SHIELDED METAL ARC WELDING..."Shielded Metal -Arc Welding" or "SMAW". The process is performed...

SHIELDED METAL ARC WELDING

(SMAW)

Learner Guide

TABLE OF CONTENTS INTRODUCTION, OBJECTIVES AND PURPOSE STATEMENT PAGE 1 PROGRAMME 1 SECTION 1 - THE SMAW PROCESS - "AN INTRODUCTION" PAGE 3 SELF-TEST EXERCISE 1 PAGE 6 SECTION 2 - BASIC EQUIPMENT PAGE 8 SELF-TEST EXERCISE 2 PAGE 18 PROGRAMME 2 PART 1 - HAZARDS WITH SMAW PAGE 21 SELF-TEST EXERCISE 3 PAGE 25 PART 2 - PERSONAL PROTECTIVE EQUIPMENT PAGE 27 SELF-TEST EXERCISE 4 PAGE 30 PROGRAMME 3 - WELDING TECHNIQUES - PART 1 SECTION 1 - INSPECTION OF EQUIPMENT AND PREPARATION OF WORK AREA PAGE 33 SELF-TEST EXERCISE 5 PAGE 36 SECTION 2 - SETTING UP OF TYPICAL WELDING MACHINES PAGE 38 SELF-TEST EXERCISE 6 PAGE 41 SECTION 3 - BASIC WELDING TECHNIQUES 1. STRIKING AN ARC PAGE 43 EXERCISE NO. 1 PAGE 45 2. LAYING STRINGER BEADS PAGE 48 EXERCISE NO. 2 PAGE 50 3. CHIP, CLEAN AND READ WELDING BEAD PAGE 52 EXERCISE NO. 3 PAGE 55 4. SQUARE BUTT-JOINT PAGE 56 EXERCISE NO. 4 PAGE 59 5. BUTT-JOINT WITH SINGLE "V-GROOVE" PAGE 61 EXERCISE NO. 5 PAGE 65 6. "T-JOINT" PAGE 67 EXERCISE NO. 6 PAGE 69

CONTACT DETAILS: https://techav.co.za

[email protected]

https://techav.co.za/

mailto:[email protected]

Back to Table of Contents 1

INTRODUCTION This learning aid, consisting of a workbook (Learners guide) and video programme, has been designed to assist you to learn the BASIC SKILLS involved in "shielded metal arc welding". OBJECTIVES (Purpose ofthis material) This series of programmes serves to assist you, the learner, in achieving a "Learnership" in any of the engineering fields where metal-arc welding is stated as being a "unit of learning". PURPOSE STATEMENT (What you will learn) During this series you will learn:

o To identify, by name, the principle components and accessories that constitute the "shielded metal arc welding" apparatus.

o To recognise and deal with the hazards associated with shielded metal arc welding processes.

o To set up welding equipment and the work area. o To use arc-welding equipment with mild steel work-pieces.

LEARNING ASSUMED TO BE IN PLACE (What you should already know)

o A working knowledge of Industrial Safety. o Identify basic metals and materials associated with industrial environments. o Basic knowledge of electricity and electrical circuits.

LEARNING OUTCOMES (What you will be able to do after completion ofthis series)

o Prepare a given machine for "SMAW' welding operation. o Prepare the work area for safe operation. o Perform basic "down-hand" (flat position) arc welding processes. o "Read" a weld and determine corrective action.

LEARNERS INSTRUCTIONS (How to use this Learning Aid) Step 1 - Read the Resource Notes and follow the written instructions. Step 2 - View the relevant video section (where applicable). Step 3 - Complete the relevant "Self-Test Exercise" (when applicable). Step 4 - Perform any practical exercise. Step 5 - Have your Facilitator/Mentor check your work.


SHIELDED METAL ARC WELDING PROGRAMME 1 (THE SMAW PROCESS - AN INTRODUCTION)

PART 1 THE BASIC SMAW PROCESS In this programme you will learn the basic principles of "shielded metal arc welding". You will learn about how it works and what the main components are in a typical SMAW set. When you have completed this programme you will be able to:

o Describe the principles of arc welding. o Describe the SMAW process. o Identify by name all the major components in a typical system. o Describe the 3 basic types of welding machines. o Read and interpret basic "nameplate information". o Identify and describe types of welding leads. o Identify covered electrodes. o Identify basic welders' tools.

BEGIN BY READING THROUGH THE FOLLOWING NOTES.


RESOURCE NOTES PROGRAMME 1 - PART 1

SECTION 1: WHAT IS ARC WELDING? 1. WHAT IS ARC WELDING? The term "arc-welding" describes the process of fusing metal sections together by way of heat generated with an electrical spark, or "arc". The process that will be described in this series of programmes is known as "Shielded Metal-Arc Welding" or "SMAW". The process is performed manually, that is, a welder has to physically manipulate the welding action, by "hand". For this reason the process is also known as "Manual Metal Arc-Welding" or MMAW. SMAW is mostly associated with the welding of "mild carbon-steel", low alloy steel and certain other "weld-able materials". In essence the process of arc welding relies upon an electric current flowing in a "closed circuit" or "loop". The current is caused to jump across a gap, created between an electrode and the "work", or the "base metal" (sometimes referred to as "parent metal"). When a current jumps over a gap a "spark" occurs and heat is created. The temperature reached inside an arc is in the region of 6000˚C. Metal in direct contact with the arc melts and fusion takes place within the spark area. An "electrode", also known as a welding-rod (or welding wire), made from the same (or similar) material as the base metal (work piece), is used to direct the current onto the base metal. The electrode burns away (melts) and deposits metal into the welding joint. Welding rods (electrodes), used with SMAW processes, are coated with "flux" that burns away during the "arcing" process. HOW DOES THE "SHIELDED METAL ARC PROCESS WORK?" The temperature generated within the arc is sufficient to cause most metals to melt. The most commonly welded metal, using the SMAW process, is "mild-steel" (also called "low carbon-steel). Within the arc "fusion" occurs between the "base-metal" and the electrode. The electrode, which has a metal core of similar metal to the base-metal, "melts" into the weld adding "filler" into the joint.


In the "fusion process", the flux coating that surrounds the electrode, burns away and in this way creates a "shielding gas" which envelopes the "molten metal". This "shield" of gas prevents oxygen, in the atmosphere, from entering the material. In other words the gas prevents the metal from "oxidising" whilst it is in the molten state. Flux also mixes with the molten material causing "impurities to rise to the surface of the weld-bead. A hard "temporary protective layer" known as "slag", forms upon the surface of the weld-bead as the metal cools. Slag protects the weld during cooling, but has to be removed before further welding can take place upon an existing bead. A "chipping hammer" is used for removing slag.

SECTION-2 BASIC EQUIPMENT A typical SMAW "welding outfit" consists of the following:

o Welding machine which is the "Power source" for arc welding. Depending on the machine design, a current. between 50 amps and 600 amps, will be created, and delivered to the machines' "output connections".

o "Welding leads" (cables). Carry the "output current" from the welding machine. There are two "welding-leads" required in the system namely: A "work-lead" also called a "ground-lead" that connects the "work" to the

welding machine. An "electrode-lead" that carries current from the machine to the electrode.

o "Electrode holder" - The part that the "Operator" uses to control and manipulate the electrode.

o Electrode (welding rod) - This is the "consumable" portion of the equipment. In SMAW processes, the "electrode" is a metal rod (wire) that is surrounded, or coated, with a layer of "flux", The metal in the electrode is of similar composition as the "parent metal".

Other items known as "welding accessories" will be discussed in later sections,


NOW VIEW VIDEO SMAW NO. 1 – PART 1.



SELF-TEST NO. 1 THE SMAW PROCESS

INSTRUCTIONS Complete the following exercise without reference to your notes or the DVD. When you have completed the exercise check your answers / responses by:

o Referring to your notes. o Reviewing the video material. o Asking your Facilitator / Mentor.

QUESTIONS YES NO

1. What do the letters “SMAW” stand for? ANS: _________________________________________________

2. List the main components of a SMAW set-up i) _______________________________________________ ii) _______________________________________________ iii) _______________________________________________ iv) _______________________________________________

3. What 3 names are sometimes used for the welding-lead that connects the machine to the work-piece? a) _______________________________________________ b) _______________________________________________ c) _______________________________________________

4. What is the other welding-lead called? ANS: _________________________________________________

5. What are the two basic tools required by a welder? i) _______________________________________________ ii) _______________________________________________

6. Give 2 purposes for the “flux coating” on a covered electrode. i) _______________________________________________ ii) _______________________________________________


7. Why is slag important? ANS: _________________________________________________

READ NOTES SECTION 2.


RESOURCE NOTES PROGRAMME 1 - SECTION 2

BASIC EQUIPMENT 1. WELDING MACHINES Various types of welding machines are available, made in assorted sizes and by many different "manufacturers". The selection of a particular machine is generally made upon the type of work to be done. There are 3 "kinds" of machines used with SMAW processes and these are:

1) AC or "alternating current" machines. 2) DC or "direct current" machines. 3) AC / DC also known as "Combination machines".

AC MACHINES These are the most "basic" of welding-machines used in many factories, plants, farms and "home workshops", because of their simple and inexpensive construction. Input power is supplied from the "shop mains supply" and machines are available for single-phase input and 3-phase input. The "output" from an AC machine is "alternating current". Current output is rated in "amperes" (AMPS). For arc welding purposes we require currents ranging between 50 up to 600 amps depending on "electrode sizes" and "metal thickness". Simple machines (designed primarily for "home use") are fitted with "tapping-points" to which the welding-leads are attached. One of these points will be the "Work or Earth" point. The other points are used to attach the "electrode- lead". Each "electrode point" will provide a fixed output thus providing a variety of "amperages". Professional machines usually have "adjustable output controls" which provide the means to set the desired output (amps) by altering the position of a switch, lever or a rotating control. NOTE: If you are not familiar with electrical theory and terminology, do not worry at this time. Just be aware of the "differences" from the "operating" point of view. Any welding machine will be "rated" according to its "maximum output" in AMPS. For example a "200 amp machine" will produce a maximum of 200 amps. The controls of AC welding machines are usually simple.


