456A Oxyfuel Welding & Cutting 2

Question 1

What minimum distance must separate oxygen and fuel gas cylinders in storage, unless a fire-resistant barrier is used?

Accepted Answer

6 m (20 ft)

Answer

Canadian fire codes require oxygen and fuel gas cylinders to be stored at least 6 m (20 ft) apart or separated by a non-combustible barrier at least 1.5 m (5 ft) high to prevent both from being involved in a fire.

Question 2

When cutting mild steel with an oxyfuel torch, what reaction actually performs the cut?

Accepted Answer

Rapid oxidation (burning) of the preheated steel by the cutting oxygen stream

Answer

OFC works by heating the steel to its ignition temperature (~870°C) and then directing pure oxygen to rapidly oxidize (burn) the metal, removing it as iron oxide slag — the metal burns rather than melts.

Question 3

Why cannot aluminum be effectively cut using the standard oxyfuel cutting process?

Accepted Answer

Aluminum oxide (Al₂O₃) has a higher melting point than the base metal, blocking the oxidation cut

Answer

Aluminum oxide (Al₂O₃) melts at approximately 2050°C, far above aluminum's melting point of 660°C, so the refractory oxide layer prevents the progressive oxidation required for OFC to work.

Question 4

What is the purpose of flux when performing oxyfuel welding on cast iron or bronze?

Accepted Answer

To prevent oxidation and chemically remove oxides from the weld pool

Answer

Flux acts as a chemical cleaning agent, dissolving and floating away oxides from the weld pool surface to prevent oxide inclusions and produce a clean, sound fusion bond.

Question 5

What is 'kerf' in the context of oxyfuel cutting?

Accepted Answer

The width of material removed by the cutting process

Answer

Kerf is the slot or groove created by the cutting process — the total width of material consumed and removed from the workpiece during the cut.

Red Seal Welder 456A Practice Test

Red Seal Welder 456A Practice Test

456A Oxyfuel Welding & Cutting 2