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40 Cards in this Set
- Front
- Back
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What are iron based metals called?
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Ferrous
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Oxy-fuel cutting accelerates the process of ______________?
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Oxidization
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What is washing?
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removal of a bolt or rivet with a cutting torch
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What is flame gouging?
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Removal of a narrow strip of surface metal
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What is oxygen lance cutting?
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process of cutting through extremely thick steel
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How thick can you cut with an oxygen lance cutting torch?
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8 feet thick
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The ferrous alloys that present problems for cutting are those with _____________ content
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high carbon
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Does the oxide formed by these alloys during cutting have a higher or lower temperature than the base metal?
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higher
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What are 3 special techniques for dealing with protective slag shields?
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preheating/waster plates/wirefeed
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What is a waster plate?
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low carbon steel plate clamped along the cut line to add more iron to the kerf
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What is the wire feed technique?
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low carbon steel wire fed into the cut
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What are examples of non-ferrous metals that should not be cut with oxy-fuel process?
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aluminum, copper, brass, bronze, magnesium
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What are two major problems created in the base metal by cutting?
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distortion and surface hardening
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What techniques minimize distortion?
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preheating, intermittent cutting and stack cutting
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What is the best way to avoid excessive hardening while cutting?
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slow the rate of cooling by preheating and post heating the base metal
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What shade number should be used for heavy cutting - over 6"
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5 or 6
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What is backfire?
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torch flame backs up into the cutting tip - makes popping sound
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What is flashback?
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backfire goes beyond the tip into the hoses
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How hot of temperature can an oxy-acetylene flame reach
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up to 6300 degrees farenheit
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What is the maximum working pressure for free acteylene?
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103 kPa or 15 psi
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When acetylene reacts with copper it forms ____________?
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Acetylide - a residue even more volatile then acetylene
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What are 3 other common gases used in oxy-fuel cutting?
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Mapp, natural gas and propane
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What is the cutting temperature of Mapp?
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2900 degrees C (5300 degrees F)
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What is the cutting temperature of natural gas?
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2540 degrees C
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What is a neutral flame?
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A flame the burns the fuel completely
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What is the ratio of acetylene to oxygen to generate a neutral flame?
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1 to 1
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What is the ratio of oxygen to Mapp needed to generate a neutral flame?
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2.5 to 1
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What is the pressure inside an oxygen cylinder at room temperature?
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15mPa or 2200psi
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What happens to the pressure inside an oxygen cylinder when the outside temperature increases?
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it increases
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At what pressure does a safety disc rupture on an oxygen cylinder?
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23 mPa or 3360 psi
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Why must acetylene cylinders be kept upright when in use?
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to prevent acetone from flowing into the system
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What are the fusible plugs in acetylene cylinders for?
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They will melt if excessive heat is applied and release the contents of the tank
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What is the draw limit?
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maximum rate at which acetylene can be withdrawn from the cylinder
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What is the draw limit for acetylene cylinders per hour?
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1/7 the volume of the tank
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What is the advantage of a two stage regulator?
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makes the flow of gas more constant and eliminates the need for readjustment of pressure
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What are the common gas hose diameters for oxy-fuel cutting?
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3/16", 1/4", 5/16" and 3/8"
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What is a ferrule?
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a metal ring that is crimped on the end of the hose to secure the connection
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What are the correct steps in assembling an oxyacetylene outfit?
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Secure the cylinders
remove the caps crack the valves attach the regulators install the RFCV connect the hoses open the valves purge the hoses connect the cutting attachment |
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What threads do oxygen cylinders have?
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Right hand
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What threads do acetylene cylinders have?
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Left hand
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