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

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

• A. Red core
• B. Orange part of flame
• C. Blue outer flame
• D. Neutral flame

Answer: (B)

In oxy-fuel welding the flame has two regions: a blue inner cone and a surrounding luminous zone. The secondary flame is the orange part of the flame—the outer, yellow-orange region that glows because of soot formed when the fuel is richer than the oxidizer. This outer, luminous portion is what you’re identifying as the secondary flame, and it appears distinctly different from the blue, non-luminous inner core used for the main heating. The neutral flame is typically a balanced blue flame without a strong orange outer zone, so the orange region specifically points to the secondary flame.

In oxy-fuel welding the flame has two regions: a blue inner cone and a surrounding luminous zone. The secondary flame is the orange part of the flame—the outer, yellow-orange region that glows because of soot formed when the fuel is richer than the oxidizer. This outer, luminous portion is what you’re identifying as the secondary flame, and it appears distinctly different from the blue, non-luminous inner core used for the main heating. The neutral flame is typically a balanced blue flame without a strong orange outer zone, so the orange region specifically points to the secondary flame.