NCCCO Wire Rope Inspection and Replacement 1 — Questions and Answers
Question 1: When inspecting wire rope on a crane, what are 'valley breaks' and why are they particularly serious?
- Wire breaks occurring in the valleys between strands — they are hidden from easy view and indicate advanced fatigue requiring immediate removal from service (Correct answer)
- Surface breaks visible on the crown of each strand due to abrasion
- Breaks caused by chemical corrosion along the rope's outer surface
- Breaks found only at the end terminations of the rope
Correct answer: Wire breaks occurring in the valleys between strands — they are hidden from easy view and indicate advanced fatigue requiring immediate removal from service
Valley breaks occur in the contact zones between strands (valleys), hidden from easy view. They indicate internal fatigue and typically occur before crown breaks, making them a critical condition requiring removal from service.
Valley breaks are fractures in individual wires located at the contact point between adjacent strands. Because they occur inside the rope structure, they are difficult to detect visually during routine inspection. ASME B30.5 and manufacturer guidelines treat valley breaks as a serious condition indicating advanced cyclic fatigue. Finding any valley breaks typically warrants immediate removal from service regardless of the total count.
Question 2: Wire rope has a measured diameter of 0.94 inches but its nominal (rated) diameter is 1 inch. Should this rope be removed from service?
- Yes — a reduction greater than 1/16 inch below nominal for 7/8-inch to 1-1/8-inch ropes requires removal per ASME B30.5 (Correct answer)
- No — reduction in diameter is cosmetic and does not affect load capacity
- Only if the reduction exceeds 1/8 inch below nominal
- Only if accompanied by visible wire breaks
Correct answer: Yes — a reduction greater than 1/16 inch below nominal for 7/8-inch to 1-1/8-inch ropes requires removal per ASME B30.5
ASME B30.5 requires wire rope removal when the diameter is reduced more than 1/16 inch below nominal for ropes in the 7/8-inch to 1-1/8-inch range. A 0.06-inch reduction on a 1-inch rope meets this removal threshold.
Diameter reduction in wire rope results from internal core failure, wire breakage, or severe corrosion reducing the effective cross-section. ASME B30.5-5.4.3 removal criteria include: for rope diameters up to 3/4 inch — reduction of more than 3/64 inch; for 7/8 inch to 1-1/8 inch — reduction of more than 1/16 inch; for 1-3/16 to 1-1/2 inch — reduction of more than 3/32 inch. A 1-inch rope reduced to 0.94 inch has a 0.06-inch reduction, meeting the removal threshold.
Question 3: What does 'bird-caging' in a wire rope indicate, and what action is required?
- The outer strands have expanded outward from the core due to shock loading or severe reverse bending — the rope must be removed from service immediately (Correct answer)
- Normal rope stretch under heavy loads that disappears when the load is removed
- Internal core slippage that can be corrected by re-tensioning the rope
- A rope manufacturing defect visible only in new rope
Correct answer: The outer strands have expanded outward from the core due to shock loading or severe reverse bending — the rope must be removed from service immediately
Bird-caging occurs when outer wire strands splay outward from the rope's core, resembling a bird cage. It results from sudden shock loading, kinking, or running over a too-small sheave. The rope has lost its structural integrity and must be removed from service.
Bird-caging is caused by torsional imbalance forces that separate the rope's strands from the core. It permanently disrupts the lay of the wire rope, reducing its capacity unpredictably. ASME B30.5 lists bird-caging as a condition requiring immediate removal from service. The damage cannot be reversed by any re-tensioning or re-laying process — the rope must be scrapped and replaced.
Question 4: Which end termination is typically used for permanent attachment of wire rope to a crane drum or dead end anchor to achieve full rated breaking strength?
- Swaged (pressed) or spelter socket terminations, which achieve 100% of the wire rope's rated breaking strength (Correct answer)
- Three-bolt wire rope clips (clamps), which are used for all permanent terminations
- Simple loop-back with tape binding for light duty permanent connections
- Wedge socket terminations, which achieve 70 to 75% of wire rope strength
Correct answer: Swaged (pressed) or spelter socket terminations, which achieve 100% of the wire rope's rated breaking strength
Swaged sockets and spelter (zinc-poured) sockets achieve 100% efficiency — the full rated breaking strength of the wire rope — making them the preferred permanent terminations for crane applications where safety is critical.
Termination efficiency is a percentage of the rope's catalog breaking strength. Swaged and spelter sockets achieve 100%. Wire rope clips achieve approximately 80% when correctly applied with the proper number of clips at correct spacing. Wedge sockets achieve 75-80%. For crane hoist lines and structural dead ends, swaged or spelter socket terminations are preferred because they develop full rope strength and do not require field installation skill.
Question 5: When installing wire rope clips (clamps) on a wire rope, what is the correct clip orientation rule?
- Never saddle a dead horse — the clip saddle bears on the live (loaded) rope end and the U-bolt bears on the dead (short) end (Correct answer)
- The U-bolt bears on the live rope end for maximum grip
- Clips may be oriented in any direction as long as the torque specification is met
- Only one clip is required if it is a heavy-duty forged type
Correct answer: Never saddle a dead horse — the clip saddle bears on the live (loaded) rope end and the U-bolt bears on the dead (short) end
The mnemonic 'never saddle a dead horse' means the saddle (flat bearing surface) of the clip always bears on the live (load-carrying) rope end, never on the dead end. Reversing this reduces clip efficiency by up to 40%.
Wire rope clips must be installed with: (1) saddle on the live rope, U-bolt on the dead end, (2) correct number of clips per the manufacturer's specification for that rope diameter, (3) correct spacing between clips (typically 6-7 rope diameters), and (4) proper torque. The number of clips, spacing, and orientation are all specified in ASME B30.26 and the Wire Rope Technical Board's handbook. After initial loading, clips must be re-torqued.
Question 6: How should wire rope be stored on a job site to prevent damage before being installed on a crane?
- On reels or coils in a dry, covered area off the ground, away from chemicals and extreme heat, with end caps to prevent unraveling (Correct answer)
- Directly on the ground, covered with a tarp weighted at the edges
- In tight figure-eight loops to save space and prevent the rope from tangling
- Hanging vertically from a wall hook at one end of the coil
Correct answer: On reels or coils in a dry, covered area off the ground, away from chemicals and extreme heat, with end caps to prevent unraveling
Wire rope should be stored on reels or coils in a clean, dry area elevated off the ground to prevent corrosion, contamination, and mechanical damage. End caps prevent strand unraveling.
Improper storage is a major cause of premature wire rope degradation. Ground moisture causes corrosion. Chemical contact (fuels, acids, concrete) attacks both the wire and the core. Kinking from improper coiling creates permanent damage before the rope is even installed. ASME B30.5 and manufacturer guidelines recommend: horizontal storage on original reels or in coils, covered but ventilated, off the ground on dunnage, away from chemicals, and with end caps or tape to prevent strand separation.
NCCCO Wire Rope Inspection and Replacement 1
When inspecting wire rope on a crane, what are 'valley breaks' and why are they particularly serious?