2WarningsWelding can be safe when proper measures are taken to protect yourself and others from potential hazards.Understand and follow all warning labels found on equipment and with all consumables.
3Potential HazardsProtect yourself and others from potential hazards including:Fumes and GasesElectric ShockArc RaysFire and Explosion HazardsNoiseHot objectsWelding Sparks
4Fumes and GasesWelding fumes can be harmful to the welder causing implications such as:Irritation of the respiratory tractMetal fume feverSlightly increase the risk of lung cancerUse enough ventilation, exhaust at the arc, or both, to keep fumes and gases from your breathing zone and the general areaUse a respirator if needed or required by the process.The ventilation system must be on while welding at all times.
5Electrical Shock Electric shock can kill Do not touch live electrical partsPrimary Voltage – , volt input powerSecondary Voltage – 6 to 100 volts for weldingInsulate yourself from work and groundFollow all warnings on welding equipmentWear insulated clothingAlways shut off machinery when done and roll the cords up neatlyDo not make repairs yourself, alert your instructor immediately!
6U.V. RaysWelding will produce ultraviolet rays that are harmful to the human eye and skin. Proper protection is needed to avoid bodily harm.Arc rays are ten times brighter than the sun and can injure eyes and burn skinPrecaution must be taken to protect your eyes and skin from UV radiation. The welding arc is brighter than the sunWear correct eye and body protection10 shade helmetSafety Glasses under the helmetGlovesArm and Body ProtectionJacketShoulder CoversCoveralls
7Fire Hazards and Material Safety Welding sparks can cause fires and explosionsSparks and spatter from the welding arc can spray up to 35 feet from your workFlammable materials should be removed from the welding area or shielded from sparks and spatterAlways clean painted materialsAll welding booths should be cleaned thoroughlyHave a fire extinguisher readyInspect area for fires 30 minutes after weldingWatch for sharp metal edgesCool all welded metal in the water tank.
8Ear Protection Loud noises can damage your hearing Keep loud noises at a safe level by using proper hearing protection such as:Ear plugsEar muffs
9Protective Clothing Welders must wear protective clothing for Protection from sparks, spatter and UV radiationInsulation from electric shockProtective clothing includes …Fire-proof clothing without rolled sleeves, cuffs or fraysWork bootsWelding gloves, shirts jackets, bibs, and fire-proof pantsWelding cap, helmet and safety glassesEar protection – ear plugs and muffsMost importantly safety glasses are to be worn at all times in the shop
10Improper Protective Clothing List and describewhat is wrongin this picture
11Basic Electricity and Welding Arc WeldingBasic Safety
12Arc Welding Circuit and Concept The electricity flows from the power source, through the electrode and across the arc, through the base material to the work lead and back to the power source.Identify all the above parts for the arc welder, describe the function of each part, and determine each of the parts safety aspects.
13Electrical ConceptsDC -DC +Voltage – The electrical potential or pressure that causes current to flowMeasured in VoltsCurrent – The movement of charged particles in a specific directionMeasured in AmpsPolarityDC- (Direct Current Electrode Negative)DC+ (Direct Current Electrode Positive)AC (Alternating Current)ALWAYS REMEMBER THAT VOLTAGE WILL HURT BUT AMPERAGE CAN BE FATALAC
14Electrical Lead Condition Before starting an operation, always check the condition of all electrical leads.Cracked and worn leads can lead to fatal shock.All electrode holders or “stingers” should be in tack and not cracked or missing pieces.All plugs and outlets should be in tack. Never set-up a welder with a broken plug or into a broken outlet.Never operate a welder with splices showing in the leads.
17SMAW Key PartsElectrode Holder: Also known as the “stinger” Handle-like tool that holds the electrode while welding.Never hold this part with your bare hand while welding.Ground Connection: Also known as the “workpiece connection clamp” that connects to the work to complete the electrical circuitPower Source: Where the welder plugs intoAmperage Scale: Determines the amount of “heat” or power the welder will operate at.Polarity Switch: Setting that determines how the electrons will flow during the welding process.On / Off Switch: Turns the welder on / off. Make sure the switch function properly at all times.