DC MACHINES A DC machine produces "direct current" to the welding-electrode. DC is a more "stable" current than AC and is particularly suitable for welding thin steel plate and certain "non-ferrous" metals. One of the major advantages of DC machines is that the welder (Operator) has the choice of changing the output "polarity" from "straight" to "reverse". Explanation: Direct Current (DC) flows from a "negative" connection and completes its "circuit" at the "positive" connection. When the electrode is connected to the "negative" (-) output connection of the machine then the system is considered as being "straight polarity". In such a connection the current flows from the work to the electrode. The electrode in this case is "negative" and we call this circuit "DCEN" (direct current- electrode negative). If the welding leads are switched around, that is if we connect the electrode lead to a Positive (+) output connection, then the electrode becomes "positive" and the flow will be from the electrode to the work. Such a circuit is called "DCEP" (Direct current -electrode positive).

Straight Polarity Reverse Polarity

DCEN DCEP

On some DC machines simply operating a switch (polarity switch) from "straight to reverse" can change the current "polarity". On other types of machine it is necessary to (physically) swap the welding-leads at the machines' "output-terminals" in order to switch polarity. Other terms used with DC connections are: DCSP meaning DC Straight Polarity (DCEN). DCRP meaning DC Reversed Polarity (DCEP). DCEP results in deep weld penetration and is suitable for thick metal joints. DCEN results in fast melting of the electrode but less heat into the base metal. DCEN is therefore more suitable for welding thin-plate.


NOTE: A machine must always be switched OFF before the polarity is changed. AC / DC MACHINES (Combination Machines) These machines combine both AC and DC outputs into one single unit. The operator (Welder) can select which type of current he / she requires for a particular job. In addition the DC polarity can be switched for DCEN and DCEP. These machines are obviously more expensive than single function machines. MACHINE "NAME-PLATES" OR "MANUFACTURERS RATING PLATES" A lot of information can be obtained by reading the manufacturers' "nameplate". A nameplate may be fitted to any part of the machines' casing. In some instances the nameplate information may be provided on a "decal" (sticker). The important information that should be given is:

o The "INPUT' power requirement in terms of volts and the "frequency" (cycles).

o The "OUTPUT' in terms of, current type (AC or DC), "rated output current", "operating voltage" and "open circuit voltage".

o The "Duty Cycle". INPUT DATA (PRIMARY SIDE) Details must provide the user with information on:

o Power-supply voltage and phase. (single phase or 3 phase). o Cycles (frequency) in Hz (Hertz). In SA we operate on 50 Hz. o Current draw (amps) - The maximum current that the machine will draw

whilst operating at full load. OUTPUT DATA (SECONDARY SIDE) Details regarding the outputs will be given here such as:

o Maximum rated "amp" output on each setting. For example, an AC / DC machine may offer a certain output when switched to its AC function , but a different output when switched to its DC function.

OTHER INFORMATION There are two terms that you will see on virtually all machines' "name-plates", namely:

1) Duty Cycle and 2) Open Circuit voltage or OCV.

Let us explain these important terms.


DUTY CYCLE A duty cycle is a "rating" given to any welding machine and it refers to the period of time that the machine can be operated at FULL LOAD. Most machines generate "internal heat" during operation as a result of inductive electrical resistance. The greater the output (amps) the greater, and the faster, will be the amount of heat generated. If a machine is operated at its maximum output for an excessive amount of time then serious damage will occur. The welder must be aware of the machines' limitation in terms of time used. The duty cycle of any machine is given as a "percent factor" in terms of a "ten minute" period of time. For example if the "duty cycle" is given as 60% (common rating) then the machine can be operated for 60% of 10 minutes at maximum load. In other words it can be operated for 6 minutes. The remaining 4 minutes (6+4=10) are required for the machine to "cool". If a machine is operated below its maximum rated output then it can be operated for longer periods between cooling times, in other words the duty cycle is extended. You may find a welding current graph in the "operator’s manual" indicating the duty cycle at various current settings for that particular machine.

By way of an example we have included a "typical welding current graph".

Note that the example above indicates the Current graph for a machine with a 20% duty cycle at its max. output of 200 Amps. If the machine were to be operated at 100 amps then the duty cycle would be 100% or "continuous".

OPEN CIRCUIT VOLTAGE (OCV) This is the voltage (potential) available from the machine when it is switched-on but not operating (welding). Most machines have an OCV of between 50 to 80 volts,


which is sufficient to start an arc but low enough to reduce the risk of "electric shock" to an operator. With AC machines there has to be a small voltage available in order to maintain the arc. This is called the "closed circuit voltage" and is typically between 5 and 30 volts. 2. WELDING LEADS (CABLES) Welding leads must be very flexible (bend easily) and in order to achieve this the "conductor core" is made of very fine (thin) copper wire strands. Thousands of strands may be used in a large diameter cable. The copper conductor core is surrounded with heavy insulation. Cables must be large enough to carry the "electrical load" from the machine. Various cable sizes are manufactured and it is important that the correct size is fitted. Cable size is determined by the "cross sectional area" of the core (conductor) but in practice we usually select the cable according to the core "diameter". Another important consideration must be made according to cable length. As the cable length increases so will the "resistance". Below is a table indicating common cable sizes and the size factors for various lengths.

CURERNT CAPACITY (LOAD) IN AMPS

Load Size No. Lead Diameter (core)

Length In Metres 0 - 15

Length In Metres 15 - 30

Length In Metres 30 – 75

4/0 3/0 2/0 1/0 1 2 3 4

mm Load in Amps Load in Amps Load in Amps

24.4 21.0 19.2 18.3 16.4 15.3 14.4 13.5

600 500 400 250 200 150 125

600 400 350 300 200 195 150 100

400 300 300 200 175 150 100 75

Table 1 - Welding Lead size / length recommendations


LEAD CONNECTIONS Welding leads must be "terminated" at their ends with suitable "terminals- connectors". Where a cable is connected to "tapping points" then the connector is simply a "lug-type". Lugs are usually "crimped" to the cable. Some machines are fitted with "quick-connectors". The leads for such machines must therefore be fitted with appropriate connector pins, usually of the "bayonet" coupling design (twist to lock). Ground cables, at the "work-end", are usually fitted with lugs. The lug is then attached to any suitable device, such as a spring-clamp for attaching to the work or metal structure. 3. ELECTRODE HOLDERS Without this part it would be impossible to direct the electrode into the joint to be welded. The electrode holder is very heavily insulated for safety reasons. Any damage to the insulation of an electrode holder greatly increases the risk of "ELECTROCUTION". A common type of holder feature "spring loaded jaws". The electrode is gripped between these jaws. All electrodes must have a "bare metal" section, free of flux, onto which the electrode jaws make "electrical contact". The "electrode lead" terminates at the jaws of the holder. A special locking device ensures that the "conductor core" is held securely beneath the insulated handle of the holder. The holder must be held only by the "insulated handle", and always with a "gloved hand". Safety note: If you can see copper strands at the electrode holders handle then DO NOT OPERATE the equipment. Report this to your Supervisor or have a qualified electrician attend to repairs. 4. ELECTRODES There are numerous types of electrodes, each manufactured to exacting standards by companies all over the world. The success (or failure) of any weld is, to a large degree, dependant on the electrode selected, or "specified" in the "welding procedure". Arc welding electrodes are identified under the AWS numbering system (American Welding Society).


In this training series we are concerned only with electrodes fitting into the "mild- steel" category which fit into the AWS system under the specification A5.1. The "size" of an electrode is determined by (measuring) the diameter of the "wire" (the bare section). Common (for general-purpose) sizes: 2.0mm, 2.5mm, 3.15mm and 4mm. When specifying an electrode we need to give the "wire-size" and then the AWS specification. The most commonly used electrodes in maintenance and repair of mild-steel structures are listed below. There are many other types of electrodes available for other types of metals and you will need to ask your Facilitator or your electrode supplier for information about welding other metals. E6010 - This electrode is used when welding with DCEP (Reverse Polarity). This type provides for deep penetration into thick metal, and can be used where the parent metal is difficult to clean. (Dirty, rusty or painted). E6011 - This is used for both AC and DC operations on thick metal. E6013 - This is a "general-purpose electrode". Is used where the weld appearance is important and where "medium penetration" is required. Suitable for both AC and DC. E7018 - Also known as a "low hydrogen", this electrode can be used with AC and DC. This electrode is used for "high quality" welds such as needed on pipes. Low hydrogen electrodes must be kept DRY as moisture in the flux will increase the "hydrogen content" and severely weaken the weld. These rods must be kept in a "drying oven" once the pack has been opened. WHERE TO LOOK FOR ELECTRODE IDENTIFICATION (And what you're looking at) Most electrodes, from 2mm up in size, will have the AWS number printed on the flux at the "bare-wire end". This identification, as well as other information, will also be printed on the "packaging label". In the AWS system an electrode is given the letter "E" followed by a 4 or a 5 digit numeral. A typical number is E6013, (but you will normally only see "6013" on the electrode). "E" indicates that it is an "electrode". The first two numbers of a four-digit number, or the first 3 numbers of a five-digit number, indicate the "tensile strength" (in "thousands of pounds per square-inch") of the weld that the electrode will produce. In other words an "E 60xx" numeral will produce a weld with a tensile-strength of 60,000 psi.


