Practice Test Geeks(CFS) Certified Fastener Specialist Practice Test
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Torque & Tension Specifications Flashcards

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

Read the first 7 Torque & Tension Specifications flashcards as text

  1. A fastener specification calls for 'prevailing torque' measurement. What does this assess?

    Answer: The frictional resistance torque of the locking element before clamp load is developed

    Prevailing torque is the resistance offered by the locking feature (e.g., nylon insert, distorted thread) before the fastener engages the joint surface.

  2. According to VDI 2230 guidelines, the recommended bolt utilization rate for controlled tightening is approximately:

    Answer: 70–90% of proof strength

    VDI 2230 recommends using 70–90% of the fastener's proof strength to maximize clamp load while maintaining a safety margin.

  3. What is the effect of increasing the grip length of a bolt on joint stiffness?

    Answer: Decreases joint stiffness

    A longer grip length means a more compliant (less stiff) bolt spring, which improves resilience to dynamic loads but reduces joint stiffness.

  4. When converting ft-lb to N·m for a torque specification, which conversion factor is correct?

    Answer: 1 ft-lb = 1.356 N·m

    1 ft-lb equals 1.356 N·m; dividing by 1.356 converts N·m back to ft-lb.

  5. A torque audit (check torque) is performed after installation. The fastener moves at 95% of the original torque. What does this indicate?

    Answer: The fastener likely has adequate preload within acceptable scatter

    Movement at 90–105% of specification torque during an audit typically indicates acceptable installation; significant shortfall suggests relaxation or improper initial torque.

  6. Which tightening method provides the most accurate and consistent bolt preload?

    Answer: Hydraulic tensioner (bolt elongation method)

    Hydraulic tensioners apply direct axial load and measure elongation, bypassing friction variables entirely, giving ±5% or better preload accuracy.

  7. What is 'embedment relaxation' in a bolted joint?

    Answer: Gradual plastic flattening of surface asperities after initial tightening

    Surface asperities on mating faces plastically deform after torquing, causing micro-settling and a loss of 5–10% of initial preload.