A type of welding flows, which is the result of a perfect proportion and mixture of acetylene and oxygen and is used for fusion welding of steel and cast iron, is

Answer: Option D

Neutral flame is type of welding flows, which is the result of a perfect proportion and mixture of acetylene and oxygen and is used for fusion welding of steel and cast iron. The neutral flame is the flame in which the amount of oxygen is precisely enough for burning, and neither oxidation nor reduction occurs. A flame with a good balance of oxygen is clear blue. The reducing and neutral flames are useful in soldering and annealing. Neutral flame has a 1:1 ratio of acetylene and oxygen. It's the most preferred flame for welding.