The second to last digit indicates the welding position, for example Exx1x is for all positions. Exx2x means that the rod is for use in "flat" (down-hand) and "horizontal position" welding. Exx3x means that the rod is only suitable for "flat position" welding.

The last two digits, in combination with each other, refer to both the flux composition and the type of current that should be used.

CURRENT TYPE AND COVERINGS The following "last two digits" on the electrode identification indicate:

Last 2 digits Use Current Type Flux Covering

Exx10 DC + (DCEP) Organic

Exx11 AC or DC- (DCEN) Organic

Exx12 AC and DC- Rutile

Exx13 AC and DC- and DC+ Rutile

Exx14 AC and DC- and DC+ Rutile, iron powder (30%)

Exx15 DC+ Low hydrogen

Exx16 AC or DC+ Low hydrogen

Exx18 AC, DC- or DC+ Low hydrogen, iron powder (25%)

Exx20 AC, DC- or DC+ High iron oxide

Exx24 AC, DC- or DC+ Rutile, iron powder (60%)

Exx27 AC, DC- or DC+ Mineral, iron powder (50%)

Exx28 AC or DC+ Low hydrogen, iron powder (50%)

Table - 2 The composition (chemical) of the "flux coating" plays a major part in the selection of a rod for metals to be welded. The purpose of the "flux" includes the following:

o Create a protective gas shield around the arc and the molten material. o Removes impurities from the molten metal. o Create a protective layer of "slag" to protect the weld as it cools.


o Improve the mechanical properties of the weld through the addition of certain elements.

o Some fluxes also provide additional "filler material".

The current (amp load) supplied to a given electrode is dependent on the wire diameter. Table - 2 offers a guide to wire size/current setting range.

Diameter (mm) Current (Amps) 1.6 20 – 40 2 40 – 80

2.5 60 – 95 3.15 110 – 130

4 140 - 165 Table - 3

STORAGE OF ELECTRODES Electrodes must never be allowed to become "wet". Moisture present in the atmosphere will render most types of electrodes useless over time. Some electrodes, notably "low hydrogen" types, cannot be used after they have been exposed to the air for more than 15 minutes. As a rule electrodes are obtained in sealed (airtight) packets that protect them from the atmosphere. As soon as the packet has been opened the electrodes will be at risk of becoming damp. The correct way to store electrodes, after the packet has been opened, is in a "warming box" or "drying oven". Such a device may be as simple as a sealed cupboard with a small electric lamp burning inside to keep the air warm and dry. More elaborate "thermostatically controlled" ovens are used in some establishments. Using a "damp rod" will result in poor quality of your weld, including weakness. Damp rods may be "re-dried" by baking in an oven at the "specified temperature and for a specified time". (See manufacturers' instructions on packaging) 5. WELDERS TOOLS

The welder does not require many "hand-tools" in the process of welding. The primary tools are:

o A Chipping Hammer. o A wire-brush.

The chipping hammer is used to break off the hard (yet sometimes "brittle") layer of slag after the weld has cooled. If this slag is not removed then the next layer of weld will have slag trapped within it resulting in "inclusions". An "inclusion" causes mechanical "weakness" and "failure of a joint".


The wire brush is required to loosen and remove "stubborn" slag from a welding bead. The brush is also used to loosen and remove rust or other deposits on metal prior to welding. Spanners may be required for attending to welding cable terminals and for securing earth-clamp attachments. Pliers, usually of the heavy-duty variety and "tongs" are useful tools for manipulating work-pieces, especially if they are hot. Clamps of all types, especially the "locking types", are used extensively for securing work. A ball-peen hammer (approx. 750g - 1 kg) is a useful tool for "setting" purposes.

NOW VIEW VIDEO 1 - PART 2.



SELF-TEST NO. 2 BASIC EQUIPMENT

INSTRUCTIONS Complete the following exercise without reference to your notes or the video. When you have completed the exercise check your answers / responses by:


QUESTIONS YES NO

1. What are the 3 basic types of welding machines? 1) _______________________________________________ 2) _______________________________________________ 3) _______________________________________________

2. What "current range" is required for most SMAW operations? ANS: _________________________________________________

3. In DC terms, what is "straight polarity"? ANS: _________________________________________________

4. What does the term "DCEN" mean? ANS: _________________________________________________

5. What must you be sure to do before you change polarity on a machine? ANS: _________________________________________________

6. What are the main details, from the welder’s point of view, that you can read from a "name-plate"? i) _______________________________________________ ii) _______________________________________________ iii) _______________________________________________ iv) _______________________________________________

7. If a machine has a duty cycle of 20% at its maximum output, how long can it be operated before it has to cool? ANS: _________________________________________________


8. What factors in a "welding-lead / cable" determines the maximum current that it can carry? a) _______________________________________________ b) _______________________________________________

9. What should you always be wearing when you handle the "live" electrode holder? ANS: _________________________________________________

10. What does the size of an electrode refer to? ANS: _________________________________________________

11. How should electrodes be stored? ANS: _________________________________________________

12. List 4 tools that a welder should have available at the work station. i) _______________________________________________ ii) _______________________________________________ iii) _______________________________________________ iv) _______________________________________________

THIS CONCLUDES PROGRAMME 1. HAVE YOUR MENTOR / FACILITATOR CHECK YOUR WORK AND THEN MOVE ON TO PROGRAMME

2.


PROGRAMME 2 - SAFETY AND PERSONAL PROTECTIVE EQUIPMENT

INTRODUCTION In this programme you will learn about safety and personal protective equipment required during the process of "metal arc welding". When you have completed this programme you will be able to:

o Identify and name the hazards associated with SMAW. o Identify and describe the purpose of standard PPE for SMAW.

PLEASE MAKE SURE THAT YOU HAVE ACCESS TO VIDEO PROGRAMME SMAW-2 (SAFETY AND PERSONAL PROTECTIVE EQUIPMENT).

READ THROUGH THE FOLLOWING NOTES.



HAZARDS WITH SMAW The Primary hazards associated with ARC welding processes are:

1. Electric Shock. 2. Eye Flash or "Retinal Burn". 3. Flash or Arc-Burn. 4. Toxic fumes and gas.

1. ELECTRIC SHOCK It must be remembered that arc welding is only possible because of the presence of "electricity". Precautions must be taken to reduce the risk of shock as with any other "electrical apparatus". To avoid electric shock you should be observe the following "rules":

o Switch off a machine when it is not in use. o Place electrode-holders off the work when not in use. Do not leave them

lying on the ground, or on top of the welding machine. An electrode-holder stand is ideal for storing the holder.

o Keep all equipment dry. Damp (wet) equipment is a "killer". Dry all equipment if it is wet, but only do this with the machine ISOLATED from the input power supply.

o Do not stand on wet ground or floors when welding. Stand on wooden "duck-boards" or a rubber mat, especially if the workbench is made of metal.

o Wear only leather shoes (or boots) with "rubber-soles". o Do not touch the electrode with "damp gloves". Even gloves that are

"sweaty" from your hands will conduct current. o Do not touch the electrode and the "work" simultaneously, as current will

flow through your body. By the same reasoning, do not hold the electrode and the earth-lead at the same time.

o Connect the earth lead to "bright metal" in order to establish a proper electrical contact. Rust, paint and dirt should be removed from the work, or the earthing-point. Always connect the earth lead first, before you handle the electrode-lead.

o Do not make body contact with the work whist welding. Make sure that the "ground clamp" is as close as possible to the arc. If you get in between the ground and the arc then your body can become the "earth-path", with fatal consequences.

2. EYE-FLASH (RETINAL BURN) The electric "arc" from the electrode tip produces intense "visible light" as well as heat. Both "Infra-red" and "ultra-violet" light rays are generated in the arc. Looking


directly into an arc with "unprotected eyes" will almost certainly result in "permanent eye damage". Even the "reflected light" bouncing (flashing) from a wall or other surface can result in eye damage to anyone in the immediate area. A condition known as "arc-eye" is the "least" you can expect without using adequate protection from "flash". Arc-eye is a very painful and extremely uncomfortable condition much like having sand in your eyes. To prevent eye injury, follow these procedures:

o Always wear a "welders helmet' when welding. o Wear anti-flash goggles when you are in the vicinity of arc welding

operations. o Erect suitable "flash screens" around your work area to shield other workers

from the arc. o Do not "lift your visor" when striking an arc. Even the short duration of a flash

can result in "arc-eye". 3. FLASH BURN (ARC BURN) This is by far the commonest injury reported (and not reported) by welders. Flash burn is basically the same as "sun burn" and it affects any part of the body that is not covered. Flash burn can affect anyone within a 5 - 6 meter radius of the arc. To avoid flash burn practice the following:

o Roll down the overall sleeves in order to cover the arms. o Always wear "chrome-leather welding gloves". o Keep the shirt or the overall fully buttoned during the welding process.

Alternatively wear a "welder’s cape" that covers the upper chest and shoulders.

o Always wear your "welder’s helmet", or use a "welders mask". These not only protect your eyes but they also shield your face from arc rays.

o Do not weld when wearing "short trousers". Severe and painful burns to the thighs will be experienced. Always wear long pants, preferably "overalls" to protect your legs and thighs from arc-burn.

4. TOXIC FUMES AND GAS During the welding process, flux burns of the electrode and "fumes" are generated. Some fumes, depending on the type of flux used on the rods, can be "toxic" therefore adequate "ventilation" must be applied to the welding area. The use of "extraction units" (exhaust ducts) to carry off fumes is essential in some applications. Note that toxic fumes will be generated when welding "galvanised (zinc coated) steel", or materials containing lead, copper and cadmium.


Follow these precautions when welding: o Make sure that there is plenty of "fresh air" surrounding your work area.