18SMAW PrinciplesThe American Welding Society defines SMAW as Shielded Metal Arc WeldingSMAW:Is commonly known as ‘Stick’ welding or manual arc weldingIs the most widely used arc welding process in the worldCan be used to weld most common metals and alloys
19SMAW Welding CircuitCurrent flows through the electrode cable, to the electrode holder, through the electrode, and across the arcOn the work side of the arc, the current flows through the base material to the work clamp and back to the welding machine
20SMAW ProcessIdentify all the above segments for the SMAW process, describe the function of each segment, and determine if any safety aspects exist.
21The Electrode What is it? Is a consumable - it gets melted during the welding processIs composed of two partsCore Rod (Metal Filler)Carries welding currentBecomes part of the weldFlux CoatingProduces a shielding gasCan provide additional fillerForms a slag
22Electrode Classification Electrodes are classified by a numbering systemE6013E = Electrode60 or first two numbers = Tensile strength (thousands of pounds1 or third number = Welding position3 or fourth number = Welding current type and depth of weld penetration.Pictured above are E-7018 electrodes. Identify what the tensile strength is for this electrode.
23Electrode Classification Third Digit E_ _ 1 _ = Usable in all directionsE_ _ 2 _ = Usable in flat and horizontal positions onlyE_ _ 4 _ = Usable for vertical down onlyPictured above are E-6011 electrodes. Identify what each digit resembles up to the third digit.
24Electrode Classification Fourth Digit E_ _ _ 0 = DC reverse polarity onlyE_ _ _ 1 = AC and DC reverse polarityE_ _ _ 2 = AC and DC straight polarityE_ _ _ 3 = AC and DCE_ _ _ 4 = AC and DCE_ _ _ 5 = DC reverse polarityE_ _ _ 6 = AC and DC reverse polarityE_ _ _ 8 = AC and DC reverse polarityPictured above are E-6013 electrodes. Identify what each digit resembles.
25The ArcAn arc occurs when the electrode comes in contact with the work-piece and completes the circuit … like turning on a light!The electric arc is established in the space between the end of the electrode and the workThe arc reaches temperatures of 10,000°F which melts the electrode and base materialDon’t look at the arc without proper eye protection.Wear proper body protection. The UV rays will cause bodily harm.Arc burning off the electrode
27Weld PuddleAs the core rod, flux coating, and work pieces heat up and melt, they form a pool of molten material called a weld puddleThe weld puddle is what a welder watches and manipulates while weldingDon’t touch the hot puddle!!! The metal is hot!!!
28Shielding Gas A shielding gas is formed when the flux coating melts. 23Shielding Gas4A shielding gas is formed when the flux coating melts.This protects the weld puddle from the atmosphere preventing contamination during the molten stateDon’t touch the metal!!! The metal is hot!!!Shielding gas can cause bodily harm. Be sure proper ventilation is being used.The shielding gas protects the molten puddle from the atmosphere while stabilizing the arc
29Solidified WeldmentAs the molten weld puddle solidifies, it forms a joint or connection between two pieces of base materialWhen done properly on steel, it results in a weld stronger than the surrounding base metalDon’t touch the metal!!! The metal is hot!!!
30SlagSlag is a combination of the flux coating and impurities from the base metal that float to the surface of the weld.Slag quickly solidifies to form a solid coating which slows the cooling rate of the weldThe slag can be chipped away and cleaned with a wire brush when hardDon’t touch the metal!!! The metal is hot!!!Slag can be dangerous when being removed. Wear the proper safety protection.This welder chips the slag off of a weld during the repair of railroad tracks
32GMAW DefinedAn arc welding process that uses an arc between a continuous filler metal electrode and the weld pool.The process uses a shielding gas that protects the weld from contamination.Without using a shielding gas the weld becomes pitted and contains no strength value.
