NCCCO Rigging Techniques & Equipment Inspection 5 — Questions and Answers
Question 1: A rigger is preparing to lift a load using a synthetic roundsling. The sling color is purple. What is the vertical rated capacity of this sling?
- 2,100 lbs
- 4,200 lbs
- 6,600 lbs (Correct answer)
- 10,600 lbs
Correct answer: 6,600 lbs
Per ASME B30.9 color coding for synthetic roundslings, a purple sling has a vertical rated capacity of 6,600 lbs.
Question 2: What condition is described when a wire rope strand is pushed out of its normal position due to a kink being pulled through a block?
- Bird-caging (Correct answer)
- Core protrusion
- Lang lay failure
- Valley break
Correct answer: Bird-caging
Bird-caging occurs when a wire rope is subjected to sudden shock or a kink is pulled through a sheave, causing the outer strands to flare outward like a bird cage.
Question 3: According to NCCCO rigging standards, what is the minimum design factor (safety factor) required for rigging hardware such as hooks and shackles?
- 2:1
- 3:1
- 4:1 (Correct answer)
- 5:1
Correct answer: 4:1
ASME B30.9 requires a minimum design factor of 4:1 (breaking strength to working load limit) for rigging hardware including hooks and shackles.
Question 4: When landing a load on wooden dunnage, why should the sling be kept under slight tension before the final set-down?
- To prevent the load from sliding sideways
- To allow the rigger to inspect the sling while loaded
- To ensure the hook stays centered over the load
- To prevent the sling from being pinched under the load (Correct answer)
Correct answer: To prevent the sling from being pinched under the load
Keeping slight tension on the sling during final set-down prevents it from being trapped and damaged under the load when the load contacts the dunnage.
Question 5: Which of the following is an acceptable practice when using an eye bolt for rigging?
- Applying a side load to a regular eye bolt up to 50% of its rated load
- Using a shouldered eye bolt for angular loads (Correct answer)
- Threading an eye bolt only halfway into its tapped hole
- Loading a regular eye bolt at a 45-degree angle
Correct answer: Using a shouldered eye bolt for angular loads
Shouldered (or collared) eye bolts are designed to accept angular loads, while regular eye bolts must only be loaded in line with the shank.
Question 6: A rigger notices that a hook's latch does not spring back into the closed position after being depressed. What is the correct action?
- Use the hook only for vertical lifts where the latch cannot open
- Remove the hook from service until repaired (Correct answer)
- Secure the latch with tape for the current lift
- Reduce the load to 50% of the hook's rated capacity
Correct answer: Remove the hook from service until repaired
A hook with a malfunctioning latch must be removed from service because the latch is a safety device that prevents the load from accidentally disengaging.
Question 7: What is the effect on a sling's working load limit when the sling angle (measured from horizontal) decreases from 90° to 30°?
- The WLL increases because the sling carries more of the load
- The WLL decreases because horizontal tension in each sling leg increases (Correct answer)
- The WLL stays the same regardless of sling angle
- The WLL doubles because the load is shared between two legs
Correct answer: The WLL decreases because horizontal tension in each sling leg increases
As sling angle decreases from vertical (90°), the tension in each sling leg must increase to support the same load, reducing the effective working load limit; at 30°, tension nearly doubles.
NCCCO Rigging Techniques & Equipment Inspection 5
A rigger is preparing to lift a load using a synthetic roundsling.
The sling color is purple.
What is the vertical rated capacity of this sling?