Never weld in a "confined space" where there is no fresh air entering or flowing.

o Use a "fume extractor" (exhaust vent) when welding at a "welding bay" (indoors).

o Read the safety / health warnings provided on the packaging of electrodes and follow the advice and warnings given regarding fumes.

GENERAL SAFETY CONSIDERATIONS The previous 4 headings covered the primary hazards associated with arc welding. The following considerations must also be taken into account. Naturally your "local conditions" will also dictate certain safety rules as well. FIRE PREVENTION The process of arc welding is one classified as "hot work". The production of heat, sparks and the high temperatures associated with the process naturally poses a "fire risk". Welding should not be carried out in any area where ignitable materials or substances exist. For example one must not cause a spark to occur in a "fuel store", for obvious reasons! The welder must do everything possible, before welding, to ensure that there are no "flammable" materials or substances in the immediate area of work. Wherever possible move the work to a "safe location". Where this is not possible make the area "fire-safe" using whatever means available. Always make sure that a fire extinguisher (applicable to the material in the area) is nearby whenever you are welding. Where necessary, have someone stand "fire-watch" for you until you have completed the work. Consult your safety engineer, or fire officer if you are in doubt about the materials or substances in an area. CONTAINERS Owing to the potentially "explosive" nature of certain containers it is extremely "hazardous" to attempt any welding or other "hot work" operation on "unknown containers". Drums, tanks, barrels, silos and other "vessels" may have previously contained flammable or toxic substances. The heat from welding can ignite the "residual fumes" in such vessels or promote the release of toxic fumes. NEVER attempt welding on any vessel until you have obtained clearance from your safety officer or "risk control engineer".


ENGINE DRIVEN WELDING MACHINES Engine powered welding units are very commonly used, especially on construction sites and places where there is no "mains power". The following precautions should be observed when using such equipment:

o Never operate the machine inside a closed space, as you will run the risk of "carbon monoxide poisoning".

o Wherever possible operate the machine in an "outside" environment. o Use an "exhaust extractor" if you have to operate the unit inside. o Do not weld directly alongside the unit as fuel (fumes) may ignite. o Make sure that you have been given proper instruction on the correct and

safe operation of the machine. Follow the operators' manual at all times. ACCIDENTAL BURNS It must always be noted that welding involves HEAT and that heat results in HOT METAL. Metal might not look hot, but you'll certainly know it IS hot if you pick it up in your bare hands! The basic rule is this: Always "assume" that metal is hot inside the welding bay or in a welding area. Don't touch any metal object with your bare hands. The burn resulting from hot metal is not only painful but can result in "secondary infection". Even the little "stinging burns" received from the odd spark or piece of "slag" hitting your skin can turn "septic" if not properly treated. Do not wait until the burn has turned "bad", get immediate treatment! Note! If you are burnt, no matter how "minor', make sure that you get treatment (first aid).

NOW VIEW THE VIDEO SMAW 2 – PART 1.



SELF-TEST NO. 3 HAZARDS



QUESTIONS YES NO

1. What are the 4 main hazards associated with SMAW? 1) _______________________________________________ 2) _______________________________________________ 3) _______________________________________________ 4) _______________________________________________

2. When you have finished using a welding-machine you must do what? ANS: _________________________________________________

3. Where should the electrode holder be placed when you need both hands to doother things? ANS: _________________________________________________

4. The most likely cause of an electric shock, during a welding operation, would be what? ANS: _________________________________________________

5. What 3 safety items are intended to prevent your and your work mates', eyes from "eye-flash"? i) _______________________________________________ ii) _______________________________________________ iii) _______________________________________________

6. What can YOU do to prevent "Flash Burns"? ANS: _________________________________________________


7. What is the most important factor regarding "respiratory safety" when you are welding? ANS: _________________________________________________

8. Name 4 metals/substances that will generate toxic fumes when you weld on materials that contain them. i) _______________________________________________ ii) _______________________________________________ iii) _______________________________________________ iv) _______________________________________________

9. Before you use an electrode it is wise to do what? ANS: _________________________________________________

10. What safety equipment should always be close by the welding area in the event of fire? ANS: _________________________________________________

11. When using an "engine-powered" welding machine you must place the machine where? ANS: _________________________________________________

12. Why is it considered dangerous to weld on or near "used containers"? ANS: _________________________________________________

13. If you receive a BURN whilst welding or handling hot metal, what must you do? ANS: _________________________________________________

PROCEED NOW TO PART 2.


RESOURCE NOTES PROGRAMME 2: PART 2 PERSONAL PROTECTIVE EQUIPMENT (PPE)

INTRODUCTION In the previous section we described the "potential hazards" associated with arc welding procedures. In this section we shall look at the "personal protective equipment" used in the process of "SMAW operations. PERSONAL PROTECTIVE EQUIPMENT The term "personal protective equipment" (or PPE) relates to the safety apparel or devices that YOU the welder should be wearing or using in the "normal course ofyour welding duties". Failure to wear, or use, PPE may not only result in "personal injury" but could also result in you being "liable for the medical costs and legal implications" as a result! That's a tough call! Let us look at, and discuss the PPE that is considered "mandatory" for arc SMAW processes. WELDING HELMET The "welders helmet', sometimes called a "Welding Mask" is a "multi-purpose" device, but its PRIMARY purpose is to prevent EYE INJURY. No Human being can look at a welding arc with his / her naked eyes, for more than a couple of seconds without being "blinded". Prolonged exposure (a few seconds) with the naked eye can result in "permanent blindness". Within the welders-helmet is a "visor", which is the "window' through which you must view the work. The visor contains the "filter-lens", a very dark glass, that "filters out" most of the harmful rays of the arc. There are various types and designs of welding helmets but the most common type is that with a "Flip up" visor. This feature allows you to raise the visor portion but still keep the "mask portion" over your face. The purpose of this is to allow you to see the weld after it’s been made, and to "chip" the slag off without fear of pieces hitting you in the eyes or face. A clear piece of glass, or plastic, in the mask section protects the eyes from flying particles. Some (modern) helmets contain a visor that automatically "shades down" from "clear to dark" as soon as the arc is struck. With such a helmet it is impossible to "forget to drop the visor" when you begin a weld. In front of the "filter-lens" is a sheet of clear material designed to prevent "spatter" from damaging the filter. This "spatter-shield" can be renewed when necessary and is less costly to replace than the filter-lens.


WELDING GLOVES The correct gloves, for arc welding, are in fact "gauntlets" and are made of special "chrome leather". Welding gloves are necessary for two reasons:

1. They protect the skin from "arc burn". 2. They offer "limited" insulation from "electric shock" (provided that they are not

wet!). A further factor is that they offer "limited protection" from accidental burns, however one should not make a habit of picking up "hot work" with gloved-hands. (Use tongs instead!) WELDERS APRON The welders' apron, made of "chrome-leather", offers protection from sparks and radiation, and also protects the clothing. The wearing of the apron, unlike the helmet and the gloves, is not considered "mandatory", but is recommended, especially if the task involves kneeling, sitting or lying under the work! A piece of hot slag dropping in your lap can cause a very nasty wound. SKULL CAP Sparks and "slag" have a way of getting in your hair, literally! Prevention is achieved by wearing a "skull-cap". Again we have a piece of PPE that is not mandatory but recommended, especially for "out of position welding". A note here: "Baseball caps" are NOT suitable for protecting your head from sparks or hot slag. Most "caps" are made from "synthetic fibres" (polyesters) that are NOT fire resistant, in fact they usually "melt" with heat. OVERALLS (COVER-ALL'S) As most tradesmen/persons generally wear "overalls" as a matter of course it is hardly necessary to mention these. However, we need to mention that only overalls made using "fire-resistant materials are suitable for the welder. SPATS AND SAFETY SHOES / BOOTS The purpose of spats is to protect your feet from hot slag or spatter. Spats are made of chrome leather and are worn over your shoes or boots. The wearing of spats does not mean that you should not wear your regular "safety boots or shoes".


NOW VIEW VIDEO 2 -PART 2.



SELF-TEST NO. 4 PPE



QUESTIONS YES NO

1. Name 5 items of PPE that are considered essential for most arc-welding operations: i) _______________________________________________ ii) _______________________________________________ iii) _______________________________________________ iv) _______________________________________________ v) _______________________________________________

2. What items of PPE offer protection against the following? a) Arc rays to the eyes: __________________________________ b) Skin burns: _________________________________________ c) Head and hair burn:__________________________________

3. Complete the statement: "Limited protection from electric __________________ is provided through leather welding _________________ providing that they are not ________________".

4. When you are chipping hot slag you should be wearing your, what? ANS: _________________________________________________

5. In order that you can see what you are doing whilst chipping you should raise the, what? ANS: _________________________________________________ _____________________________________________________


6. Apart from the PPE made specifically for "welding tasks" you should also be wearing what when you are welding? i) _______________________________________________ ii) _______________________________________________

THIS CONCLUDES PROGRAMME 2 HAVE YOUR MENTOR / FACILITATOR CHECK YOUR WORK

AND THEN MOVE ON TO PROGRAMME 3 -PART 1.


SHIELDED METAL ARC WELDING PROGRAMME 3 - PART 1

INTRODUCTION In this programme you will learn how to prepare your equipment and perform "basic" welding techniques. When you have completed this programme you will be able to:

o Inspect your equipment and prepare your work area. o Set up a typical arc welding machine in preparation for SMAW processes. o Strike an arc and create "weld buttons" with AC output. o Lay stringer-beads upon flat plate. (Including stopping and restarting the arc). o Chip welding beads and read a weld in order to establish corrective action.

PLEASE ENSURE THAT YOU HAVE ACCESS TO VIDEO SMAW-3 -PART 1 AND SMAW-3 -PART 2.


