Millwright Level 1 Practice Exam

Carburizing flames are rich in which gas?

1. Hydrogen

2. Acetylene

3. Propane

4. Butane

The correct answer is: Acetylene

Carburizing flames are defined by a higher concentration of acetylene gas. This type of flame is used in welding and cutting processes where a higher carbon content is desired, as it can introduce additional carbon to the metal being worked on. Acetylene, with its unique properties, plays a significant role in producing these flames because it burns with a richer carbon content compared to other fuel gases. This characteristic enables it to create both the necessary heat and a suitable reducing atmosphere that is essential for carburizing processes, where carbon is absorbed into the surface of steel to enhance its hardness and wear resistance. In contrast, the other gases mentioned do not provide the same carburizing effects as acetylene. Hydrogen is not a primary component of carburizing flames; rather, it is a product of other chemical reactions. Propane and butane are commonly used fuel gases for welding and other applications, but they do not have the same high carbon content as acetylene and do not produce a carburizing flame. Hence, acetylene is the appropriate choice for describing the gas-rich nature of carburizing flames.