33Pitted GMAW WeldmentWeld is Pitted from improper flow of shielding gas
34GMAW Safety Points Fumes and Gases can be dangerous Keep your head out of the fumesUse enough ventilation, exhaust at the arc, or both, to keep fumes and gases from your breathing zone and the general areaLocal exhaust and mechanical ventilation can be used without reducing weld qualityElectric Shock can kill – to receive a shock your body must touch the electrode and work or ground at the same timeDo not touch the electrode or metal parts of the electrode holder with skin or wet clothingKeep dry insulation between your body and the metal being welded or groundThe coil of wire is ‘electrically hot’ when the trigger is pulled
35GMAW Safety Points (Continued) REMEMBER – Gas Cylinders require SPECIAL safety precautionsCylinders must be secured in an upright positionCylinders should be located in an area away from arc welding, cutting, heat, sparks, and flameShut off the gas cylinder when finished.NCWHS uses a 75% carbon dioxide and a 25% argon mix for shielding gas.Don’t bleed or purge the lines after an operation. This gas will not combust / burn.
36GMAW ProcessDuring the GMAW process, a solid metal wire is fed through a welding gun and becomes the filler materialInstead of a flux, a shielding gas is used to protect the molten puddle from the atmosphere which results in a weld without slag
37GMAW Process (Continued) Three things happen when the GMAW gun trigger is pulled:The wire electrode begins to feedThe circuit becomes electrically ‘hot’Shielding gas flows through the gun and out the nozzleCurrent flows from the power source through the gun cable, gun, contact tip to the wire and across the arc.On the other side of the arc, current flows through the base metal to the work cable and back to the power source
39GMAW Key PartsGun Housing: Holds or houses the welding wire liner, gas line, and trigger in one pieceConductor Tube: The angled part of the gun that the wire and shielding gas flow through during the weld operationGas Diffuser: Disperses the shielding gas onto the weldmentContact Tip: The part where the welding wire runs through. Different sized tips accommodate different sized wire.Nozzle: The cover for the end of the gun that keeps spatter from sticking to the contact tip and gas diffuser and plugging the gun up.
40GMAW ProcessWelding Tip: Generally, drag on thin sheet metal and push on thicker materialsShielding GasSolidified Weld MetalArcElectrodePuddle
41GMAW Electrode A GMAW electrode is: A metal wire Fed through the gun by the wire feederMeasured by its diameterGMAW electrodes are commonly packaged on spools, reels and coils ranging from 1lb to 1000lbs
42GMAW ArcAn electric arc occurs in the gas filled space between the electrode wire and the work pieceElectric arcs can generate temperatures up to 10,000°F
43GMAW Weld PuddleAs the wire electrode and work piece heat up and melt, they form a pool of molten material called a weld puddleThis is what the welder watches and manipulates while welding
44Shielding GasGMAW welding requires a shielding gas to protect the weld puddleShielding gas is usually CO2, argon, or a mixture of both
45Final WeldThe welder “lays a bead” of molten metal that quickly solidifies into a weldThe resulting weld is slag free
46Weld Examples GOAL - Make Good Welds Eliminate Porosity Eliminate Ropey Convex beadEliminate Excessive Spatter
48Terms and DefinitionsBackfire: A short pop of the torch flame followed by extinguishing of the flame or continued burning of the gases.Flashback: when the torch flame moves into or beyond the mixing chamber.Preheating: Heating prior to a welding or cutting operation
49Equipment Required Oxygen cylinder Acetylene cylinder Pressure regulatorsTwo hoses encased togetherWelding torch with tipsWelding goggles and safety glassesStrikerCheck valves to prevent flashback
58Safety Rules for Oxy-Acetylene Workplace Keep the work area free of grease, oil, and flammable materialsCool or quench hot metal and extinguish all sparks before leaving. Sparks can travel up to 35 feet.Don’t leave torches, or hot metal where someone will pick them upNever carry matches or lighters into any work area
62Oxygen/ Acetylene Cutting Torch Stored on Unsafe Cart
63Oxygen/ Acetylene Cutting Torch Stored in Flammable Liquids Cabinet
64Regulator PartsPressure regulators reduce the supply pressure, indicated by the high pressure gauge to suitable working pressure, indicated by the low pressure gauge. By turning the adjusting screw, proper working pressures can be achieved.
