Questions and Answers
Which of the following are used as fuel gases for OFC? (Select all that apply)
What does OFC stand for?
Oxy-fuel cutting
While making a cut with OFC, the inner cones of the flame should be held how far away from the surface of the metal?
1/16" - 1/4"
What is required before making a good manual OFC? (Select all that apply)
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With OFC, what is the result of a preheat flame that is too small/low? (Select all that apply)
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OFC: Slag that is hard to chip off the bottom of the plate occurs because: (Select all that apply)
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OFC: Distortion is caused by:
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What metal is easiest to weld with oxyacetylene?
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With OFW, the size/diameter of the filler metal used has the following effect(s): (Select all that apply)
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The weld pool when OFW:
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OFW: What should happen as one finishes the end of the weld? (Select all that apply)
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When welding a thicker plate to a thinner plate with OFW, what should you do?
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What gas burns the hottest?
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What is the kindling temperature?
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Steel melts at what temperature?
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What material is readily cut with OFC?
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Which of the following is common to both OFW and OFC? (Select all that apply)
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Flashback can occur because of: (Select all that apply)
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OFC: What is kerf?
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Using a VICTOR brand, what is the correct tip size for OFC on 1/2" plate?
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What are the main advantages of OFC? (Select all that apply)
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OFW would be best for what thickness of plate? (Select all that apply)
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A weld defect is: (Select all that apply)
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All good welds should have a good appearance.
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Not all welds with good appearance are sound.
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R65 and RG45 are fillers that can be used for OFW.
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Propane is the most frequently used fuel gas.
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The OFC process is a result of the metal being rapidly melted and blown away.
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Inspecting the drag lines of a cut can indicate correctly or incorrectly made cuts.
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Restricting the working pressure of ___________ helps reduce the risk of explosion.
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Study Notes
OFC (Oxy-Fuel Cutting)
- Fuel gases used include Natural Gas, Propylene, Acetylene, and MAPP.
- Inner cones of the flame should be held 1/16" to 1/4" away from the metal surface.
- Essential prerequisites for manual OFC include neutral flame adjustment, clean center hole in the tip, and proper gas pressures.
- If the preheat flame is too small/low, it can cause wandering cutting stream, require slower travel speed, and prolong cutting time.
- Issues like hard-to-chip slag can arise from too much preheat, incorrect oxygen pressure, wrong tip size, or a dirty cutting tip.
- Distortion occurs due to localized expansion and internal stresses; it can be minimized with proper techniques and sequencing.
- The kerf refers to the gap created by the diameter of the oxygen stream.
OFW (Oxy-Fuel Welding)
- Mild steel is the easiest metal to weld with oxyacetylene.
- Filler metal size influences the weld pool temperature and bead size.
- The weld pool is shielded by CO2 gas and benefits from silicon deoxidizers present in filler metals.
- As the weld ends, it is important to pause and add filler metal to fill the crater and slant the torch for cooling.
- Direct heat of the torch toward the thicker plate when welding different thicknesses.
- Acetylene burns the hottest among available gases, with steel melting at approximately 2700°F.
- OFW is suited for 1/8" plate or thinner, often for small jobs or repairs.
Welding and Cutting Safety
- Flashback may occur if mixed fuel burns inside the torch tips or hoses, or if the cutting or welding tips overheat.
- R65 and RG45 are acceptable fillers for OFW.
- Inspecting drag lines can indicate the quality of a cut.
- Restricting working pressure of acetylene can reduce explosion risks.
General Welding Knowledge
- A weld defect can include porosity, craters, or any unwelcome material in the weld area.
- All good welds should have an appealing appearance, but not all aesthetically pleasing welds are structurally sound.
- Propane is not the most frequently used fuel gas; that title goes to acetylene.
- The OFC process does not involve rapid melting and blowing away of metal, contrary to some misconceptions.
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Test your knowledge on Oxy-fuel Cutting (OFC) and related concepts with these flashcards. Each card presents a key term or question that is crucial for mastering welding techniques. Perfect for learners in the Welding 170 course.
