Gas Welding The burning qualities of gas are used to heat, cut, and weld metals. Compressed gases can be very dangerous. The most popular gases for welding are propane and acetylene. These gases must be mixed with oxygen before they will burn.
Safety Precautions Wear safety goggles or shield at all times. Have the instructor’s permission before using the gas. Store fuel gas cylinders away from the oxygen cylinders. Keep cylinders upright and chained at all times, store in well-ventilated areas. Do not put pressure on the pipes or equipment connected to cylinders. Always check for leaks before using. Never use equipment exposed to grease or oil. Follow specific procedures for turning on or off.
Precautions Cont. Work only in areas free of flammable materials. Always have fire extinguishers nearby. Wear leather gloves and apron. Always screw on caps when nothing is attached. Always point equipment away from people and clothing. Never leave clothing where it can be saturated by fuel gases or oxygen. Learn to recognize combustible fuel odors. Protect gas cylinder storage areas with locked fences or concrete enclosures.
Set Up Design features: –Acetylene cylinder valve protected by a high collar. Turned on and off with a handle. –Acetylene equipment color coded red. –Acetylene couplings have left-hand threads and notched fittings. –Oxygen has heavy caps to cover valves. –Oxygen color coded green. –Oxygen couplings have right-hand threads.
Leak Tests Leak tests should be performed when: –Equipment is first set up. –Cylinders are changed. –Odor of acetylene is present when unit is not in use. To Test: –Put small amount of water in a jar or can. –Add sliver of nondetergent hand soap. –Use 1'' paintbrush to get a soapy lather and apply gently around each fitting and points where gas may escape. –Bubbles will form if there is a leak.
Torches Two Types: –Welding –Cutting Both include a body/handle with hose connections and valves. Tips are screwed on the handle. A cutting assembly can also be attached to the handle. Tips are available in different sizes.
Important Terms Weld—to join by fusion. Fusion—melt together. Gas—any fluid substance that expands without limit. Compress—apply pressure to reduce in volume. Flammable—burns easily. Apparatus—objects necessary to carry out a function.
Terms Cont. Manifold—pipe with 2 or more outlets. Rig—self-contained piece of apparatus assembled to conduct an operation. Oxyacetylene—oxygen and acetylene. Torch—assembly that mixes gases and discharges them to support a controllable flame. Cylinder—long, round tank with extremely thick walls built to hold gases under great pressure.
Terms Cont. Valves and Regulators—devices that control or regulate the flow of the gas. Gauge—measures the pressure in the hose, tank, or manifold. Hoses—flexible lines that carry the gases. Crack the Cylinder—turning the gas on and off quickly to blow any dust from the opening. Purge the Lines—remove undesirable gases.
Terms Cont. Carbonizing Flame—excess of acetylene. Neutral Flame—correct balance of acetylene and oxygen. Oxidizing Flame—excess of oxygen. Tip Cleaners—rods with rough edges designed to clean the hole in the tip. Bleeding the Lines—removing gases from all lines and equipment.