When piercing steel plate with a cutting torch, the cutting oxygen valve should be opened during the preheating of the base metal to provide more heat.

When piercing steel plate with a cutting torch, the cutting oxygen valve should be opened during the preheating of the base metal to provide more heat.

• A. True
• B. False
• C. Only after preheating
• D. Only during cutting

Answer: (B)

The key idea is that the cutting oxygen is used to start and sustain the actual cutting action, not the preheating. When you’re piercing steel with an oxy-fuel torch, you want the preheat flame to warm the metal in a controlled way without blowing hot gas into the surface. That means keeping the cutting oxygen valve closed during the preheating stage so you don’t abruptly oxidize the surface or create excessive heat that can cause unstable preheat or premature ignition. Once the base metal has reached the proper preheat temperature, you then open the cutting oxygen to initiate the cut and keep it flowing as you move through the material. The oxygen helps oxidize the metal in the cut zone and blows away the molten slag, producing a clean kerf. So, opening the cutting oxygen during preheating is not appropriate because it disrupts controlled heating and can lead to unreliable piercing.

The key idea is that the cutting oxygen is used to start and sustain the actual cutting action, not the preheating. When you’re piercing steel with an oxy-fuel torch, you want the preheat flame to warm the metal in a controlled way without blowing hot gas into the surface. That means keeping the cutting oxygen valve closed during the preheating stage so you don’t abruptly oxidize the surface or create excessive heat that can cause unstable preheat or premature ignition.

Once the base metal has reached the proper preheat temperature, you then open the cutting oxygen to initiate the cut and keep it flowing as you move through the material. The oxygen helps oxidize the metal in the cut zone and blows away the molten slag, producing a clean kerf.

So, opening the cutting oxygen during preheating is not appropriate because it disrupts controlled heating and can lead to unreliable piercing.