Rigging Techniques & Equipment Inspection Flashcards
6 cards from real NCCCO practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Rigging Techniques & Equipment Inspection flashcards as text
What is the 'D/d ratio' and why does it matter for wire rope?
Answer: The ratio of the sheave or drum diameter (D) to the rope diameter (d) — smaller ratios accelerate rope wear and reduce rope life
A small D/d ratio means the rope bends sharply around a small radius, creating more internal stress and fatigue. Industry minimums ensure rope bends are gradual enough to prevent premature failure.
When should synthetic (nylon/polyester) slings NOT be used?
Answer: In environments with excessive heat, chemical exposure, sharp edges without protection, or near welding/cutting operations
Synthetic slings are vulnerable to heat (melting), chemicals (degradation), sharp edges (cutting), and UV exposure. They should be protected from these hazards or replaced with wire rope or chain slings.
What is a 'turnbuckle' used for in rigging?
Answer: To adjust tension in guy wires, braces, or tie-downs by screwing or unscrewing the threaded ends
Turnbuckles provide adjustable tension by lengthening or shortening when the barrel is rotated. They're commonly used on guy wires, tie-downs, and bracing where precise tension adjustment is needed.
What is the minimum sling angle recommended for safe lifting?
Answer: Any angle is safe
Below 30° from horizontal, the tension in each sling leg increases rapidly. At very low angles, sling loads can exceed their rated capacity even though the total load is within limits. Most standards recommend maintaining at least 30° angles.
A chain sling shows a stretched link. What should be done?
Answer: Remove from service immediately — stretched links indicate the chain has been overloaded and is permanently weakened
Stretched links indicate the chain has been loaded beyond its elastic limit, permanently weakening the metal. The sling must be immediately removed from service and destroyed or returned for professional evaluation.
What determines the 'center of gravity' of a load and why is it important for rigging?
Answer: The point where the load's weight is evenly distributed, which determines how the load hangs and whether it tilts when lifted
The center of gravity determines how a load behaves when lifted. If the rigging doesn't account for an off-center CG, the load will tilt, potentially slipping from slings or creating uncontrolled swing.