6.2 Wire Rope Sling Inspection and Removal Criteria

6.2 Wire Rope Sling Inspection and Removal Criteria

Quick Answer: Remove a wire rope sling from service for broken wires beyond criteria, birdcaging/kinks/crushing, heat damage, severe corrosion, core protrusion, damaged eyes or fittings, or a missing/illegible ID tag. Do not “use it carefully” or cut the WLL by half in the field—quarantine it.

Wire rope slings are common on construction and industrial sites because they handle abrasion and heat better than many synthetics and offer high strength in a compact package. They still fail catastrophically when outer wires break, the core protrudes, or the rope structure is distorted. NCCCO Level I inspection questions lean heavily on recognizing defects and applying removal criteria in the language of ASME B30.9 and OSHA (e.g., 1910.184 / 1926.251 concepts).

How to Inspect a Wire Rope Sling (Frequent Check)

Work systematically so you do not miss localized damage:

1. Identification — Read the tag. Confirm rated load for the hitch type you plan to use (vertical, choker, basket ratings may differ). No tag or unreadable tag → out of service.
2. Entire length of each leg — Walk the rope slowly. Pay special attention to areas that were previously choked, sat on edges, or rubbed fittings.
3. Outer wires and strands — Look for broken wires (ends may be needle-sharp—use care), worn flats, and corrosion between strands.
4. Rope structure — Check for birdcaging, kinks, crushed sections, waviness, core protrusion, or unlaying.
5. Eyes and splices — Flemish eyes, mechanical splices, hand tucks (where used), thimbles, and seizing.
6. End fittings — Sockets, sleeves, master links, hooks attached as part of the sling assembly.
7. Disposition — Accept, or tag and remove.

Lighting matters. Mud, grease, and paint can hide broken wires; clean enough of the rope to see the wires you are judging. Do not spin a dirty rope against bare skin—broken wire ends cut deeply.

Defect Catalog — What You Are Looking For

Broken Wires

Broken wires are the classic wire-rope rejection topic. They often concentrate where the rope bends over a hook, pin, or load edge, or where a choker hitch has worked the same zone repeatedly.

Exam-level criteria (widely tested OSHA / B30-style language for many running ropes and wire rope slings):

A rope lay is the length along the rope in which one strand makes one complete turn around the core. You do not need to be a metallurgist on the written exam, but you must know that broken-wire counts are measured in a lay length, not “somewhere on the whole sling,” and that one strand with five breaks can condemn the sling even if total breaks on the rope are under ten.

Product-type note: Braided multi-part slings and some specialty constructions can have additional or different criteria in the governing B30.9 section and manufacturer instructions. On the exam, when a scenario cites the classic “10 in one lay / 5 in one strand” language, apply that concept. In the field, follow the manufacturer and current standard for that exact sling type.

Birdcaging

Birdcaging is a distortion where outer strands open outward like a birdcage, often from sudden release of tension, shock unloading, or forced rotation against a fixed end. It indicates the rope’s geometry is permanently disrupted. Remove from service—you cannot “massage” strands back into a load-rated rope.

Kinks

A kink is a sharp permanent bend where strands and wires are permanently deformed. Kinks often form when a loop is pulled tight or when the rope is improperly uncoiled. A kinked section is a stress riser and a rejection condition for sling service.

Crushing and Flattening

Crushing flattens the rope’s cross-section—common when a load sets down on a sling, a vehicle runs over it, or the rope is pinched in a sheave or under a load corner. Crushed rope has lost structural shape; remaining strength is not something a rigger field-calculates. Remove from service.

Heat Damage

Heat damage may show as blueing, blackening, fused wires, loss of lubricant with scorched appearance, or nearby evidence of welding/cutting sparks. Wire rope that has been heated beyond manufacturer limits can lose strength without dramatic broken-wire counts. Evidence of heat damage → remove from service.

Corrosion

Light surface rust after outdoor use may be cleaned and reassessed, but severe corrosion, deep pitting, or corrosion that freezes wires together and hides broken wires is a reject condition. Corrosion inside the rope (especially with fiber cores or poor lubrication history) can be worse than it looks. When corrosion raises doubt, remove from service and escalate to competent-person evaluation—do not guess remaining capacity.

Core Protrusion

Core protrusion (core popping out between strands or at ends) means the rope’s internal support is displaced. It is a serious structural defect. Remove from service.

Wear and Abrasion

Outer wires can wear into flat spots from rubbing on loads or structures. OSHA-style language often references wear or scraping of about one-third the original diameter of outside individual wires as a removal concept for wire rope. Severe abrasion that cuts or thins wires rapidly is treated the same as structural damage: out of service.

Missing or Illegible Tags

If you cannot read the sling’s rated load and required identification, you cannot select it legally or safely. Missing or illegible identification = remove from service.

Removal Criteria Quick Reference (Wire Rope Slings)

Eyes, Splices, and Fittings

Wire rope slings commonly use:

Broken wires often concentrate at the eye crotch and at the entry to a sleeve or socket. Do not inspect only the middle of the leg.

Hooks that are part of a sling assembly follow hook removal ideas (throat opening increase, twist out of plane, cracks)—detailed in the hook inspection chapter. If the hook is defective, the assembly is out of service even if the rope body looks fine.

D/d, Edges, and Why Damage Starts

Wire rope is sensitive to tight bends. Choking on a small diameter or pulling over a sharp corner creates high localized bending stress and abrasion—exactly where broken wires and crushing appear. Edge protection and adequate pin/hook diameter (D/d awareness) are use topics, but they explain why inspection focuses on choke zones and contact points. After any lift where the rope was shock-loaded, side-loaded hard against a corner, or heated, re-inspect before reuse.

What Level I Does Not Do

• Does not re-rate a damaged sling to a lower WLL by personal judgment
• Does not cut out a bad section and re-eye a sling in the field unless working under manufacturer-authorized processes (generally not Level I scope)
• Does not ignore a few broken wires because “it still looks strong”
• Does not use a sling with no tag because “we know it’s a half-inch rope”

Storage and Care That Protect the Next Inspection

• Store off the ground, away from chemicals and excessive heat
• Avoid running over slings with equipment
• Uncoil and handle rope to prevent kinks
• Keep incompatible chemicals and weld spatter off the rope
• Return slings to designated racks so damaged units can be segregated

Exam Focus

Written items often give a short defect description (“birdcage after shock unload,” “five broken wires in one strand in one lay,” “tag unreadable,” “blue heat marks near the eye”) and ask for the correct action. The safe, testable answer is almost always remove from service. Distractors include continuing at reduced load, waiting for the annual periodic date, or repairing with wire and tape. Choose the answer that matches criteria-based removal and immediate segregation.