Presentation on theme: "Using Gas Welding Equipment"— Presentation transcript:
1 Using Gas Welding Equipment Ag IAg MechanicsUnit 2
2 Competencies to be Developed Identify major parts of propane and oxyacetylene welding equipmentChange oxygen and acetylene cylindersTurn on and adjust oxyacetylene controlsLight and adjust oxyacetylene torchesShut off and bleed oxyacetylene equipmentCheck for leaks in gas equipment
3 IntroductionMany gases will burn, making them both dangerous and beneficialBurning gases are used in ag mechanics to do many thingsHeat, cut, weldWeld: to join by fusionFusion: melting together
4 Introduction Gas: any fluid substance that can expand without limit. This expandable nature also means that a gas can be compressedCompress: apply pressure to reduce in volume
5 Compressed GasDangerous because it is under pressure and trying to get freeIf the gas is flammable there is the additional danger that it may explode or burn out of controlFortunately, we have suitable equipment and techniques available to use compressed, combustible gasses safely
6 Acetylene and PropaneMost popular for heating, cutting and welding metalsThey must be mixed with oxygen from the air or pure oxygen from tanks before they will burn.Refer to unit 1 for Reducing Hazards in Agricultural Mechanics
7 General Precautions with Compressed Gases Wear safety glasses at all timesStore fuel gas cylinders separately from oxygen cylindersKeep gas cylinders upright and chainedDo not bump or put pressure on pipes, connections, valves, gauges or other equipment connected to compressed gas cylindersWhen connections are opened or cylinders are changed check for leaks before using equipmentNever use grease or oil on equipment—spontaneous or instant fires may resultFollow procedures for turning systems on and offWork only in areas that are free of materials that burn
8 General Precautions with Compressed Gases Screw caps on all cylinders that do not have regulatorsKeep equipment or cylinders that may discharge gas pointed away from the operator and other peopleNever leave clothing were it can become saturated by oxygen and fuel gasesLearn to recognize the odors of combustible fuelsProtect gas cylinder storage areas with locked link fences or concrete enclosures.If gas equipment catches fire, immediately turn off the gas at the tanks. If this is not practical or this action does not extinguish the gas fires, evacuate the area and call for help.
9 Gas Burning EquipmentShops have either a manifold or portable rig set-upManifold: pipe with two or more outletsRig: self contained piece of apparatus assembled to conduct an operationOxyacetylene: a shortened version of the words oxygen and acetyleneIt refers to equipment and processes where the two gases are used togetherShops may also use propane and oxygen torches and propane furnaces
10 Oxyacetylene Equipment Major partsCartCylindersValvesRegulatorsGaugesHosesTorch assemblies
11 TorchMixes gases and discharges them to support a controllable flame
12 CylinderLong, round tank with extremely thick walls built to hold gases under great pressure
14 GaugeMeasures and indicates the pressure in the hose, tank or manifold
15 Hoses Flexible lines that carry the gases Made of rubber reinforced with nylon or there material to withstand high pressure and heavy useRed= acetyleneGreen= oxygen
16 The Rig Acetylene Side Oxygen side Acetylene cylinder Cylinder valve Red or brownCylinder valveRed cylinder pressure gaugeRegulatorHose pressure gaugeRed hoseAcetylene valve on torchOxygen sideOxygen cylinderGreen cylinder pressure gaugeRegulatorHose pressure gaugeGreen hoseOxygen valve on torchTorch mixing chamberTorch tip
17 Setting Up Acetylene Oxygen cylinders Left hand threadsColor coded red (brown in our shop)Oxygen cylindersRight hand threadsColor coded greenBefore attaching regulators to cylinders, crack the cylinder by turning the gas on and off quickly to blow out any dustWhen attaching regulators, hoses, gauges or torch connections, the connectors must be threaded in the correct direction. The red color coding and opposite threads for acetylene are means of preventing the accidental mixing of acetylene and oxygen except in the torch its self.
