NCCCO Wire Rope Inspection and Replacement 2 — Questions and Answers

Question 1: What is the minimum number of randomly distributed broken wires in one rope lay that requires wire rope removal from service per ASME B30.5?

3 broken wires
6 broken wires (Correct answer)
10 broken wires
12 broken wires

Correct answer: 6 broken wires

ASME B30.5 requires wire rope removal from service if there are 6 or more randomly distributed broken wires in one rope lay, or 3 or more in one strand.

ASME B30.5 (Mobile and Locomotive Cranes) establishes specific criteria for wire rope removal from service. One of the key criteria is broken wire count: wire rope must be removed from service if there are 6 or more randomly distributed broken wires in one rope lay length, or 3 or more broken wires in any one strand within one lay length. A rope lay (also called a lay length) is the linear distance along the rope in which one strand makes one complete helical revolution around the core. For a typical 6-strand wire rope, this is roughly 6 to 8 times the rope diameter. These thresholds are not arbitrary — they are based on engineering analysis of wire rope residual strength. When wire breaks accumulate, the remaining wires must carry the same load, increasing stress in each wire and accelerating further wire fatigue and failure. Inspectors must count broken wire ends (each break has two ends) and divide by two to get the number of broken wires. Broken wires in critical areas such as end terminations, within 1 rope diameter of socketed ends, or in running ropes at contact points with sheaves and drums may require immediate removal even below the 6-wire threshold. NCCCO exam questions on wire rope removal criteria are common and require precise knowledge of the ASME B30.5 standards.

Question 2: Wire rope with kinks should be:

Used only for light lifts below 25% of rated capacity
Carefully straightened using a hydraulic press before reuse
Immediately removed from service and discarded (Correct answer)
Inspected annually and removed only if kinks worsen

Correct answer: Immediately removed from service and discarded

Kinked wire rope must be immediately removed from service. Kinking permanently damages the internal structure of the rope, drastically reducing its strength and fatigue life.

A kink in wire rope is formed when a loop in the rope is pulled tight, causing permanent deformation of the strands and wires. Once kinked, the individual wires and strands are displaced from their proper helical positions, and the rope's load-sharing geometry is permanently disrupted. The rope can never be safely returned to its original strength and flexibility. Attempting to straighten kinked rope by any means — whether by hand, with tools, or with a hydraulic press — does not restore the rope's integrity and may cause additional wire damage. The internal wire damage from kinking is not visible from outside the rope and cannot be assessed without destructive testing. Kinks typically occur when wire rope is uncoiled or unreeled improperly, when it is allowed to form a loop that is then tensioned, or when it is subjected to sudden jerking loads that cause internal strand crossing. Proper rope handling — always unreeling from a reel and never uncoiling a coil by pulling from the inside — prevents kinking. ASME B30.5 and OSHA 1926.1413 both list kinking as a removal-from-service criterion. NCCCO examination questions on wire rope inspection commonly include scenarios involving kinked rope to ensure operators know that such rope must never be returned to service under any circumstances.

Question 3: What does corrosion inside a wire rope indicate, and how can it typically be detected?

Surface rust only; detected by visual inspection of the outer strands
Internal wire deterioration; detected by loss of rope diameter, stiffness changes, or discoloration at rope interstices (Correct answer)
Normal aging; no action required unless ropes are over 5 years old
Chemical contamination; detected by smell during inspection

Correct answer: Internal wire deterioration; detected by loss of rope diameter, stiffness changes, or discoloration at rope interstices

Internal corrosion is a serious form of wire rope deterioration that affects the core and inner wires, detectable by reduction in rope diameter, increased stiffness, or rust-colored discharge between strands.

Internal corrosion in wire rope is particularly dangerous because it attacks the core and inner wires where it cannot be directly observed. It is caused by moisture penetration, aggressive environments (saltwater, acids, chemical exposure), or the deterioration of the rope's lubricant over time. Left unchecked, internal corrosion can dramatically reduce rope strength while the outer surface appears relatively intact. Indicators of internal corrosion include: reduction in rope diameter compared to nominal size (as internal wires deteriorate and collapse), increased rope stiffness or loss of flexibility, rust-colored discharge or deposits visible in the valleys between strands (interstices), and pitting on outer wires that suggests moisture has penetrated the rope. Regular lubrication is the primary defense against internal corrosion. Rope lubricants penetrate the interstices and coat internal wires, displacing moisture and forming a protective barrier. However, over-lubrication can mask developing corrosion and break patterns, complicating inspection. ASME B30.5 requires wire rope to be removed from service when internal corrosion is detected through any inspection means. OSHA regulations also identify internal corrosion as a removal criterion. NCCCO candidates must understand both the hazards of internal corrosion and the inspection indicators that suggest its presence, as well as the limitations of visual inspection in detecting internal damage.

