Welding 170 OFC and OFW Flashcards
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Questions and Answers

Which of the following are used as fuel gases for OFC? (Select all that apply)

  • Propylene (correct)
  • MAPP (correct)
  • Acetylene (correct)
  • Natural Gas (correct)

    • 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)

    <p>Clean center hole in the tip (A), Proper gas pressures (B), Neutral flame adjustment (C)</p> Signup and view all the answers

    With OFC, what is the result of a preheat flame that is too small/low? (Select all that apply)

    <p>Travel speed of cut must be slower (A), It takes longer to make the cut (B), Cutting stream can wander (C)</p> Signup and view all the answers

    OFC: Slag that is hard to chip off the bottom of the plate occurs because: (Select all that apply)

    <p>Incorrect oxygen pressure (A), Wrong tip size for the metal being cut (B), Too much preheat (C), The cutting tip is dirty (D)</p> Signup and view all the answers

    OFC: Distortion is caused by:

    <p>Heat of the cut causing localized expansion and creating internal stresses (A), Cutting techniques and cut sequencing (B)</p> Signup and view all the answers

    What metal is easiest to weld with oxyacetylene?

    <p>Mild steel</p> Signup and view all the answers

    With OFW, the size/diameter of the filler metal used has the following effect(s): (Select all that apply)

    <p>It can change the size of the weld bead (A), It can change the temperature of the weld pool (B)</p> Signup and view all the answers

    The weld pool when OFW:

    <p>Has additional help against oxygen from the silicon deoxidizers in the filler metal (A), Is shielded from the atmosphere by CO2 gas (B)</p> Signup and view all the answers

    OFW: What should happen as one finishes the end of the weld? (Select all that apply)

    <p>Pull the torch up/slant the torch at an angle to allow the puddle to cool (A), Pause and add a little filler metal to fill in the crater (B)</p> Signup and view all the answers

    When welding a thicker plate to a thinner plate with OFW, what should you do?

    <p>Direct the heat of the torch towards the thicker member</p> Signup and view all the answers

    What gas burns the hottest?

    <p>Acetylene</p> Signup and view all the answers

    What is the kindling temperature?

    <p>The temperature at which metal burns</p> Signup and view all the answers

    Steel melts at what temperature?

    <p>2700 deg F</p> Signup and view all the answers

    What material is readily cut with OFC?

    <p>Steel</p> Signup and view all the answers

    Which of the following is common to both OFW and OFC? (Select all that apply)

    <p>Oxygen (A), Neutral flame (B)</p> Signup and view all the answers

    Flashback can occur because of: (Select all that apply)

    <p>When mixed fuel burns inside the torch tip and/or hoses (A), When the welding tip overheats (B), When the cutting tip overheats (C)</p> Signup and view all the answers

    OFC: What is kerf?

    <p>The gap created by the diameter of the oxygen stream</p> Signup and view all the answers

    Using a VICTOR brand, what is the correct tip size for OFC on 1/2" plate?

    <p>0</p> Signup and view all the answers

    What are the main advantages of OFC? (Select all that apply)

    <p>Portable (A), Low cost (B)</p> Signup and view all the answers

    OFW would be best for what thickness of plate? (Select all that apply)

    <p>Small jobs or repairs (A), Plate 1/8&quot; or thinner (B)</p> Signup and view all the answers

    A weld defect is: (Select all that apply)

    <p>Anything that should not be in the weld area (A), Craters (B), Porosity (C)</p> Signup and view all the answers

    All good welds should have a good appearance.

    <p>True (A)</p> Signup and view all the answers

    Not all welds with good appearance are sound.

    <p>True (A)</p> Signup and view all the answers

    R65 and RG45 are fillers that can be used for OFW.

    <p>True (A)</p> Signup and view all the answers

    Propane is the most frequently used fuel gas.

    <p>False (B)</p> Signup and view all the answers

    The OFC process is a result of the metal being rapidly melted and blown away.

    <p>False (B)</p> Signup and view all the answers

    Inspecting the drag lines of a cut can indicate correctly or incorrectly made cuts.

    <p>True (A)</p> Signup and view all the answers

    Restricting the working pressure of ___________ helps reduce the risk of explosion.

    <p>acetylene</p> Signup and view all the answers

    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.

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