RESOURCE NOTES PROGRAMME 3 - PART 1 (SECTION 1)

INSPECTION OF EQUIPMENT AND PREPARATION OF WORK AREA In this section of the programme we shall cover some rather "obvious" points. The main purpose of spelling out these points is to do with "safety" and "good working practice". Follow the recommended procedures / practices and you will enjoy less hassle as you go about your task of welding. A) INSPECTION INPUT CONNECTIONS With the exception of "engine powered machines", most welding machines are supplied with power from "commercial electricity sources" such as "Eskom" (in South Africa). Common "voltages" are 220, 380 and 550 for most "industrial users". Welding machines may be "hard wired" into the building/factory / plant in which case there is no need for the welder to be concerned about which "point to connect to". Many machines however are "portable", meaning that they can be transported to any plant and "plugged in" to the local supply. When connecting a "portable machine" the following points must be noted:

o Check the "input requirements" provided on the "name-plate" (data plate) of the machine. This will give the details regarding the voltage value, frequency and amperage draw.

o Check that the "shop supply" (house supply) matches that of the machines' input requirement.

o Ensure that the input-lead and the plug (connector) are in good order. The connector must be firmly attached to the lead with no bare wires (cores) visible.

o The lead itself must be in good condition, without damage to insulation. There must be no "taped joints" or other "makeshift repairs" apparent in the lead.

o Do not switch on the power until all output connections have first been made. CHECK THE MACHINE (Physical condition) Welding machines are "notoriously neglected" pieces of equipment but this should not be the "norm". A good welder will make a habit of inspecting the machine, especially if that machine is "new to him". A qualified person MUST attend faults that could affect your safety, and the operation of the machine, BEFORE connecting the machine. Minor faults should be noted and reported for attention by the relevant maintenance personnel.


The following checks/inspection points should be made:

o The covers should be in position and all attaching screws in place. Missing screws and loose covers indicate that "someone has been tampering inside".

o Check that all ventilation ducts / screens / vents are clean and clear of debris such as rags, paper and plastic packets.

o All control devices such as switches, handles and connector points should be "intact" and clearly marked as to their "function". If you cannot read the "decals", and you aren't sure what a control is for, then it would be risky to use that machine.

o Check the incoming power lead connection. The connection must be secure, not floppy and loose at the machines' "entry point".

o If the machine has threaded "tapping points" then check that the threads are in good condition and that the tapping points are firm / tight.

o Make sure that the machine is DRY. If the machine is wet, (from standing in rain, mist or dew etc.) it must be dried off before connecting to the mains.

CHECK THE WELDING LEADS (Output connections) Welding leads must be in a SAFE condition before you attempt to weld. Unsafe leads have been the cause of many "incidents" some resulting in death! Do not underestimate the importance of the following checks (with the machine "disconnected" from its input).

o Inspect each lead along the entire length for any damage or wear to the outer insulation.

o Do not use a lead that has been "taped" or has a "makeshift join" in it. o Check that the connector lugs or "quick-couples" (depending on type) are

secure on both leads. o Check that the "Earth / Ground connector" is intact on the work-lead. o Check that both leads are firmly attached to the machine terminals (tapping’s

or couplings). o Make sure that the work-lead is attached firmly to the work or to the welding

table (as dictated by the set up) and that there is a "clean contact" to "earth". EXAMINE THE ELECTRODE HOLDER AND ELECTRODE The following must be assured in respect of the electrode-holder and the electrodes.

o Electrical contacts (jaws) of the holder must be "electrically sound", not pitted or burned.

o Check that the lead into the holder is secure and that no bare wire is visible. o Check that the insulation, both of the handle and at the "nose-pieces" is

intact and not cracked, broken or missing. o The holder must grip the electrode firmly. o The electrodes must be DRY. o The flux must not be chipped or flaking off the wire. o The electrode should not be "bent" (which cracks away the flux).


o The specified type and size electrode must be fitted. (to suit the work) B) PREPARATION: PREPARE YOUR WORK AREA Obviously this can be done as your first task when setting up. You may intend working inside a welding-bay or you may have to weld something "on site". No matter where the operation takes place the following should always be considered when "setting up".

o Where necessary, wipe or dry any water / moisture / liquid spills around the work area.

o Erect "Flash Screens" around the work area. o Remove any flammable matter from the area. o Ensure that the area has adequate "ventilation" (fresh air). o Where applicable, check that exhaust fans are running and that there is an

adequate flow of air through the "hood". o Remove all obstacles or debris that could otherwise cause you to slip, trip,

snag or fall whilst you are welding. o Position your welding machine in such a way that it is close enough for you to

access during the operation yet have adequate "ventilation" for cooling purposes.

o Check where the welding cables will be laying and set them in such a way that they don't become "hazardous".

NOW VIEW VIDEO-3, PART - 1 (SECTION 1).



SELF-TEST NO. 5 INSPECTION OF EQUIPMENT

AND PREPARATION OF WORK AREA. INSTRUCTIONS Complete the following exercise without reference to your notes or the video. When you have completed the exercise check your answers / responses by:


QUESTION (tick correct answer/s) YES NO

1. Before you connect a welding machine to the mains (input) you must do what? (Tick appropriate response) a) Ensure that the power matches the input requirement of the

machine. b) Test the power point for power. c) Call an electrician.

2. If you notice any faults on the welding machine you should do what? (Tick appropriate response). a) Repair all the faults. b) Report all the faults. c) Have a qualified person attend to the faults.

3. Welding leads (cables) must be checked for what? (Tick appropriate responses). a) Insulation damage. b) Makeshift connections. c) Security of connections at the machine. d) Good electrical connection to "ground". e) Colour of the insulation.


4. What checks should be made to an electrode holder? a) _______________________________________________

_______________________________________________ b) _______________________________________________

_______________________________________________ c) _______________________________________________

_______________________________________________

5. It is not recommended that an electrode is "bent", for what reason? ANS: _________________________________________________

6. When welding in an area where other workers are present you must place what around your work area? ANS: _________________________________________________

7. In order to reduce the risk of electrocution you should make sure that you work area is, what? ANS: _________________________________________________

8. Welding leads should be positioned in such a way that they, what? (Tick correct responses) a) Do not present a hazard. b) Won't be driven over by vehicles. c) Don't lie upon hot material

NOW MOVE ON TO SECTION 2.

READ THROUGH THE FOLLOWING NOTES.



SETTING-UP A TYPICAL WELDING MACHINE In this section of the programme you will learn how identify the basic "controls" of typical machines and how to set-up typical welding machines in preparation for SMAW operations. 1. WELDING MACHINE "CONTROLS" It is very important that you are familiar with all of the controls on the welding machine that you intend to use. The best way to familiarise yourself with the controls is to study the "Operators Manual" for the machine. With the exception of small AC transformers (home use welding machines) the following controls will generally be provided on the front face of a machine:

o An "isolation switch" or "isolator". This is usually a simple ON / OFF switch and is used whenever the need to shut down the machine occurs, for example, when changing the "polarity" on an AC / DC machine.

o A current "range-selector" (also known as the "coarse-setting") in the form of a large switch or lever. Used to select the indicated range of output (amps) between "high" and "low" range.

o Current "fine adjustment" in the form of a "lever" or a rotating control. Used to "trim" the output setting in small increments.

o Polarity switch -found only on DC or AC / DC machines. Usually a heavy-duty toggle switch marked with the words "Straight" and "Reversed". This switch is used to alter the flow direction of DC current (DCEN or DCEP) when welding certain types of materials.

o Current Selector -found only on AC / DC machines. Selects either AC or DC output.

2. TYPICAL MACHINE SET-UP The setting up of any welding machine should always be done according to the "Manufacturers Specifications" which will be detailed in the "Operators Manual" or on a "decal" on the machine itself. AC TYPE MACHINES (SMALL UNITS) Single-phase (220 volt) machines are usually produced for "jobber" type operations having a duty cycle of around 25% and a maximum output of around 140 amps. Typically these machines are "oil cooled" and should be used in ventilated places to ensure that they do not overheat. The basic procedure for setting up the AC machine is as follows:

o Carry the machine (if applicable) in an upright position to prevent oil spillage from the "breather-vent".


o Place the machine on a dry and level surface (usually the floor or ground) close to the work area.

o Ensure that a convenient power point is in the vicinity (220 volt socket) and that the input lead reaches this. It may be necessary to use an extension-lead in which case make sure that this is in a safe condition and rated to carry at least 16 amps over 25 metres.

o Connect the "Work / Ground / Earth" lead to the machines' "Earth Terminal connection" and secure the nut firmly using a correctly fitting spanner. Do not over-tighten this nut as this action can break the internal connection.

o Connect the "Ground lead" to the work. o Connect the electrode lead to the "electrode terminal connection" on

machines that have adjustable outputs, or o Connect the electrode lead to the desired "tapping-pin / stud" for the output

required. o Set the desired output (amp) using the current-control lever or handle. o Select the appropriate electrode (type and size) and fit this into the electrode

holder. Ensure that the bare wire is gripped in the contacts. o Place the holder in such a place that it is NOT left on top of the work. o Check all connections and then plug the input lead into the power point and

switch on. THE BASIC PROCEDURE FOR SHUTTING DOWN IS AS FOLLOWS

o Place the electrode holder away from the work, and NOT on top of the welding-machine!

o Switch off (isolate) at the power point and disconnect the plug. o Disconnect the work-lead and coil-up both welding leads. Some machines

may have brackets attached for storing the leads. o Return the machine to its storage area.