Question 4: When measuring wire rope for diameter reduction, at what percentage of nominal diameter reduction must rope be removed from service?

1% reduction
3% reduction (Correct answer)
5% reduction
10% reduction

Correct answer: 3% reduction

Wire rope must be removed from service when its actual diameter has reduced by more than 3% from the nominal (catalog) diameter, as specified in ASME B30.5.

ASME B30.5 specifies that wire rope must be removed from service when the actual measured diameter has decreased by more than 3% from the nominal (specified) diameter. For example, a 1-inch nominal diameter rope that measures less than 0.970 inches must be removed from service. Diameter reduction is a significant indicator of rope deterioration. It can result from internal wire wear due to friction between wires and strands, loss of core integrity (fiber core compression or wire rope core deterioration), internal corrosion (wire metal loss), or loss of rope lubrication causing compaction of the rope structure. Measuring wire rope diameter correctly requires using a properly calibrated set of calipers with wide-opening jaws that span at least two opposite outer strands. The rope should be measured at multiple locations along its length, particularly in areas subject to highest wear (at sheave contact points and on the drum). Measurements should be taken on the crown of two opposite outer strands. A wire rope that has lost 3% or more of its diameter has also lost a significant portion of its metallic cross-sectional area (the actual load-bearing material). This directly translates to reduced breaking strength. NCCCO examinations include specific questions about diameter reduction criteria to ensure operators understand this quantifiable removal standard and can apply it during required inspections.

Question 5: What is 'bird caging' in wire rope, and what causes it?

Protective cage installed around the wire rope to prevent damage
Outward flaring of wire rope strands caused by sudden shock load or reverse bending (Correct answer)
Pattern of corrosion pits that resemble a cage on outer strands
Special wire rope configuration used in multi-part line arrangements

Correct answer: Outward flaring of wire rope strands caused by sudden shock load or reverse bending

Bird caging occurs when wire rope strands and/or wires flare outward from the rope body, typically caused by shock loads or reverse bending, permanently damaging the rope's structure.

Bird caging is a condition in which the wire rope strands and outer wires flare outward from the rope body, creating a shape that resembles a bird cage. It is caused by shock loads (sudden application of load beyond the rope's working load), reverse bending (the rope being bent in opposing directions over sheaves), or the rope being wound on too small a sheave or drum radius for its construction. When a shock load is applied, the helical wires and strands in the rope are forced to straighten momentarily. If the shock is severe enough, the strands do not return to their proper helical positions and instead spring outward. This permanently destroys the rope's load distribution geometry. Bird-caged rope must be immediately removed from service. The outwardly flared strands cannot properly carry load, and the damaged section of rope will fail at a load far below the rope's rated breaking strength. No repair or reconditioning is possible. Preventing bird caging involves avoiding shock loading (using controlled acceleration when lifting), ensuring rope is run over sheaves and drums of adequate diameter, and eliminating conditions where rope is subjected to reverse bending at tight angles. NCCCO examination questions on wire rope damage conditions specifically test recognition of bird caging and understanding of its causes and consequences.

Question 6: A wire rope's 'lay direction' refers to:

The direction in which the rope must be reeved through the block and tackle
The direction in which the outer strands are helically twisted around the rope's center (Correct answer)
The path the rope follows from the drum to the load block
The angle at which wire rope contacts a sheave groove

Correct answer: The direction in which the outer strands are helically twisted around the rope's center

Lay direction describes whether the outer strands are twisted in a right-hand (regular) or left-hand (lang's lay) direction as they spiral around the rope's core.

Wire rope lay direction describes the direction in which the outer strands are helically twisted around the rope's central axis. A right-hand lay rope has strands that spiral clockwise from bottom to top when the rope is held vertically, while a left-hand lay rope has strands that spiral counterclockwise. In addition to lay direction, wire rope is also classified by how the individual wires within each strand are laid relative to the strand lay direction. 'Regular lay' (most common) has the wires in each strand laid in the opposite direction to the strand lay. 'Lang's lay' has the wires and strands both laid in the same direction. Lay direction and type affect the rope's resistance to rotation, abrasion resistance, flexibility, and fatigue life. Right-hand regular lay (RHRL) is the most commonly used construction for crane wire rope. Lang's lay ropes offer better abrasion resistance and fatigue life but are more susceptible to unlaying (strand loosening) under certain conditions. Using the correct lay direction is important when installing rope on crane drums. Some crane drum systems (particularly multi-layer drums) require specific lay directions to ensure proper rope spooling and prevent crushed or crushed rope conditions. NCCCO candidates must understand wire rope lay classifications and their practical implications for crane operations.

NCCCO Wire Rope Inspection and Replacement 2

What is the minimum number of randomly distributed broken wires in one rope lay that requires wire rope removal from service per ASME B30.5?