In oxy-fuel welding, which feature describes the primary flame?

In oxy-fuel welding, which feature describes the primary flame?

• A. Orange part of flame
• B. Blue cone on torch
• C. Pinkish core of flame
• D. Blue teeth on torch

Answer: (D)

The main idea is identifying which part of an oxy-fuel flame provides the focused, hottest heat used for welding. The primary flame is the blue cone that forms directly at the torch tip. This inner blue cone is where combustion is most complete and heat is concentrated, making it the part you use to weld efficiently and with clean heat. The lighter, luminous orange portion is the secondary, outer envelope of the flame. It’s cooler and can contain soot from incomplete combustion, so it’s not what you rely on for the welding heat. Terms like pinkish core or “blue teeth” aren’t standard descriptions of the flame’s main heat-producing region, so they don’t describe the primary flame.

The main idea is identifying which part of an oxy-fuel flame provides the focused, hottest heat used for welding. The primary flame is the blue cone that forms directly at the torch tip. This inner blue cone is where combustion is most complete and heat is concentrated, making it the part you use to weld efficiently and with clean heat.

The lighter, luminous orange portion is the secondary, outer envelope of the flame. It’s cooler and can contain soot from incomplete combustion, so it’s not what you rely on for the welding heat. Terms like pinkish core or “blue teeth” aren’t standard descriptions of the flame’s main heat-producing region, so they don’t describe the primary flame.