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CPM - Certified Plant Mechanic Welding and Fabrication Techniques Flashcards

6 cards from real CPM practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. What is the operating principle of a plasma cutter used in plant fabrication and maintenance?

    Answer: Uses an ionized high-velocity gas jet to cut electrically conductive metals

    Plasma cutting passes an electrical arc through a gas (air, nitrogen, or argon) to create a plasma jet hot enough to melt and blow through conductive materials.

  2. In oxy-acetylene cutting, what is the minimum safe oxygen concentration that must be maintained in a confined work area?

    Answer: 19.5%

    OSHA requires a minimum of 19.5% oxygen in a work environment; below this level the atmosphere is oxygen-deficient and dangerous to workers.

  3. What type of weld joint is formed when two pieces of metal are placed end-to-end in the same plane?

    Answer: Butt joint

    A butt joint joins two pieces in the same plane along their edges and is commonly used on pipe, plate, and structural members.

  4. What is the primary cause of porosity in a completed weld bead?

    Answer: Gas trapped in the weld pool during solidification

    Porosity results when hydrogen, oxygen, or nitrogen gas becomes entrapped in the solidifying weld metal, forming voids that weaken the weld.

  5. What is the purpose of back purging with inert gas when welding austenitic stainless steel pipe?

    Answer: Protect the inside (root) of the weld from oxidation and sugaring

    Back purging displaces oxygen from the pipe's bore so the root pass is not oxidized, preventing 'sugaring' and maintaining corrosion resistance in the HAZ.

  6. In welding terminology, what does the term 'penetration' refer to?

    Answer: Depth to which fusion extends into the base metal from the weld surface

    Penetration describes how deeply the weld fusion zone extends into the base metal; insufficient penetration creates a weak joint that may fail under load.