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40 Cards in this Set
- Front
- Back
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What are the two fuel gases most generally used for gas welding? |
Oxygen and acetylene.
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What fuel gases are used for welding aluminum?
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Oxygen and hydrogen.
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What are two types of torches used in gas welding?
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Balanced–pressure torches and injector torches.
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What color lenses are used for gas welding steel?
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Green or brown.
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What color lenses are used for gas welding aluminum?
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Blue.
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Why is it important that the pressure of the gas in acetylene cylinder be kept low?
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Acetylene gas becomes unstable when it is kept under pressure of more than about 15 psi.
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What determines the amount of heat that is put into a weld by an oxy–acetylene torch?
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The size of the orfice in the torch tip.
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What is the difference in the appearance of an oxidizing flame, a neutral flame, and a reducing flame produced by an oxy–acetylene torch?
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An oxidizing flame has a pointed inner cone, and the torch makes a hissing noise. A neutral flame has a rounded inner cone, and there is no feather around the inner cone. A reducing flame has a definite feather around the inner cone.
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What is one method of minimizing distortion when making a long but weld?
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Skip welding minimized distortion. Tack weld the materials together and then complete the welds between the tacks, starting at a tack and working back toward the finished weld.
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What is meant by tack welding?
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Tack welding is the use of small welded spots to hold the material together until the final bead is run.
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Why must thick plates of metal be preheated before they are welded?
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Preheating is a method of controlling the expansion and contraction of the metal being welded. Preheating minimizes the stresses that are caused when welding thick metal.
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What must be done to an aircraft structure after it has been welded while clamped in a heavy jig or fixture?
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It must be normalized by heating it to a uniform red heat and allowed to cool slowly in still air.
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Why is it important that all traces of the welding flux be removed after a piece of aluminum or magnesium is welded?
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Welding flux is corrosive and it must be removed to keep the metal from corroding.
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What is the difference between brazing and welding?
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In brazing, the base metal is not melted, but is covered with a low–melting–point alloy. In welding, the base metal is melted.
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What kind of flame should be used when gas welding aluminum?
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A soft, neutral oxy–hydrogen flame.
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What is an acceptable acetylene line pressure to use when welding with an oxy–acetylene rig?
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About 5 psi.
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What kind of flame should be used when gas welding stainless steel?
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A slightly carburizing flame.
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How much should the bead penetrate the material when welding two pieces of steel with a butt weld?
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The joint should have 100% penetration.
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What is meant by a soft flame?
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A soft flame is one that is ade when the pressures of the gases are low enough that the flame does not make a noise and does not blow the puddle.
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What must be done to an aircraft fuel tank before it can be repaired by welding?
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The gasoline fumes must all be purged from the tank by running live steam through it for at least 30 minutes, by soaking it in hot water, or by filling it with nitrogen or carbon dioxide.
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What is another name for GTA welding?
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TIG welding.
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What type of shielding gases are used for GTA welding?
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Helium and argon.
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Why is GTA welding preferred over oxy–acetylene welding for building and repairing welded steel tube aircraft structure?
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The heat is concentrated in the weld and does not cause as much distortion as gas welding.
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What is the function of the inert gas used in GTA and GMA welding?
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The inert gas forms a shield to keep oxygen away from the weld puddle so oxides cannot form and weaken the weld.
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What is used as the electrode in GTA welding?
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A small–diameter tungsten wire.
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What are three types of power that can be used for GTA welding?
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DC–straight polarity, DC–reverse polarity, and AC.
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Which type of power provides the greatest heat and deepest penetration in GTA welding?
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DC–straight polarity.
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Which type of power is used for GTA welding aluminum and magnesium?
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DC–reverse polarity.
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What type of repair can be used when a steel structural tube is dented to more then 1/4 of its circumference?
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A patch may be welded over the damage.
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What type of repair can be used when a steel structural tube is dented at a cluster?
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A patch may be welded over the damaged area with fingers extending up along each member of the cluster.
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What is the preferred method of splicing a new piece of tubing into a structure?
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An inner sleeve splice.
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How is the inner sleeve tube held in the structural tube until the gap is welded?
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It is held in place with rosette welds.
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What is one limitation of using an outer–sleeve splice in an aircraft structure?
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This type of splice is not suitable where it would cause a bulge in the fabric.
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How should the ends of an outer–sleeve be cut?
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Cut it with a 30° fishmouth.
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What is the function of the flux used in soldering?
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Flux covers the cleaned and heated metal to keep oxygen away from it so oxides cannot form. Oxides keep the solder from adhering to the surface of the metal.
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What kind of solder is recommended for soldering electrical wires?
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60/40 resin–core solder.
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What is the composition of 60/40 solder?
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60% tin and 40% lead.
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What is the difference between soldering and brazing?
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Soldering is a method of joining metal parts with a molten nonferrous alloy that melts at a temperature below 800°F but lower than the melting temperature of the metal on which it is used.
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Why must acid–core solder never be used on electrical wire?
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The acid causes the wire to corrode.
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What determines the strength of a soldered joint?
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The mechanical connection of the joint, not the solder. |
