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Oxyacetylene Torches. Oxyacetylene is a combination of the words oxygen and acetylene. It refers to the equipment and processes where 2 gases are used together. (In our set up we use MAPP gas and oxygen.) MAPP = methylacetylene-propadiene
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Oxyacetylene Torches
Oxyacetylene is a combination of the words oxygen and acetylene. It refers to the equipment and processes where 2 gases are used together. (In our set up we use MAPP gas and oxygen.) MAPP = methylacetylene-propadiene A portable oxyacetylene rig includes a cart, cylinders, valves, regulators, gauges, hoses, & torch assemblies. Torch is an assembly that mixes gases and discharges them to support a controllable flame. A gas cylinder is a long round tank with extremely thick walls built to hold gases under pressure. Valve is a device that allows gas to flow from cylinder. Regulator is device that keeps the pressure of flowing gas at a constant rate. Gauge is mounted on a regulator to measure and indicate pressure in the hose, tank, or manifold.
Check valves prevent a flame from reaching gas in the cylinder. Hoses are flexible lines that carry gases. Red = fuel gas Green = oxygen
Oxygen Cylinders • Always green in color • Have right-handed threads • Made of high carbon steel • Extruded (made out of one piece of metal) • Full tank has a pressure of 3360 psi • Oxygen in a cylinder is 97% pure • Double-seated valve made of brass so it’s soft and self-seals • Oxygen speeds up the burning process • Inspected with a hydrostatic (water pressure) inspection every 10 years and stamped on tank when passed • Open all the way and SLOWLY • Threaded ring on top oxygen cylinder holds cap on (never attempt to move without cap on!) • Tank owners’ names are stamped on top of cylinder by the rings • Never use oil or grease on or around oxygen equipment • Never use oxygen to blow dirt off clothing or equipment
Acetylene Cylinder • Always red in color • Full tank is 250 psi • Left-handed threads are identified by groove on hex • Unstabilized (aceytlene in its natural state) is dangerous above 15 psi • Porous material absorbs aceytlene in the cylinder • Acetone stabilizes acetylene • Cylinder valves made of brass because it doesn’t spark • Safety device is fusible plug (temperature above 212 degrees F) • Visual inspection every time it’s filled • Never use laying on its side • Only open ¼ turn
ReGULATORS • Reduce cylinder pressure to adjustable, safe constant line pressure • A metallic filter in the stem of the gauge to prevent damage to the hose. • Turning the regulators t-screw to the right increases the working pressure • Backing out t-screw all the way will stop working pressure • Regulator gauge closest to the cylinder indicates tank pressure • Oxygen regulator provides a 3360 psi bursting disk
Basic Info when Using Torches • Work area must be cleared of all flammable materials • First step before using a torch outfit is to crack each cylinder valve one at a time to clear away any dirt or dust before connecting the regulators and lines • Light the torch with a striker • Check valves are used to prevent back flow • Flash arrestors are used to prevent both back flow and back flash • Back fire is a loud pop • Back flash is burning in the handle • Minimum distance between cutting area and torch outfit should be at least 10 feet • When bleed the hoses, bleed them on at a time
When shutting down a torch outfit, bleed the hoses before backing out the regulator t-screws • Size of a tip is determined by the hole diameter of it (hole is 1/3 of plate thickness) • The large heating tip is called a rosebud • When using a tip cleaner to clean a torch tip, always allow a small amount of gas to flow • Always cap cylinder before removing it from the cart • Safety device on the hose is a check valve • Welding tip size corresponds to flame size • Tip cleaners are rods with rough edges designed to remove soot, dirt, or metal residue from the hole in the tip
Shutting Down a Torch System • Close main valves (Acetylene first; Oxygen second) • Bleed hoses one at a time • Back out t-screws • Close handle valves • Remove tip and replace the nut • Coil hoses
3 Types of Flames Carburizing Flame: coolest flame; 5,000 degrees F; used to weld lead and case hardening; hot inner core with a white-hot acetylene feather and blue outer cone Neutral Flame: 5900 degrees F; light blue inner core and darker blue to colorless outer cone; most commonly used flame Oxidizing Flame: hottest flame; 6300 degrees F; inner cone has purplish tint and more pointed; loudest flame; used for welding copper and zinc base metals