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🇨🇦 456A · BLOCK D · ~20% OF THE EXAM

GTAW (TIG Welding) — Welder (456A) Practice Questions

GTAW (TIG Welding) makes up about 20% of the 456A Welder Red Seal exam. Below are 6 free practice questions from this block, each with the answer and a plain-English explanation of why it is right.

Practice all 15 GTAW (TIG Welding) questions →

Free GTAW (TIG Welding) practice questions

  1. 1.GTAW (TIG) uses what type of electrode?

    • A.Consumable wire
    • B.Non-consumable tungsten electrode with separate filler rod added by hand✓
    • C.Flux-coated rod
    • D.Self-shielding wire

    Why: Tungsten: extremely high melting point (3422°C). Does not melt into the weld (non-consumable). Filler rod is added separately by hand. Produces highest quality welds.

  2. 2.Tungsten contamination of the weld pool happens when:

    • A.Normal operation
    • B.The tungsten touches the molten puddle or filler rod — requiring regrinding✓
    • C.Argon flow is correct
    • D.The arc is too short

    Why: Touching tungsten to puddle: tungsten transfers to the weld (inclusion) and contaminates the tip. Stop, break off contaminated tip, regrind to a point on a dedicated grinding wheel.

  3. 3.The purpose of back-purging stainless steel GTAW root passes:

    • A.Cooling
    • B.Prevent oxidation (sugaring) on the root side by displacing air with argon✓
    • C.Adding colour
    • D.Increasing speed

    Why: Argon purge on the root side prevents chromium oxidation. Sugar (black oxide) = weak, corroded root. Purge until O₂ is below 1% (use O₂ monitor or purge for calculated time).

  4. 4.Tungsten electrode tip shape for DC welding on steel:

    • A.Flat
    • B.Ground to a point (15-30° included angle) for focused, stable arc✓
    • C.Ball shape
    • D.Square

    Why: Pointed tip: precise, focused arc ideal for steel/stainless on DCEN. Grind longitudinally (not radially) on a dedicated wheel. Balled tip only for AC aluminum.

  5. 5.Post-flow (gas after-flow) on a GTAW torch protects:

    • A.The regulator
    • B.The hot tungsten and solidifying weld from oxidation after the arc stops✓
    • C.The gas lens
    • D.The filler rod

    Why: Post-flow: argon continues after arc stops to shield the cooling weld and tungsten. Typically 5-15 seconds. Without it: tungsten oxidizes (contaminates), weld discolours.

  6. 6.When TIG welding stainless steel, the filler rod should be:

    • A.Carbon steel
    • B.Matching or slightly overalloyed grade (e.g., ER308L for 304, ER316L for 316)✓
    • C.Pure tungsten
    • D.Flux-coated

    Why: Match or overalloy: ER308L for 304SS, ER316L for 316SS. 'L' = low carbon (prevents sensitization). ER309L for dissimilar (carbon to stainless) joints.

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Other 456A exam blocks

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