Oxy-Acetylene Flames — Identify the Flame When Acetylene Flow Exceeds Oxygen If the torch is adjusted to deliver more acetylene and less oxygen than a neutral setting, what type of flame results?

Introduction / Context:
Flame settings in oxy-acetylene welding are categorized as neutral, oxidising, and carburising (reducing). Understanding how gas ratios affect flame structure and metallurgical effects is critical to avoid embrittlement, excessive oxidation, or porosity.

Given Data / Assumptions:

• Torch uses acetylene (fuel) and oxygen (oxidizer).
• Adjustment moves to higher acetylene and lower oxygen compared to neutral.
• Observation includes longer feather on the inner cone characteristic of a reducing flame.

Concept / Approach:
A carburising flame has excess acetylene. It shows a pronounced acetylene feather beyond the inner cone and introduces a reducing atmosphere that can carburize or deoxidize the work. This is useful for specific applications (e.g., some alloy brazings), but harmful for others due to carbon pickup or sooty deposits.

Step-by-Step Solution:
Compare gas ratios: acetylene up, oxygen down → rich fuel mixture.Identify visual cue: larger feather on the inner cone → carburising flame.Select the term “carburising”.

Verification / Alternative check:
Flame charts confirm three regimes; carburising occurs on the fuel-rich side of neutrality.

Why Other Options Are Wrong:
Neutral has balanced gas flow.Oxidising has excess oxygen, not acetylene.Other terms listed are not standard oxy-acetylene flame classifications.

Common Pitfalls:
Using a carburising flame on steels can cause sooty welds and carbon enrichment; adjust to neutral unless a procedure requires otherwise.

Final Answer:
carburising