FAA Aviation Mechanic General (AMG)Materials, Hardware and ProcessesMedium
A technician is performing an oxyacetylene weld repair on a steel tubing fuselage structure. Which flame adjustment should be used to avoid introducing excess carbon or oxygen into the weld?
- ACarburizing flame with a visible excess acetylene feather
- BReducing flame producing a soft, cool blue color
- CNeutral flame with a well-defined, rounded inner cone
- DOxidizing flame with excess oxygen and a hissing sound
Show answer & explanationAnswer & explanation
Correct answer: C. Neutral flame with a well-defined, rounded inner cone
A neutral flame, identified by a sharply defined, rounded inner cone with no excess feather, has a balanced ratio of oxygen and acetylene. This flame does not add excess carbon (as a carburizing flame would) or oxidize the metal (as an oxidizing flame would), making it the correct setting for most aircraft steel welding repairs.
Why the other options are wrong
- A. A carburizing flame has excess acetylene, adding carbon to the weld and weakening it.
- B. There is no standard 'reducing flame' terminology distinct from carburizing in oxyacetylene welding; this describes an incorrect adjustment.
- D. An oxidizing flame has excess oxygen, which burns out alloying elements and weakens the weld.
Neutral Oxyacetylene Flame
A balanced oxygen-to-acetylene flame with a sharply defined, rounded inner cone and no feather, used for most aircraft steel welding to avoid carburizing or oxidizing the weld.
- Identified by a clear, well-defined inner cone
- Balanced mixture of oxygen and acetylene gas
- Preferred flame setting for most ferrous metal aircraft welding
Memory trick: 'Neutral keeps it balanced, no feather, no fuss' - the safe welding flame