AC MACHINES 3-PHASE INPUT The basic procedure for setting up is similar to the single-phase set-up described earlier. Many 3-phase machines have "Forced Draft Cooling", meaning that a "cooling-fan" is used to force air across the internal parts. The fan will only operate whist the machine is switched on at the isolation switch. The following points must however be observed during set-up and operation.

o After inspecting the machine for defects (see part 1 of this programme) transport it to the work site where applicable.

o Place the machine in such a position that the welding leads will extend, without being stretched, to the furthermost part of the work to be done.

o Ensure that the input lead (power) is capable of reaching the power connection point.


o Ensure that the power connection point is of the appropriate type and voltage. Check the "input data" on the machines' name-plate for this. Do not connect at this time.

o Connect the welding leads to the machines connection points making sure that, when AC current is selected, the "work lead" is connected to the "Earth / Ground / Work" connection.

o Connect the work / ground lead clamp to the work-piece ensuring a "clean electrical connection".

o Decide at this time what size and type of electrodes will be required for the material to be welded. Fit an electrode into the electrode holder and set this aside off the work.

o Check that the "isolation switch" (on / off switch) is set to the OFF position. o Set the "range setting" (coarse setting) to the desired range. For example, if

you require a 100 amp output set the course setting to the 50 - 140 amp position (this range may be different on other machines).

o Connect the main supply plug to the power point and connect the power (switch on).

o Switch on the machine at the isolation switch only when you are ready to begin welding.

DC MACHINES The setting up procedure for a DC machine varies very little from the AC machine. The most prominent difference is the "POLARITY" setting. Set the "polarity" to the desired state before you switch on. This usually involves connecting the welding leads to the relevant + or - output terminals to obtain either DCEP or DCEN. NEVER alter the polarity with the machine running. AC / DC (Combination machines) Again the general procedure is very similar to both types already mentioned. The following "extra observations" must be made:

o Attach the welding-leads to the relevant outlet sockets. Some AC / DC machines have different outlets (output connection points) for their AC and DC functions.

o Set the current selector to either AC or DC output, before switching the machine on.

NOW VIEW VIDEO -B3, PART 1(SECTION 2).



SELF-TEST NO. 6 WELDING MACHINE - STANDARD

CONTROLS AND SET-UP INSTRUCTIONS Complete the following exercise without reference to your notes or the video. When you have completed the exercise check your answers / responses by:


QUESTIONS YES NO

1. When using a welding machine for the first time what should you do before you start? ANS: _________________________________________________ _____________________________________________________

2. What function does an "isolation switch" perform? ANS: _________________________________________________

3. Why must an oil-cooled machine be kept in an upright position? ANS: _________________________________________________

4. A welding machine should not be connected to the input (mains) until you have done what? ANS: _________________________________________________

5. What should you NOT DO to a machine that has a "forced draft fan"? ANS: _________________________________________________

6. What 2 things should you NOT DO on a DC machine or a Combination machine whilst that machine is operating? a) _______________________________________________ b) _______________________________________________


MOVE ON TO SECTION 3. READ THROUGH THE FOLLOWING NOTES.



BASIC WELDING TECHNIQUES In this section you will learn the basic procedures for performing fundamental SMAW welding processes upon "mild-steel". When you have completed this section you will be able to:

o Strike an arc and create "weld buttons" with AC output. o Lay stringer-beads upon flat plate. (Including stopping and restarting the arc). o Chip and clean welding beads and read a weld in order to establish corrective action.

1) STRIKING AN ARC

In this exercise you will be shown how to "strike an arc". This is the most fundamental of skills required for successful welding.

STRIKING AN ARC – TECHNIQUE

o Electrode holder is held in the hand in the manner one would hold a screwdriver.

o Stand in a comfortable position over the work in such a way that you can look directly down upon the weld position.

o Bring the electrode down toward the work (take aim) and then drop the hood (face shield).

o Scratch the tip of the electrode onto metal work surface in order to "strike" the arc.

o Immediately pull up (away from plate) and keep the arc going. Maintain a distance of the rod diameter between tip and work.

o Repeat the above steps and make button welds all over the surface of the plate.

WHAT TO DO WHEN

o The rod sticks to the metal -keep your hood (visor) down, release the electrode from the holder and put the holder on a hook (off the work). Keep your gloves on (wait a short while for cooling) and grasp the rod near the base. Bend the rod to break it away from the plate. Discard the rod, especially if the flux has been damaged (come off the wire).

o The arc just will not strike and the rod keeps sticking -check the following: The current setting may be too low -increase current (amps)

on fine setting. The work is not properly "grounded". Make sure that the

work, and the surface of the welding bench, is clean and RUST FREE. Rust is a poor conductor of electricity.


The flux is damaged or wet -try using a fresh electrode. (Check that rods are dry).

Your operating technique is too slow. Relax, and try to lift the rod off the work as soon as the spark occurs.

NOW VIEW THE VIDEO DEMONSTRATION ON "STRIKING AN ARC" AND THEN COMPLETE EXERCISE 1 ON THE NEXT PAGE.



EXERCISE 1 - STRIKING AN ARC

INSTRUCTIONS

o For purposes of practice this exercise involves the welding of "buttons" on a piece of 6 mm mild-steel plate.

o Your welding machine must be prepared in the manner described in the previous programme and the settings made for using 3.15 mm x 6013 electrodes on 6 mm MIS plate. (Welding current approximately 120 amps).

o Work on a steel welding bench. o Weld "buttons" onto a piece of 6 mm MIS plate as per diagram. Space the "buttons"

about 15 mm apart.

CHECK YOUR WORK BY COMPLETING THE CHECK-LIST FOR EXERCISE NO. 1.


CHECK LIST

PRACTICAL EXERCISE NO.1 - "STRIKING THE ARC" (Welding Buttons) o Check your completed exercise against the criteria in the list below. o Score a "Yes" (tick the block) if the work meets the criteria described. o Score a "No" if the work does not meet the criteria. o Repeat the exercise until you are able to score a YES to all criteria. o Have your Facilitator / Mentor check your work.

CRITERIA YES NO

1. Your metal work-piece has been cleaned up and is rust/scale free?

2. The work-lead ground connection is contacting "bright metal".

3. The current setting is at 120 amps (approximately).

4. You have selected the correct electrode.

5. You are, or were, wearing the necessary PPE? 6. You have managed to produce welding "buttons" over the full

face of the work-piece?

7. You are satisfied that you can strike an arc?

8. Have you asked your Mentor / Facilitator to check your work?


Answer the following questions:

QUESTION YES NO

1. List the possible reasons that could cause the electrode to "stick" to the work-piece when you attempt to strike the arc. i) _______________________________________________ ii) _______________________________________________ iii) _______________________________________________ iv) _______________________________________________

2. What should you do if the electrode sticks? (Tick the appropriate response) a) Pull the "ground clamp off the welding table". b) Shut down the machine. c) Quickly release the electrode from the holder.

MOVE ON TO “LAYING A STRINGER BEAD”.


2) LAYING A "STRINGER-BEAD" This exercise will offer you practice in the process of "laying a stringer bead". Maintaining a neat and "clean" bead is a skill that can only be acquired through much practice. A "stringer-bead' is simply a continuous run of filler-material deposited onto the plate. The rod is not moved from side to side during this operation. This exercise is made "across the body" for practice purposes. (However it may be made in any direction in application) STRINGER BEAD -TECHNIQUE

o Strike the arc in the "intended position". This is most commonly achieved by striking "inside the line" and then taking the rod back to the edge. The run begins from the edge and should be maintained at a uniform speed (rate of travel) along the line.

o The holder should be held in such a way that the tip of the electrode "trails the holder" by about 10 degrees. (Max.20). It is also acceptable for the rod to be kept "upright".

o The "speed" of travel should be such that the "ripple pattern" (behind the arc) is slightly "bullet shaped". Get used to keeping a watch on this as the weld progresses.

o The "width" of deposited material should be approximately 2, but not more than 3 times the diameter of the electrode (wire). The width of the bead is controlled (primarily) by: The distance between the rod tip and the work (the arc length). The size of the rod (wire diameter).

o During the process it may be necessary to stop the weld in order to change an electrode. Don't allow an electrode to burn down too far as this can damage the holder. As a rule do not allow the electrode to burn down to below 20 mm.

o Discard hot electrodes into a sand tray; don't just drop them on the ground where they will be "stood on" or cause a fire!

o When re-starting a weld do the following: Strike the arc about 20 mm ahead of the "crater" left where welding

stopped. Run the tip back (rapidly) until the rear of the "new crater" contacts

the rear of the "old crater". Move ahead (forward) as soon as the craters "overlap" and complete

the run. At the end of the run bring the electrode tip back over the bead and

lift it away from the metal.


NOW VIEW THE VIDEO DEMONSTRATION ON "LAYING A STRINGER BEAD" AND THEN COMPLETE EXERCISE 2 ON THE NEXT PAGE.




EXERCISE 2 - LAYING A STRINGER-BEAD INSTRUCTIONS

o For purposes of practice this exercise involves the welding of "stringer-beads" on a piece of 6mm mild-steel plate. Your welding machine must be prepared in the manner described in the previous programme and the settings made for using 3.15 mm x 6013 electrodes on 6mm MIS plate. (Approximately 120 amps)

o Work on a steel welding bench. o Weld beads onto a piece of 6 mm MIS plate as per diagram. Space the beads about

15 - 20 mm apart. N.B - The video offers you visual demonstration but it can't offer you the "feel" of handling the equipment!

CHECK YOUR WORK BY COMPLETING THE CHECK-LIST FOR EXERCISE NO. 2 ON THE NEXT PAGE.


CHECK LIST

FOR PRACTICAL EXERCISE NO. 2 - "LAYING OF STRINGER-BEADS"

o Check your completed exercise against the criteria in the list below. o Score a "Yes" (tick the block) if the work meets the criteria described. o Score a "No" if the work does not meet the criteria. o Repeat the exercise until you are able to score a YES to all criteria. o Have your Facilitator / Mentor check your work.

