:,." " .;:..::- :'-':.~"
",:.,
---------Incomplete penetration
~., .
..•- .
•••••• M'.'1·••·-'··-
// .• "_;1
96
• incorrect preparation
• amperage too low
• arc length too long.
Metals and Engineering Industry
5.12ABPerform Routine Manual Metal Arc Welding
Lack of fusion
Definition Incomplete fusion between weld metal and weld metal or weld
metal and parent metaL
)
Lack of fusion
Causes are:
• not enough amperage
• incorrect joint preparation
• incorrect welding technique.
Inclusions
Definition Slag or other foreign matter trapped during welding.
Causes are:
• faulty joint preparation
• not enough amperage
• poor cleaning of prior runs.
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Metals and Engineering Industry
5.12AB Perform Routine Manual Metal Arc Welding
Porosity
Definition A group of gas holes in the weld metal.
Porosity ~., '. ..,":.'? O';'~<".. ,':. '~'...
• ~~t'
Causes are:
• damp or old electrodes
• composition of parent metal
• incorrect electrode type.
Cracking
Definition Discontinuity produced from tearing of the weld metal while
in a plastic condition when hot or a fracture when cold.
HAZ cracking
Causes are:
• insufficient weld deposit
• insufficient pre-heat
• incorrect electrode.
Metals and Engineering Industry5.12AB Perform Routine Manual Metal Arc Welding
Undercut
Definition A groove or channel in the parent metal at the toe of the weld.
Causes are:
• too much current
• welding too fast
Undercut
• incorrect welding technique.
Overrall
Definition A section of unfused metal extending past the toe of the weld.
~verrOI1~w/ove~OIl
Causes are:
• electrode too large
• welding speed too slow
• incorrect electrode angle.
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Metals and Engineering Industry5.12AB Perform Routine Manual Metal Arc Welding
Misalignment
Definition Any variation from line or dimension of a welded joint.
Misalignment
Causes are:
• incorrect weld procedure
• careless preparation
• too few tack welds.
Incompletely filled joint
~ ~comPletelY filled joint
~.=- -~~~----(
100
Causes are:
• not enough weld metal
• welding too fast
• too few beads.
Metals and Engineering Industry
5.12AB Perform Routine Manual Metal Arc Welding
The principle of expansion andcontraction in a metal
Metals expand when heated and contract when cooled. For example, a
piece of low carbon steel, if not restrained in any way, will increase its
dimensions in all directions for every degree Celsius the temperature rises.
On cooling, the steel will return to its original size.
Angular distortion
There is distortion when unequal contractional forces cause angular changein the parent metal position.
j Outward movement~ caused by expansion
i
Inward movement
caused by contraction
Transverse distortion by butt weld
6 4 2 '3 5 7
Tack weld sequence
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Metals and Engineering lndustryS.12AB Perfonn Routine Manual Metal Arc Welding
Practical exercise 7 - Butt weld, flatsheet steel
Aim
To deposit single run butt welds in the flat position on 3.0 mm low carbonsheet steel.
Materials
4 pieces 40 x 3.0 x 150 mm low carbon flat bar.
Consumables
Mild steel electrodes E4112 or E4113 2.5 mm at approx 85-95 amps.
Mild steel electrodes E4112 or E4113 3.25 mm at approx 110-115 amps.
Instructions
Your teacher will demonstrate.
1. Assemble and tack weld sheets using the sequenceillustrated.
2. Position the plates with a sligh t slope and weld
approximately 50 mm of the joint.
3. Examine weld profile and penetration before completingthe weld.
4. Complete the weld and submit for inspection.
5. Cut sheets and relocate for further practice as illustrated.
6. Evaluate the weld exercise and complete the proceduresheet.
7. Submit your work for assessment.
Metals and Engineering IndustryS.12AB Perform Routine Manual Metal Arc Welding
Economy
Cut and relocate sheets for maximum use. Return all unused material to
the store.
Standards
Your work should have:
• correct alignment and assembly
• smooth regular weld contour
• weld penetration for a minimum of 20% of the weld length
• angular distortion 00 to 50
• a maximum of two significant weld defects per 250 mm of
weld length with an accumulative area of less than twice the
square of the plate thickness.
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Metals and Engineering Industry
S.12AB Perlorm Routine Manual Metal Arc Welding
Procedure sheet 7 - Butt weld, flat sheet steel
Weld current data
Amperage used
1.6mm 3.0mm
Electrode data
Size
TypeBrand nameElectrode classification
Material data
Type
Thickness
Assessment
Workshop safety
110
Angles Lead Lateral