- - AGRICULTURE CORE CURRICULUM - - (CLF2000) Advanced Core Cluster: AGRICULTURAL MECHANICS (CLF2250) Unit Title: oxyacetylene WELDING ___________________________________________________________________________ (CLF2252) Topic: Oxyacetylene WELDING Time Year(s) EQUIPMENT SETUP & ADJUSTMENT 4 Hours 1 / 2 / 3 / 4 ___________________________________________________________________________ Topic Objectives: Upon completion of this lesson, the students will be able to: Learning Outcome #: (F-3) - Set up, use, shut off, and store an oxyacetylene welder properly. Special Material and Equipment: Oxygen and acetylene cylinders, regulators and hoses, torch, tips, open-end wrench, striker, protective clothing, gloves, and goggles References: Cooper, Elmer L. (1987). AGRICULTURAL MECHANICS: FUNDAMENTALS AND APPLICATIONS. Albany, NY: Delmar Publishers. Phipps, Lloyd J., & Reynolds, Carl L. (1990). MECHANICS IN AGRICULTURE (4th ed.). Danville, IL: Interstate Publishers. Resources: Deere & Company. (1987). WELDING (6th ed.) (Fundamentals of Service (FOS) Series). Available from: John Deere Technical Services, Dept. F, John Deere Road, Moline, IL 61265 (Available in Spanish) Evaluation: Quiz by instructor TOPIC PRESENTATION: Oxyacetylene Welding Equipment Set-up & Adjustment A. Oxyacetylene Equipment Setup 1. Cylinders a. Place the oxygen and acetylene cylinders side by side in a vertical position and secure them from falling. b. Remove the cylinder valve protection caps and store them for reuse later when the cylinders are empty. c. Check the cylinder valve threads to verify that they are in good condition and free of dirt and oil. d. Briefly "crack" the cylinder valves (slightly open) to blow out any dust or dirt that may be lodged there, so it does not enter the regulators. 2. Regulators a. Verify that the regulator inlet connection is free of dirt, oil, grease, or any other obstruction. b. Connect the oxygen and acetylene regulators to the proper cylinder valves using an open-end wrench, being careful to tighten the connection nut firmly without excessive force. c. Turn the regulator adjusting screw out (counterclockwise) on each regulator until it is loose. d. Stand to one side of the oxygen regulator gauge and open the oxygen cylinder valve slowly so the high-pressure regulator gauge needle gradually moves up to approximately 2000 psi if the cylinder is full, then open the valve completely. e. Slowly open the acetylene cylinder valve only one half turn, so it can be turned off quickly in an emergency. Acetylene cylinders read about 350 psi when full. 3. Hoses and Torch a. Connect the oxygen hose (green) to the oxygen regulator outlet and the acetylene hose (red) to the acetylene regulator outlet. 1) The oxygen hose has right-handed thread connections. 2) The acetylene hose has left-handed thread connections. b. Blow out the hoses with cylinder gas to remove dust, dirt, and talcum powder (used to protect new hoses in storage), which may plug the small gas passages in the torch. 1) Turn the adjusting screw on the regulators clockwise until 5 psi shows on the low (working) pressure gauge. 2) Allow the cylinder gas to escape until the inside of the hoses are clean. c. Connect the free end of the oxygen hose to the torch connection marked "OXY" and the free end of the acetylene hose to the torch connection marked "FUEL." d. Select the tip or nozzle size appropriate for the metal thickness (see welding tip selection chart), and only hand-tighten the tip to the torch. e. Test for leaks by pressuring the system (described in paragraph B-1 below) and then brushing a non-detergent, soapy water on all the connections. 1) Soap bubbles will indicate a leak; also listen for the hiss of escaping oxygen and try to discern the smell of acetylene. 2) If a leak is found in a connection, retighten it or replace the faulty connection. 3) Leaking cylinders should be returned to the supplier. B. Adjusting the Torch 1. Pressurizing the System a. Close both control valves on the torch handle clockwise, finger tight only. b. Verify that the regulator screws are turned out and loose. c. Standing to one side of the regulator, slowly open the oxygen cylinder valve until the pressure gauge responds, then open the valve all the way. d. Slowly open the acetylene cylinder valve 1/2 turn or one turn of the wrist. e. Open the torch oxygen valve 1/8 turn and then screw in the oxygen regulator valve until the desired working pressure is indicated on the regulator working pressure gauge. Close the torch oxygen valve. f. Open the torch acetylene valve 1/8 turn and then screw in the acetylene regulator valve until the desired working pressure is indicated on the regulator working pressure gauge. Close the torch acetylene valve. 2. Lighting and Adjusting the Torch a. Be sure all protective clothing and goggles (No. 5 shaded lens) are on before proceeding to light the torch. b. Hold the torch in one hand and the striker (spark lighter) in the other. c. Open the torch acetylene valve no more than 1/4 turn and ignite the gas with the striker. d. Open the torch acetylene valve until the flame is no longer smoking. e. To set a carburizing flame (excess amount of acetylene): 1) Open the torch oxygen valve until a feathered cone exists in the flame. 2) Three flame zones are present. They are the inner cone, the acetylene feather, and the outer envelope. e. To set a neutral flame (equal amounts of oxygen and acetylene): 1) Open the torch oxygen valve until the acetylene feather disappears and only the inner cone and outer envelope exist. 2) When the feathery edges of the inner cone disappear, a neutral flame is present. f. To set an oxidizing flame (excess amount of oxygen): 1) Open the torch oxygen valve beyond a neutral flame to a point where the flame is pale blue. 2) The inner cone will be shorter, will become slightly pointed, and the flame will be more noisy than the neutral flame. C. Oxyacetylene Equipment Shut-down and Storage 1. Torch Shut-down: a. First, turn off the torch acetylene valve. If a small flame remains on the tip, the acetylene valve is leaking. b. Turn off the torch oxygen valve last. 2. Depressurize the system: a. Close both cylinder valves. b. Open the torch acetylene valve to depressurize the acetylene gauges and hose. c. Close the torch acetylene valve. d. Open the torch oxygen valve to depressurize the oxygen gauges and hose. e. Close the torch oxygen valve. f. Turn out the adjusting screws on the oxygen and acetylene regulator valves. 3. Storage of Cylinders a. Store cylinders in a well-ventilated, fireproof room or cage with flameproof electrical fittings. b. Do not store oxygen and combustible gases such as acetylene together. c. Store acetylene cylinders in an upright position--liquid acetone from within the cylinder can leak into valves. d. Write "empty" with chalk or soapstone on empty cylinders and keep them separate from full cylinders. e. Store cylinders away from sources of heat, since heat increases the pressure of gas and may weaken the cylinders. f. Store cylinders away from oil and grease, since these combustibles may ignite spontaneously when in contact with pure oxygen. g. Keep the cylinder caps on cylinders while in storage to prevent cylinder valve damage, which could result in an oxygen cylinder taking off like a missile. _________________________________________________________ ACTIVITY: 1. Set up oxyacetylene equipment. 2. Select a tip size using a tip chart. 3. Pressurize the system and light a torch. 4. Adjust for carburizing, neutral, and oxidizing flames. 5. Dismantle the oxyacetylene equipment and put the cylinders in storage. _________________________________________________________ 7/1/91 OLR/tf #%&C