CRITERIA YES NO

1. The work-piece is clean and a good "earth connection" is / was established?

2. You were / are wearing the necessary PPE?

3. You successfully made at least 2 full beads along the work-piece?

4. The beads are straight, or on the lines. NOTE: Other Criteria will be explained in the next procedure.

MOVE ON TO "CHIPPING, CLEANING AND READING A WELD".


3) CHIP, CLEAN AND READ WELD BEADS In the following exercises you will learn how to chip off the slag from a weld bead and then, by "reading" the bead, decide what, if any, corrective action to take to improve the quality of your work. CHIPPING AND CLEANING THE BEAD In all SMAW processes you will have to remove the layer of protective "slag" from each bead after the weld has cooled or "frozen". Removal of the slag is important, especially when you have to "overlay" another bead upon an existing bead. Failure to "clean" the bead will result in the following welds being "weakened" from a condition called "inclusions". An inclusion is any section of weld that has "impurities" embedded in it. Inclusions result in "failure" of a weld, and this can lead to serious situations especially on a structure that is "load bearing". The basic procedure for "cleaning" a bead is as follows:

o The weld should be allowed to cool until the slag layer has "hardened". Never chip the slag whilst the metal is molten.

o Slag is removed by gently knocking it away with a "chipping hammer". If the weld has been laid "well" then slag will separate easily from the bead leaving a clean "shiny" surface.

o When chipping the slag one must wear eye protection. Usually the welder lifts the front "visor" of his mask, and looks through the clear "window".

o Care must be taken during chipping, as "hot particles" will fly off. These particles can fall onto the skin, hair or into the folds of your clothing and cause serious burns.

o Bystanders may also be struck by "flying slag". o If the bead has been poorly laid then it will contain "inclusions" or pockets

where the slag collects. This is very difficult to remove however much can be removed by "picking" with the pointed end of your chipping hammer.

o A wire brush is used to dislodge stubborn pieces of slag. READING A WELD There is only one "acceptable weld" and that is a good weld. All other welds are "unacceptable" and will often result in the failure of a joint. The ability to "read a weld" is something that every welder must be able to do. Typically we can determine, from reading the weld, whether one, or al/ of the following factors need adjusting:

1. The Amperage setting. 2. The Arc length. 3. Speed or "rate" of travel.

Study the diagram on the following page (below) and then compare your welds to those shown. Determine if your welding has reached "acceptable standards". If not,


return to exercise No.2 and repeat the process until you can consistently produce a "good weld" (stringer-bead). CROSS SECTION

A. A good weld. B. A weld resulting from amperage too low. C. A weld resulting from amperage too high. D. A weld resulting from arc-length too short. E. A weld resulting from arc-length too long. F. A weld resulting from travel speed too slow. G. A weld resulting from travel speed too fast.

It must be explained that a combination of faults may exist in a weld and that this is difficult to "read". As a general rule "beginners" tend to move too fast and hold an excessive arc length resulting in the result known (unkindly) as "bird droppings". You must also be aware that (some) corrective action be made during the process, such as changing the arc length and adjusting the travel speed. Once you are able to produce (consistently) a bead with:

o The desired "bullet shaped" ripples, and o A width of between 2 to 3 times the rod diameter,

then it can be said that you have gained sufficient "experience" to progress onto more advanced processes.


NOW VIEW THE VIDEO DEMONSTRATION ON" CLEANING AND READING A WELD" AND THEN COMPLETE EXERCISE 3 ON THE NEXT PAGE.





EXERCISE NO. 3 - CLEAN AND READ A WELD-BEAD INSTRUCTIONS

o Using your previous exercise (stringer beads), clean all the beads by chipping and brushing.

o "Read" the welding beads. o Enter you findings in the table / list below and suggest what "corrective action" you

need to make in order to improve the quality. o Have your Facilitator / Mentor check your work.

Bead No. On this bead I “read”… …and the action to correct this is?

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

THIS CONCLUDES PART 1 OF PROGRAMME 3 MOVE ONTO PROGRAMME 3 - PART 2.



WELDING TECHNIQUES (CONTINUED) We now enter the "real world of welding" where we shall begin to join metal plates together through an "arc-welding process". Metal sections can be joined using one or more of 5 basic "joint configurations" namely:

o Butt Joint. o Lap joint. o Corner joint. o "T" - joint. o and "edge joint".

In this programme you will learn how to make 3 common types of joint, namely:

o A" Square Butt -joint" on 6mm mild steel plate. o A "Single -V Butt -joint" on thick plate. o And a " T -joint" on 6mm plate.

4) SQUARE BUTT JOINT (6 mm m/s plate) ( Down-Hand) A "butt-joint" can be affected using various techniques depending on such things as:

o Metal thickness. o Accessibility to the joint. o Equipment available to the welder.

In this exercise we will concentrate on a square "butt joint". The metal plate that we shall use will be 6mm "mild-steel". This joint will require welding on both sides.


PROCEDURE 1. PREPARATION OF THE PLATES FOR WELDING

o Plates must be clean (rust free) and dry. o Edges to be welded must be flat and square. File or grind off any "flame-

cutting slag" if applicable.

2. SETTING THE PLATES o Place the 2 plates together onto your metal top welding-table. o Ensure that the welding table surface is clean and dry. o Ensure that both plates are horizontally aligned (flat). o Set the plates with their edges spaced 3.15 mm apart to form a "root gap".

Use the bare metal of a 3.15 mm rod to gauge this. o If desired, clamp the plates using suitable devices as applicable.

TACK WELD

o Set your machine to provide an output of approximately 100 - 120 Amps. o Using a 3.15 x 6013 electrode, tack one end of the join (make a 5 mm tack). o Recheck the root gap (using the wire of a 3.15 electrode) which may have

spread (opened) slightly. o Adjust the gap if necessary by squeezing the open ends together or by

tapping with a hammer. o Tack the opposite end and then tack the centre of the joint.

"ALIGNING THE JOINT" In the process of "tacking" the horizontal-alignment of the two plates may shift owing to "shrinkage" in the tacks. This problem will be most notable on small sections but can be corrected simply by turning the work over and "flattening" the plates, upon a flat surface, using a hammer to strike directly upon each tack-weld.


WELD THE JOINT (1STSIDE) o Run a stringer-bead along the full length of the joint in exactly the same

manner as you learnt in the second exercise. o At the end of the run, chip and clean the bead. o Read the weld and note any faults. o Turn the work over and inspect the reverse side. You should see a thin bead

of "penetration" protruding through the root gap. o Chip and clean this "penetration-bead" to remove any slag.

WELD THE JOINT (REVERSE SIDE)

o Run a stringer bead along the reverse side in exactly the same manner as the 1st side.

o Clean the weld after completing the run. o Read the weld.

NOW VIEW THE VIDEO DEMONSTRATION"MAKING A SQUARE BUTT-JOINT" AND THEN PERFORM EXERCISE 4, ON THE NEXT PAGE.




EXERCISE NO. 4 - "SQUARE BUTT JOINT WELD" INSTRUCTIONS

o Perform this exercise using 6mm M/S plate. o Cut plates to size (approximately 150 x 50 mm strips). o Set up the plates, on a suitable "platform", and create the correct "root-gap". o Tack the plates and check the "horizontal alignment". o Weld both sides. o Clean both beads and inspect your work. o Check your work against the criteria given in the check-list for practical exercise No.

4. o Have your Mentor / Facilitatorcheck your work.


CHECK LIST

FOR PRACTICAL EXERCISE NO. 4 -"SQUARE BUTT JOINT" o Check your completed exercise against the criteria in the list below. o Score a "Yes" (tick the block) if the work meets the criteria described. o Score a "No" if the work does not meet the criteria. o Repeat the exercise until you are able to score a YES to all criteria. o Have your Facilitator / Mentor check your work.

CRITERIA YES NO

1. The plates are clean and there is/was a good electrical contact to the work?

2. You are/were wearing all necessary PPE?

3. A 3,15mm root-gap was set between the plates.

4. The "horizontal alignment" is "flat" after "tack-welding".

5. First bead shows correct "penetration".

6. All slag removed from the bead and the root penetration.

7. Reverse side bead has been made and cleaned.

8. Beads are of consistent width @ approximately 6mm wide.

9. Your Mentor / Facilitator has checked your work.

MOVE ON TO "MAKING A SINGLE - V BUTT - JOINT".


5) BUTT - JOINT WITH SINGLE "V-GROOVE" (10 mm m/s plate) (Down -Hand) A Butt-Joint, made on metal plate over 6 mm, cannot simply be "square butted", some type of "edge-preparation" will be necessary in order to ensure full penetration. The preparation of the edge is a very important part of the joining process. The type of preparation will be determined (usually) by:

o Thickness of metal. o The welding "design" (For example: welded either sides or one side only).

