Dale Crane's Oral and Practical Exam Guide: Airframe; Welding questions with correct answers

What are the two fuel gases most generally used for gas welding? CORRECT ANSWER Oxygen and acetylene What fuel gases are used for welding aluminum? CORRECT ANSWER Oxygen and hydrogen What are two types of torches used in gas welding? CORRECT ANSWER Balanced-pressure torches and injector torches -The injector torch uses fuel gas at pressures between just above 0 and 2 psi. This torch is typically used with propane and propylene gas. High-pressure oxygen comes through a small nozzle inside the torch head and pulls the fuel gas along with it via a venturi effect. The low-pressure injector torch is more prone to flash back. The equal pressure torch is the most commonly used torch for oxy-acetylene welding. It has a mixing chamber and uses acetylene fuel at 1-15 psi. The flame is easy to adjust and there is less chance of flashback with this torch. There are several small lightweight torches of this type that are ideal for aviation welding projects. The Smith AirlineTM and the Meco MidgetTM torches are small enough to be used in close con ned areas, lightweight enough to reduce fatigue during long welding sessions yet, with the appropriate tips, are capable of welding 0.250-inch steel. (FAA-H-8083-31, Vol. 1, Ch. 05) What color lenses are used for gas welding steel? CORRECT ANSWER Green or brown What color lenses are used for welding aluminum? CORRECT ANSWER Blue