Wire Rope Inspection and Replacement Criteria Flashcards

When inspecting a rotation-resistant wire rope on a mobile crane, what is the ASME B30.5 removal-from-service criterion for broken wires — and why does it differ from standard 6-strand rope?

Answer: 2 randomly distributed broken wires in 6 rope diameters, or 4 broken wires in 30 rope diameters; the multi-layer construction means fewer breaks signal severe internal fatigue

ASME B30.5 imposes a far more stringent standard for rotation-resistant (low-rotation) rope: 2 broken wires in any 6-rope-diameter section OR 4 broken wires in any 30-rope-diameter section. Because rotation-resistant ropes have multiple wire layers wound in opposing directions, a small number of breaks indicates that the complex internal structure has already undergone significant fatigue — structural integrity degrades rapidly from that point. Standard 6-strand rope uses 12 randomly distributed breaks per lay (or 4 in one strand) as its threshold.

A crane inspector finds broken wires occurring at the contact point between adjacent wires within a strand — below the outer surface — rather than at the crown of the outer wires. This type of break is called a valley break. Why is this finding considered especially dangerous compared to a crown break?

Answer: Valley breaks form at the wire-to-wire contact points inside the strand and are hidden from surface view, meaning by the time they are detected, internal fatigue has already progressed significantly

Crown breaks occur on the outer surface of the rope and are relatively easy to spot during visual inspection. Valley breaks, by contrast, form at the internal contact points between wires within a strand — they are concealed beneath the outer wire layer. When valley breaks are finally detected (often only during close tactile inspection or when the rope is bent around a sheave), internal fatigue is already advanced. ASME B30.5 and OSHA both treat any valley break as a serious indicator warranting removal from service because the true extent of internal damage is unknown.

While measuring a 1-inch nominal-diameter running wire rope, an inspector notices a localized section where the rope diameter has INCREASED by approximately 3% compared to its nominal size, even though the outer wires appear undamaged and no broken wires are visible. What is the most accurate interpretation of this finding?

Answer: Internal wire rope core (IWRC) failure causing the strands to displace outward, creating an unsupported, structurally compromised section

A localized diameter increase in a wire rope — sometimes called 'waviness' or 'bulging' — with intact-looking outer wires is a classic signature of internal wire rope core (IWRC) failure. When the core collapses or breaks, the outer strands lose their internal support and splay outward, causing measurable diameter increase in that section. The rope has lost significant structural integrity even though the outer surface may look deceptively normal. This is an immediate removal-from-service condition per ASME B30.5. Thermal expansion and lubrication redistribution do not produce localized diameter increases of this magnitude.

A lattice-boom crawler crane uses standing ropes (pendants) to support the boom. The inspector finds 3 broken wires within a 24-inch span of one pendant. The rope has a nominal diameter of 3/4 inch. Under ASME B30.5, what is the correct action?

Answer: Remove from service immediately; standing ropes must be removed when more than 2 broken wires are found in any 30-rope-diameter section

ASME B30.5 applies a separate, more conservative criterion to standing ropes (pendants, guys, and similar non-running ropes) because they carry sustained static loads rather than cycling over sheaves. The removal threshold is more than 2 broken wires in any 30-rope-diameter section. For a 3/4-inch rope, 30 diameters = 22.5 inches. Three broken wires within a 24-inch span exceeds this criterion and requires immediate removal from service. Applying the running-rope threshold (12 per lay) to standing ropes is a common and potentially fatal error.

During post-incident inspection of a wire rope that passed through a sheave adjacent to a furnace during an industrial lift, the inspector observes that several outer wires exhibit a slight blue-to-straw discoloration and are unusually easy to bend by hand compared to adjacent sections. No broken wires are present and the rope diameter is within tolerance. What is the correct action?

Answer: Remove from service immediately; the discoloration and loss of stiffness indicate annealing (loss of temper), which permanently reduces wire strength regardless of broken-wire count

Annealing occurs when wire rope is exposed to heat sufficient to alter the metallurgical temper of the steel wires. Symptoms include characteristic blue-to-straw oxidation discoloration and abnormal flexibility (wires that feel 'soft' or bend with less resistance than normal). Annealed wire has permanently lost its high-tensile strength — the mechanical properties cannot be restored. ASME B30.5 lists heat damage as a mandatory removal-from-service condition independent of broken-wire counts or diameter measurements. Proof load testing an annealed rope is extremely dangerous and does not restore integrity.

An inspector measures a rotation-resistant wire rope rated at 1 inch nominal diameter and finds that it measures 0.989 inches at one cross-section — a reduction of approximately 1.1%. The rope has zero broken wires and no other visible defects. Under ASME B30.5, what is the required action?

Answer: Remove from service; rotation-resistant ropes must be removed when diameter reduction exceeds 1% of nominal, compared to the 3% threshold for standard 6-strand rope

ASME B30.5 applies a 3% diameter reduction threshold to standard 6-strand wire ropes but a much stricter 1% threshold to rotation-resistant ropes. This reflects the fact that rotation-resistant ropes rely critically on the geometric integrity of their complex multi-layer wire arrangement — even a small reduction in cross-section indicates internal wire failures or severe wear that compromises the rope's ability to resist rotation under load. A 1.1% reduction on a 1-inch rotation-resistant rope exceeds the 1% limit and requires immediate removal, even with zero broken wires. This is one of the most commonly missed inspection criteria in the field.