65Personal Safety Shirts Pants or Coveralls Shoes Gloves Safety Glasses keep collar and sleeves buttoned to keep out sparks. Avoid wearing shirts with pockets.Pants or Coverallsno cuffs and come over shoe topsShoesleather, cover entire footGlovesLeather, never use to pick up metalSafety Glassesworn under helmets and goggles and all times.
66Eye Protection Wear safety glasses at all times Wear welding goggles or a face shield with a lens no. 4-6 while using torch equipmentwhen in doubt start with too dark of a lens and then switch to a lighter one.
68Pressure Regulating Valves Each regulator has two gauges mounted on a single manifold. One indicates cylinder pressure and the other indicates working pressure for the torch.Each regulator has an adjusting screw or T-screw, so pressure to the torch can be quickly controlled by turning the screw righty-tighty to increases pressure and left-loosey to decrease pressure.
69Regulator AttachmentAcetylene connectors have a V-groove left handed threadOxygen connectors have a plain surface right handed thread
70PSI Settings Acetylene = 15 psi. max Oxygen = 40 psi. max Over 15 psi. can be fatalOur regulators in the NCWHS lab will be set at 10 psi. max.Oxygen = 40 psi. maxOver 40 psi. will dilute the heat of the flameOur regulators in the NCWHS lab will be set at 30 psi. max.
71Torch PartsTorch body is the part of the torch that is held like a pencil. It contains two needle valves to control the flow of gasThe welding head contains a mixer, mixing throat, and the welding tip
72Types of Flames Oxidizing Neutral Excess oxygen with no feather, makes hissing sound. Sounds like an angry snake.Least used for anythingNeutralBurns equal amounts of oxygen and acetylene and has a clear edged inner coneMost used
73Types of Flames Carburizing Excess acetylene with an acetylene feather two to three times the length of the inner coneWhile burning it will produce a heavy black smoke flameUsed some in hardsurfacing, adds carbon to metal
74Operation Safety1. Before you start make sure personal safety is followed.2. Make sure you have had instruction3. Release adjusting screw on regulators before opening valves4. Stand on the opposite side of the regulator when opening a valve5. Open cylinder valve slowly, oxygen first all the way open acetylene just a quarter of a turn
75Operation Safety (II)6. Do not use or compress acetylene at pressures higher than 15 psi.7. Set working pressures as desired.Acetylene: 10 psi for NCWHS labOxygen: 30 psi for NCWHS lab8. Light acetylene first 9. Never use oil on regulators or any equipmentIf oil mixes or touches the acetylene it will combust10. Do not use compressed air as a substitute for oxygen11. Keep heat, flames, and sparks away from combustibles.12. Keep hoses out of sparks or spatter to prevent leaks
76Safety Lighting the Torch Check the torch valves to make sure they are closedOpen the oxygen tank valve full openOpen the acetylene tank valve ¼ turnTurn on the oxygen knob on the torch bodyThis is located next to the acetylene knobTurn the acetylene gas on no more than ¼ turnStrike and lightMix oxygen into the flame with the mixing knob on the torch body. While mixing you want to create a neutral flame. Press down on the cutting lever also to make sure the flame does not jump.The mixing knob is located half-way up the torch body next to the cutting lever
77Shutting down the unitShut down the flame by turning off the acetylene knob on the torch body.Close the oxygen mixing knob located half-way up the torch bodyShut off the tanks by closing the tank valvesOpen the acetylene to purge or bleed the lineWhen both gauges read zero, close the valveOpen the oxygen valveRelease pressure on the regulators by turning adjusting screw left or T-screw (out). DO NOT remove the T-screwCoil hoses and put tools away