Gas Welding 2 Flashcards
What determines the amount of heat that is put into a weld by an oxy-acetylene torch?
The size of the orifice in the torch tip
What is the difference in the appearance of an oxidizing flame, a neutral flame, and a reducing flame produced by an oxy-acetylene torch?
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.
What is one method of minimizing distortion when making a long butt weld?
Skip welding minimizes 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
What is meant by tack welding?
Tack welding is the use of small welded spots to hold the material together until the final bead is run
Why must thick plates of metal be preheated before they are welded?
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
What must be done to an aircraft structure after it has been welded while clamped in a heavy jig or fixture?
It must be normalized by heating it to a uniform red heat and allowed to cool slowly in still air
Why is it important that all traces of the welding flux be removed after a piece of aluminum or magnesium is welded?
Welding flux is corrosive and it must be removed to keep the metal from corroding
What is the difference between brazing and welding?
In brazing, the base metal is not melted, but is covered with a low-melting-point allow. In welding, the base metal is melted.
What kind of flame should be used when gas welding aluminum?
A soft, neutral oxy-,hydrogen flame
What is an acceptable acetylene line pressure to use when welding with an oxy-acetylene rig?
About 5 psi
What kind of flame should the bead penetrate the material when welding two pieces of steel with a butt weld?
The joint should have 100% penetration
What is meant by a soft flame?
A soft flame is one that is made when the pressures of the gases are low enough that the flame does not make a noise and does not blow the puddle
What must be done to an aircraft fuel tank before it can be repaired by welding?
The gasoline fumes must all be purged from the tank by running live steam through it for at least 30 minutes, by soaking in hot water, or by filling it with nitrogen or carbon dioxide
