What does it mean if a cutting or welding flame burns inside the torch?

When a cutting or welding flame burns inside the torch, it signifies a flashback. A flashback occurs when the flame from the cutting or welding process travels back into the torch itself, potentially resulting in serious hazards, such as the torch becoming overheated or damaged, and posing a significant risk of fire. The flame should be contained within the nozzle or tip; if it enters the torch, it disrupts normal operation and indicates a problem, such as improper gas mixture or restrictions in gas flow. This situation requires immediate attention to prevent dangerous consequences.

The other choices do not accurately describe the phenomenon of a flame burning inside the torch. While a backfire refers to a momentary flare-up that occurs in the immediate vicinity of the torch, it does not involve a flame moving back into the torch itself. A fire hazard is a general term that denotes any situation that could lead to a fire, but it lacks the specific context of what happens when a flame enters the torch. Effective burning simply indicates that the torch is functioning correctly, which is the opposite of what occurs during a flashback.