1. WELDING EQUIPMENT WELDING EQUIPMENT BRAZING GAS FUSION WELDING GAS FUSION WELDING ELECTRIC ARC WELDING ELECTRIC ARC WELDING INDUSTRIAL TECHNOLOGY- METAL ASSOCIATED THEORY TOPIC5. WELDING & BRAZING SAFETY PRECAUTIONS SAFETY PRECAUTIONS WELDING & BRAZING BLOWPIPE WELDING & BRAZING BLOWPIPE

2. WELDING EQUIPMENT After steel components have been cut and shaped they can be joined together. This is known as fabrication. It may be achieved by using mechanical fasteners, such as bolts & rivets, or the parts may be joined together by various soldering and welding methods. All of these processes involve heating the metals to be joined, the varying, according to the particular process. The heat may be applied by the burning of or by using Compressed gases are kept in strong steel–walled They are rented from gas companies, who are responsible for and the cylinders on a regular basis to guarantee their safety. temperature gases electricity. cylinders. filling testing GAS WELDING EQUIPMENT Spark arrestor This safety device is fitted between the hose and the blowpipe.

3. SAFETY PRECAUTIONS The cylinders are available in several sizes, e.g.,, and each cylinder is colour coded to indicate the type of gas they contain. The threads on fuel gas fittings are handed and the threads on non-fuel gas fittings are handed. E or D left right What precautions should be taken with cylinders? What particular precautions should be taken with oxygen cylinders? What particular precautions should be taken with acetylene cylinders? Cylinder taps should only be turned on turn to enable them to be turned off quickly in an emergency. Hoses and fittings should be checked regularly for and wear & tear. Cylinders should be chained upright. Valves must be closed when not in use. Keep oil away from oxygen fittings. Acetylene bottles must remain upright. one full damage Pressure gauge Contents gauge Adjusting knob Hose connection Cylinder connection

4. WELDING & BRAZING BLOWPIPE TipMixing chamberFuel valve Oxygen valve Handle Lighting the Blowpipe 1.Point the tip upwards and away from flammable objects. 2.Turn on the fuel and light with a flint. 3.Slowly open the oxygen valve and adjust to a neutral flame. ALWAYS WEAR GOGGLES WHEN USING THE BLOWPIPE CARBURISING FLAME OXIDISING FLAME NEUTRAL FLAME feather Small cone

5. BRAZING Brazing (also known as bronze welding) is a non fusion welding process. This is because the parent metals do not melt, only the metal. Brazing is a popular method of joining metals, and thin metals. It does not require as much heat as welding. Describe the preparation needed to make a successful brazed joint. filler dissimilar 1.Shape the parts to be brazed so they are a good “fit”. 2.Clean the metal in the vicinity of the join with abrasive cloth. 3.Apply a suitable flux where the filler is to be applied. Clear goggles are suitable when brazing. What is the filler rod used for brazing, at what temperature does it melt, and how does it work. How do you know when the parent metal is hot enough to apply the filler rod? What purpose does the flux perform? Tobin bronze melts above 550 0 and flows into the grain boundaries of the parent metal. When it is dull red it will melt the bronze as it is touched to the joint. It cleans the metal and prevents further corrosion.

6. GAS FUSION WELDING Gas fusion welding requires temperatures than brazing because the parent metal melts as well as the filler metal. For this reason oxy-acetylene equipment is used. The parent metal and the metal must be the composition. What type of eye protection should be used when gas fusion welding? higher filler same Approved shaded welding goggles protect the eyes against sparks, heat and bright light. 1.Point the tip upwards and away from flammable objects. 2.Turn on the fuel and light with a flint. 3.Slowly open the oxygen valve and adjust to a neutral flame. Describe the procedure for lighting the oxy-acetylene torch. Oxygen Acetylene 50kPa

7. GAS FUSION WELDING GAS WELDING A BUTT JOIN blowpipe Filler rod

8. ELECTRIC ARC WELDING This type of welding uses electricity to melt the parent metal and a filler metal. A transformer converts the mains power supply by the voltage, and the amperage. decreasing increasing SAFETY SAFETY 1.Use a full-faced helmet with the correct shaded lens. 2.Cover unprotected skin to avoid burn from ultraviolet rays. 3.Avoid welding in damp conditions. 4.Shield your work from other workers, children and pets. transformer +ive -ive What function does the flux coating on the welding electrode/rod perform? It prevents oxidisation of the metal during the welding process.

9. ELECTRIC ARC WELDING DOWN-HAND ARC WELDING THE FOUR MAIN VARIABLES TO A SUCCESSFUL WELD 1.The Amperage. In general, the higher the amperage the higher the temperature. 2.Angle of Rod. This will influence the depth of penetration and the effective strength. 3.Speed of Traverse. If the rod is moved too quickly the parent metal will not melt sufficiently. 4.Length of the Arc. A shorter arc produces a neater, penetrating weld with minimal distortion. Core wire Gaseous shield slag Flux coating Arc stream Molten pool 20 0 -30 0 Tack weld electrode CROSS-SECTIONAL VIEW PICTORIAL VIEW