Transcript Document
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 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 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 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 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 1)Close main valves (Acetylene first; Oxygen second) 2)Bleed hoses one at a time 3)Back out t-screws 4)Close handle valves 5)Remove tip and replace the nut 6)Coil hoses Acetylene Oxygen Cutting 5-8 psi 30-40 psi Welding 5-8 psi 15-20 psi Heating 8-10 psi 50 psi 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