18 Setting Up All connections are gas tight when screwed on properly Caution!! Oxygen and acetylene valves on torches seal with light finger pressure. Over tightening will damage the seats of the valves. A seat is the point where the movable part of the valve seat seals off the gas.
19 Turning On the Acetylene and Oxygen Use the following sequence to turn on the gases.DO NOT STAND IN FRONT OF GAUGES WHILE THE GAS IS BEING TURNED ON!!!Step 1: Close the acetylene valve on the torchStep 2: Close the oxygen valve on the torchStep 3: Turn the acetylene regulator handle counter clockwise until no spring tension is feltStep 4: Turn the oxygen regulator handle counter clockwise until no spring tension is felt.
20 Turning on Oxygen and Acetylene Step 5: Open the oxygen cylinder valve slowly until the pressure gauge responds. Open the valve all the way.Step 6: Open the acetylene cylinder valve slowly half a turnNEVER open the acetylene cylinder more than half a turn. This is so it can be shut off quickly in the case of emergency.Step 7: Open the oxygen torch valve an 1/8 of a turn. Turn the oxygen regulator handle clockwise until the pressure gauge reads 10 psiStep 8: Open the acetylene torch valve an 1/8 of a turn. Turn the acetylene regulator handle clockwise until the pressure gauge reads 5 psi. Close the acetylene valve.
21 Turning on Oxygen and Acetylene Step 7 & 8 purge the lines and set regulators to a safe starting pressurePurge the lines: remove undesirable gasesThis makes the unit pressurized and ready to go.
22 Testing for LeaksLeak test should be performed when first setting a rig up, when cylinders are changed or if the odor of acetylene is present when the rig is not in useLeaks should be tested for using a small amount of water and nondetergent hand soapThe solution should be rubbed around fittings and any other places that a leak may exist using a 1” paint brushIf a leak exist it will cause the soap solution to bubble
23 Lighting and Adjusting Torches Two types- welding and cuttingTo lightOpen the acetylene valve an eighth of a turnUse a spark lighter to ignite the torchNEVER use matches or a lighter!DO NOT point the torch directly into the lighterDO NOT point the torch towards other peopleOpen the acetylene valve slowly until the flame is ¼” off the tip of the torch, increase or decrease the flow until the flame just touches the tipThis flame is called a carbonizing flame.Carbonizing flame is one with excess acetylene.
24 Lighting and Adjusting Torches Turn the oxygen valve on slowly and watch the inner flame shorten. Continue to add oxygen until the long, inner flame just fits the cone.This is a neutral flameNeutral flame: one with the correct balance of acetylene and oxygen.This flame is correct for heating, cutting, and welding
25 Lighting and Adjusting Torches If additional oxygen is added, the cone becomes sharp and the flame noisy. This is an oxidizing flame or one with an excess of oxygen.It is hottest type of flame but not recommend for anything but special types of applications
27 Shutting Off TorchesTorches become a fire hazard if the procedure is not followed when shutting them off.Use gentle pressure on torch valves to keep from damaging their soft internal parts.First close the acetylene valveClose the oxygen valve last
28 Bleeding Lines Removing all gas from the lines and equipment Procedure Turn off the acetylene at the cylinderTurn off the oxygen at the cylinderOpen the acetylene valve at the torch until both regulators return to zero. Close the acetylene valve at the torchOpen the oxygen valve at the torch until both regulators return to zero. Close the oxygen valve at the torchTurn all regulator handles counterclockwise until they are easy to turnCoil the hoses over the cart handlesStore the rig in a suitable place.
29 REVIEW POP QUIZ 1. What color are acetylene hoses? 2. What color are oxygen hoses?3. Acetylene should be at what pressure to light the torch?4. What is used to check for gas leaks?5. What material is used to reinforce gas hoses?6. What two gases are used in the agricultural mechanics shop?7. What is used to compress gases?8. How far should the acetylene tank valve be opened?9. Why are compressed gases dangerous?10. Define the term rig.