ISO 24467:2020 Crane Wire Rope Inspection & Maintenance Guide
ISO 24467:2020 "Cranes — Wire Ropes — Maintenance and Inspection" is the dedicated standard for wire rope maintenance and inspection on cranes. Building on ISO 4309 Wire Rope Inspection Standard, it expands and refines discard criteria, daily inspection methods, maintenance cycles, and record-keeping requirements to cover wire rope safety management across all crane types.
Refined Discard Criteria for Wire Ropes
ISO 24467:2020 refines and expands the discard criteria set out in ISO 4309 Wire Rope Inspection Standard. Number of broken wires — within one lay length (approximately 6–7 times the wire rope diameter), a regular lay wire rope must be scrapped when visible wire breaks exceed 10% of the total number of wires; for a lang lay wire rope, the threshold is 5%. Wire breaks caused by bending fatigue in pulley groove and drum groove zones are more critical than those in straight sections — each break in these zones counts as two.
Wire break concentration — when breaks cluster within a localized area (one-third of the rope circumference), three concentrated breaks trigger close monitoring (weekly inspection), and six breaks require scrapping. Diameter reduction — when diameter loss from wear or corrosion exceeds 7% of the nominal diameter (measured in the pulley groove zone), the rope must be scrapped. Surface wear — scrapping is required when outer wire wear exceeds 40% of the wire diameter. Corrosion — visible pitting or flaking rust, regardless of wire breaks, mandates scrapping. The standard also introduces a residual strength coefficient — when diameter changes cannot be measured directly, electromagnetic testing may be used to assess residual strength, and scrapping is required at ≤85%.
Daily Inspection Methods and Intervals
The standard defines a three-tier inspection system. Daily Inspection — performed by the operator before each shift, involving visual inspection of the rope's overall condition: wire breaks, wear, corrosion, deformation, and lubrication status. Periodic Inspection — conducted monthly by dedicated maintenance personnel over the full rope length, with particular attention to contact zones with pulleys and drums, areas near terminations, and regions prone to fatigue. Thorough Examination — performed annually by a certified wire rope inspector, including electromagnetic testing as part of a comprehensive assessment.
Inspection methods include visual inspection (ensuring adequate lighting, using magnifiers or borescopes where necessary to examine concealed rope sections), hand-on inspection (gloved hands running along the full rope length to detect wire breaks and indentations), and instrument-based inspection (electromagnetic detectors measuring diameter variations and wire break defects). The standard recommends marking reference zones in pulley groove and drum groove areas, with each inspection focusing on diameter changes and wire breaks in these marked sections. After each inspection, a permanent tag with the inspection date and inspector's name must be attached to the rope end.
| Inspection Level | Frequency | Personnel | inspection content | Inspection Tools |
|---|---|---|---|---|
| Daily Inspection | Per Shift | operator | Overall Appearance/wire break | Visual |
| Periodic Inspection | Monthly | Maintenance Personnel | Full-Length Detailed/Critical Areas | Magnifying Glass/Caliper |
| thorough examination | Annual | certified inspector | EMT+Comprehensive Assessment | electromagnetic testing Instrument |
| special inspection | Installation/Overhaul After | certified inspector | New Rope Verification | Full Tool Kit |
Maintenance & Lubrication
The standard sets out systematic requirements for wire rope maintenance. The lubrication interval should be determined by the operating environment: once a month for normal indoor conditions, once a week in dusty environments, and once every two weeks for outdoor or marine service. Before lubricating, remove dirt and old grease from the rope surface using a dedicated cleaning agent — never gasoline or other solvents that can corrode the wire rope. The lubricant must match the type recommended by the rope manufacturer; commonly used wire rope grease should comply with JG/T 148.
Drip or spray application is recommended to ensure the lubricant penetrates evenly between strands and individual wires. Take care to prevent lubricant from dripping onto brake friction surfaces, which could cause braking slippage, or onto conductor rails, which could impair electrical conductivity. The standard also specifies storage requirements: wire ropes should be kept in a dry, well-ventilated warehouse, away from corrosive substances. Ropes stored for extended periods should be re-lubricated every 3 months to prevent internal corrosion.
Record Management & Traceability
The standard emphasizes complete inspection and maintenance records for wire ropes. A maintenance record must be established for each rope, including rope number, specification and model, manufacturer, installation date, initial diameter, length, and scrapping date. Each inspection record should capture: inspection date, inspector, inspection point, type and severity of defects found (number of broken wires, locations, diameter measurements, corrosion grading), recommended corrective actions, and the next inspection date. Records must be retained for at least the entire service life of the rope, from installation through scrapping.
Kelude supplies a wire rope maintenance log with every crane, allowing users to document each inspection at the required intervals and attach inspection tags to the rope end. The standard also recommends RFID electronic tag management for critical ropes — such as those on man-lifting cranes and large, high-importance cranes — enabling digital lifecycle traceability.
| Record Items | content requirements | Records Frequency | Retentionrequirements |
|---|---|---|---|
| Basic Information | Serial Number/Model/Date | Entered at Installation | Throughscrapping+6Months |
| Daily Inspection | wire break/Wear/Status | Per Shift | Monthly Summary |
| Periodic Inspection | Full-Length Diameter/wire break Statistics | Monthly | Archived for Reference |
| Lubrication Records | Date/Lubrication Agent/Personnel | Each Time Lubrication | Filed |
| discard record | scrapping Reason/Date | scrapping When | Filed |
FAQ
Q: Why do discard criteria for wire breaks differ between regular lay and lang lay wire ropes?
A: In lang lay wire ropes, steel wires within the same strand run parallel, so stress concentrates more sharply around a wire break, making each individual break more critical. In regular lay ropes, the crossing wire pattern allows adjacent wires to share the load after a break. For this reason, the discard threshold for lang lay ropes (5%) is stricter than for regular lay ropes (10%).
Q: What does electromagnetic testing (EMT) detect, and why use it?
A: EMT detects internal wire breaks, corrosion, and cross-section loss without being affected by surface grease or dirt. When visual inspection cannot reliably assess internal damage—such as severe internal corrosion or hidden wire breaks—EMT is the most dependable evaluation method. Ropes with residual strength at or below 85% must be scrapped.
Q: How is the lubrication interval for wire ropes determined?
A: Lubricate once a month under normal indoor conditions, once a week in dusty environments, and every two weeks for outdoor or marine service. Old grease must be removed before relubrication. Lubricant must never drip onto brake surfaces. Kelude recommends using a dedicated drip-type wire rope lubricator.
Q: How long should wire rope inspection records be kept?
A: Keep records for at least six months after the rope is removed from service and scrapped. An electronic information management system is recommended for long-term storage. The RFID electronic tag on each wire rope can store everything from basic data to the complete inspection history, enabling full life cycle management.
