NCCCO Wire Rope Inspection and Replacement 5 — Questions and Answers
Question 1: What is the correct procedure for determining a wire rope's 'lay length' during inspection?
- Measure the distance between two adjacent broken wires
- Measure the axial distance for one strand to make one complete helical revolution around the rope (Correct answer)
- Count the number of wires in a single strand cross-section
- Measure the total rope length from termination to termination
Correct answer: Measure the axial distance for one strand to make one complete helical revolution around the rope
One rope lay is the axial distance along the rope in which one strand completes a full 360-degree revolution around the rope core.
Question 2: When replacing wire rope, what is the primary purpose of 'pre-forming' a new rope before installation?
- To increase the rope's diameter to match the drum groove
- To permanently shape each wire and strand into its helical position, reducing rotation tendency and improving fatigue life (Correct answer)
- To remove the manufacturer's protective coating before lubrication
- To check for internal broken wires before the rope is placed in service
Correct answer: To permanently shape each wire and strand into its helical position, reducing rotation tendency and improving fatigue life
Pre-forming shapes the wires and strands into their final helical positions during manufacture, reducing residual stress and the tendency to rotate or unlay under load.
Question 3: According to OSHA 29 CFR 1926.1413, who is qualified to perform the monthly wire rope inspection on a crane?
- Any crane operator who has completed a safety orientation
- A qualified person as defined by the standard (Correct answer)
- The crane's original equipment manufacturer representative only
- Any OSHA-licensed rigger regardless of crane experience
Correct answer: A qualified person as defined by the standard
OSHA 1926.1413 requires that monthly wire rope inspections be performed by a qualified person who has specific training, knowledge, and experience in wire rope inspection.
Question 4: What type of wire rope damage results from the rope repeatedly rubbing against a fixed object or the drum flange?
- Fatigue fractures at the crown of strands
- Abrasion causing flat spots and reduced wire diameter on the outer wires (Correct answer)
- Internal corrosion between the core and outer strands
- Peening damage on the inside of the rope
Correct answer: Abrasion causing flat spots and reduced wire diameter on the outer wires
Repeated contact with a hard surface causes abrasive wear, creating flat spots on the outer wire crowns and reducing cross-sectional area.
Question 5: A wire rope shows 'fatigue fractures' with transverse breaks at the wire crowns. What operating condition most commonly causes this?
- Prolonged exposure to saltwater corrosion
- Repeated bending over sheaves or drums with inadequate D/d ratio (Correct answer)
- Overloading the rope once with a static load
- Improper fleet angle causing rope twist
Correct answer: Repeated bending over sheaves or drums with inadequate D/d ratio
Fatigue fractures at wire crowns are caused by repeated cyclic bending stress from running over sheaves or drums, especially when the D/d ratio is too small.
Question 6: When installing new wire rope on a crane drum, what is the correct method to avoid introducing a twist or kink?
- Uncoil the rope on the ground and drag it to the crane
- Unreel the rope off a reel that rotates on a stand, or uncoil from a coil by rotating the coil on a mandrel (Correct answer)
- Cut the rope into sections and splice them together at the drum
- Pull the rope off a stationary coil lying flat on the ground
Correct answer: Unreel the rope off a reel that rotates on a stand, or uncoil from a coil by rotating the coil on a mandrel
Rope must be paid off a rotating reel or rotating coil to prevent twisting; pulling rope off a stationary flat coil introduces one twist per loop.
Question 7: What does the term 'wire rope efficiency' refer to when selecting a rope for a specific crane application?
- The percentage of the rope's breaking strength retained after accounting for sheave friction losses
- The ratio of the rope's actual load capacity to its catalog breaking strength, considering efficiency losses from termination type and reeving (Correct answer)
- The lubrication interval required to maintain rated strength
- The corrosion resistance rating compared to a standard galvanized rope
Correct answer: The ratio of the rope's actual load capacity to its catalog breaking strength, considering efficiency losses from termination type and reeving
Wire rope efficiency accounts for strength reductions introduced by the termination method and multi-part reeving, yielding the actual usable load capacity.
NCCCO Wire Rope Inspection and Replacement 5
What is the correct procedure for determining a wire rope's 'lay length' during inspection?