For purposes of demonstration we will prepare 10 mm mild-steel plate with a "Single V-Groove" and weld from one side only. Having prepared the edges we will then proceed to weld the joint using 3 overlaying welding beads namely: 1strun - Called the "Root Run". 2ndrun - Called a "Hot pass". 3rdrun - Called the "Capping Layer". Let us look at the complete procedure in detail STEP 1 - METAL PREPARATION The edges to be welded must be "bevelled", by grinding or by flame-cutting, to produce a 600 angle as illustrated below. A "land" of approximately 2 mm must be left at the bottom edge to form the "root". The edges must be straight so that a parallel root gap is created when the edges are "aligned". STEP 2 - SETTING UP AND TACK-WELD It must be stressed that work must be carried out on a clean and flat metal surface.

o Lay the two plates on the flat surface and set the bevelled edges so that a "root-gap" exists between the "lands". Use a 3.15 mm wire (from a 3.15 electrode) to act as a gauge.

o Set your welding machine to approximately 150 amps output. o Using a 6013 electrode, tack one end in the "root". Make a strong tack-weld,

about 6 - 10 mm long.


o Re-check the root gap as it will most likely have "opened". "Adjust the gap" to return it to 3.15 mm. This can be done in several ways, the simplest being to "squeeze" the open end with your gloved hand.

o Tack the opposite end and then tack the centre of the joint. STEP 3 - "PRE-SET" THE WORK There is a "natural tendency" for a weld to "pull" as it cools. This will result in the warping of the plates (move out of "horizontal-alignment"). To counteract the warp we must "pre-set" the plates so that, upon welding, the "pull" will effectively bring them back into "horizontal-alignment". This is a simple procedure on a small work- piece.

o Turn the work-piece over onto the bench-top and place an edge upon a piece of scrap plate (about 6 mm thick).

o Strike the work-piece, using a suitable hammer, directly over the joint. Move along the joint, striking as you go. This action should create a slight "bow" (concave bend) to the back of the work-piece.

o Reset the work-piece onto the welding-bench surface with the welding side up, in preparation for welding the root-run.

STEP 4 - THE "ROOT WELD" The root weld is the "important weld" as this will determine the ultimate "strength" of the final product. Unfortunately the root weld is also the most difficult part of the welding process and requires a fair amount of skill to get right. The root weld must penetrate right through to the reverse side of the plates which means that all the elements of a "good weld" must be present, namely:

o Correct "amp setting". o Correct arc length. o Correct speed of travel. o The root gap must be "parallel" (this is why the edge preparation is very

important). At this time it is suggested that the work-piece is set up on a raised surface to avoid the weld from attaching the work to the bench. A typical jig, suitable for this purpose, is illustrated below.


Welding Jig: V cut - outs allow for proper penetration

The root run can now be performed, however, keep the following tips in mind as you go:

o Remove the slag from the tack-welds before you begin the root run. o Strike the arc inside the groove (at the inner end of the tack) and then quickly

run back to the start of the joint then continue in the "normal way". o Watch the weld pool ahead of the electrode tip. A small "keyhole" will form if

you are welding correctly. The "trick" is to maintain this "keyhole" as you move the electrode along at the correct speed and maintain the correct arc-length. If you move too fast the keyhole will disappear and, if you move too slowly a hole will blow through the gap. You will need much practice to get this technique right, but persevere because no-one gets this correct the "first time!".

o Attempt to keep the electrodes' tip in the middle of the groove (don't weave").

When you have completed the root-run, chip and clean all traces of slag from the bead. Inspect the reverse side of the work (use tongs to hold the work). You should see a thin line of filler material all along the joint indicating that full penetration has been achieved.


STEP 5 - THE "HOT PASS" This run, deposited directly upon the root-run, is made at slightly higher amperage and with the next size "up" electrode. In our case we shall make the hot-pass using a 4mm electrode and an output setting of approximately 160 Amp. In this run we are more concerned about "depositing filler" than penetration.

o Lay a stringer bead on top of the root run. o Chip and clean the bead upon completion.

This bead will finish slightly below the top edge of the plates. STEP 6 - "THE CAPPING LAYER" This run is deposited upon the Hot-pass layer and completes the weld. As this section is wider than normal we shall adopt a "weaving bead". The welding machine will be set to approximately 150 amps and again we shall use a 4 mm x 6013 electrode.

o Strike the arc inside the run and then move back to the end. "Weave" the electrode slowly from side to side in a "zig-zag" pattern.

o Do not run over the edges of the groove. Make a short but definite stop at the edge of the groove.

o Chip off the slag and inspect the weld.

NOW VIEW THE VIDEO DEMONSTRATION ON "MAKING A SINGLE-V BUTT-WELD" AND THEN COMPLETE EXERCISE 6, WHICH IS DETAILED ON THE NEXT PAGE.




EXERCISE 5 - SINGLE - V BUTT-JOINT INSTRUCTIONS

o Perform this exercise using 10 mm M/S plate. o Cut plates to size (approximately 150 x 75 mm strips). o Bevel the edges to 30 degrees. o Weld the plates together using 3 passes. o Check your work in 3 stages as outlined below.

Check No. 1 - Preparation and Root Run

CRITERION YES NO 1. Work-pieces have been cleaned and a good electrical connection

exists to the work-lead.

2. You are / were wearing the necessary PPE. 3. Plates have been prepared/bevelled to produce a 60⁰ included

angle.

4. A 3,15 mm root-gap was provided.

5. Work was given a "pre-set" after tack welds made. 6. Root-run made correctly, to produce a thin bead of "protrusion"

along the reverse side.

7. All slag has been removed from the root run.

8. Your Mentor / Facilitator has inspected the work to this stage.

PROCEED TO PERFORM THE “HOT PASS”.


Check No. 2 - Hot Pass

CRITERION YES NO

1. Correct electrode size (4 mm) selected.

2. Current setting changed for electrode (160 amps).

3. Bead has been run, cleaned and inspected for quality.

4. Your Mentor / Facilitator has inspected your work to this stage.

PROCEED TO PERFORM THE “CAPPING-RUN”.

Check No. 3 - Capping Run

CRITERION YES NO 1. Correct electrode size (3.15 mm selected. 2. Current setting adjusted to electrode selection. 3. Bead is welded, using small weaving process. 4. Bead is chipped and cleaned. 5. Bead shows consistent width and meets acceptable quality in appearance.

6. Mentor / Instructor has checked your work. Mentor / Facilitator sign: _______________________________________

MOVE ON TO "MAKING A T-JOINT".


6) "T-JOINT" ( 6 mm m/s plate) ( Horizontal / Vertical) A "T-joint" is essentially made using a "fillet-weld" technique. In the exercise we shall be using a slightly different welding position, namely a "horizontal / vertical" position. Owing to the metal thickness, 6 mm M/S plate, we will require only one pass along the joint with a 3,15 or a 4 mm electrode. The criteria being that the weld face width must be at least 6 mm, which is the material thickness. PREPARATION For this exercise it is essential that the bottom plate is flat and that the upright section has a straight and square edge. 80th plates should be clean and rust free and set up on your steel topped welding-bench. The upright section is placed onto the bottom plate and supported in such a way that it will remain upright for purposes of tacking. There is no "rule" as to how you support the upright-section and the method used in the demonstration is just one convenient way to do it. When you have aligned the plates into position then the next step is to tack them together. Arrange your work so that you will be welding more or less "across your body" from left to right. TACK WELD The first tack is made at any "corner position". The following tips will assist you:

o Set the welding current to 120 amps (for 3,15 mm wire) or to 160 amps (for 4 mm wire).

o Hold the electrode at an angle of 45 degrees from the base (table) and with a backward lean (trail angle) of 45 degrees.

o Strike the arc just inside the corner and run back quickly to the end. Allow a good penetration of filler into the tack. Run a short bead, approximately 5 to 10 mm long.

o After the first tack check the joint angle using a "square". o If necessary, set the angle to square, by tapping the work with a hammer. o Next, repeat the tacking process in the "diagonally opposite corner". o Tack the two remaining corners. o Chip and clean all tacks prior to running a full weld.

WELD ALONG JOINTS Technically we are about to perform a weld in the "horizontal/vertical, (or "HN" position") and make a "fillet weld". Although on a small work-piece, you could tilt


the work so that you are welding "flat" (Down-hand), we shall, for experience, work in the "vertical-horizontal position". There is nothing difficult in this practice provided that we observe one or two things namely:

o Use the largest wire size possible, as this will offer better "slag control" and permit a faster rate of travel.

o Use a slight "weaving action" of the electrode. This action will tend to sweep the molten pool "up against the vertical plate". Try to think of this .action as "sweeping" the pool uphill. The reason for this is to ensure equal penetration of the weld into both plates.

o Maintain the electrode angle at 45/45 degrees (Lean and Trail) aiming the tip directly into the "root".

o Maintain a steady arc-length (wire thickness) and move at a steady rate of travel.

NOW VIEW THE VIDEO DEMONSTRATION ON "MAKING AT-JOINT" AND THEN PERFORM EXERCISE 6.



EXERCISE 6 - "T-JOINT / FILET WELD"

INSTRUCTIONS

o Perform this exercise using 6mm M/S plate. o Cut plates to size (approximately 150 x 50 mm strips). o Set up the plates to form a "T-Joint", with suitable supports, on your welding bench. o Weld the joint using 3.15 or 4 mm electrodes. o Check your work against the "criteria" given in the check-list for practical exercise

No. 6.


CHECK-LIST FOR PRACTICAL EXERCISE NO. 6

o Check your completed exercise against the criteria in the listing below. o Score a "YES" response (tick the block) if the work meets the criteria described. o Score a "NO" response if the work does not meet the criteria described. o Repeat the exercise, if necessary, until you are able to score a "YES" response to all

the criteria. o Have your Facilitator / Mentor check your work and sign off this exercise when

completed.

CRITERIA YES NO

1. Work-pieces are clean and edges are straight / square.

2. Welding-current set to correct setting for electrode used.

3. Upright leg is set to 90⁰ after tacking.

4. Weld faces (both) are of uniform width (6 - 8 mm wide).

5. Both welding beads meet "acceptable standard".

6. Your Mentor / instructor has checked your work?

Facilitator / Mentor signature: ____________________________ Date: _________________

THIS CONCLUDES THE SMAW SERIES.

SHIELDED METAL ARC WELDING..."Shielded Metal -Arc Welding" or "SMAW". The process is performed...

Documents

Transcript of SHIELDED METAL ARC WELDING..."Shielded Metal -Arc Welding" or "SMAW". The process is performed...