Crane Wire Rope Maintenance, Inspection & Discard Criteria
GB/T 5972-2016, "Cranes — Wire Ropes — Care, Maintenance, Inspection and Discard," is the dedicated standard for full life cycle management of crane wire ropes. The standard specifies daily inspection, periodic inspection methods, discard criteria, and maintenance requirements, making it the most critical standard for the safe use of crane wire ropes.
GB/T 5972-2016 is identical to ISO 4309:2010 and serves as the general standard for the care, maintenance, inspection, and scrapping of crane wire ropes. The wire rope is the most critical and wear-prone safety component in a crane's hoisting mechanism — it directly carries the suspended load while undergoing repeated bending and abrasion during operation. Wire rope breakage is one of the most severe safety incidents that can occur on a crane. The standard applies to the daily inspection, periodic inspection, and discard criteria for wire ropes used in all types of cranes, and is a basic standard that operators and maintenance personnel must master. Kelude Heavy Industry selects and configures wire ropes for factory-delivered cranes in accordance with this standard and provides operation and maintenance training for wire rope usage.
Daily Wire Rope Inspection Checklist
The standard specifies that daily inspection of the wire rope is carried out by the operator before each work shift. The inspection method combines visual observation with hand-touch feel to confirm the surface condition of the rope. Inspection content includes: whether the rope is evenly spooled on the drum — uneven spooling causes adjacent wraps to rub against each other, accelerating wear. Whether there are visible wire breaks — if broken wires are found within one lay length, their positions should be marked with an oil-based pen and the count recorded. Whether there is surface wear or corrosion — the wire rope diameter is measured with a caliper at least 2 m from the rope end. The condition of the surface lubricant — dry or missing grease indicates insufficient lubrication and the need for re-lubrication. Whether the rope is properly aligned in the pulley groove — misalignment causes side-wall wear of the groove and crushing deformation of the rope. If the daily inspection reveals a rapid increase in the number of broken wires over a short period or a sudden reduction in rope diameter, a detailed inspection should be arranged immediately.
Lubrication maintenance is also an important part of the daily inspection routine. The standard requires that wire ropes be lubricated regularly based on operating frequency and environmental conditions — generally once per week or every 100 working hours. In high-temperature, dusty, or corrosive environments, the lubrication frequency should be increased to 2–3 times per week. Before lubrication, dirt and old grease should be removed from the rope surface. The lubricant should be a wire-rope-specific grease whose performance matches the rope manufacturer's recommendation, with good penetration and adhesion, and free of corrosive components. During application, the grease should fully penetrate into the rope core and the interstices between strands. Lubrication methods include brushing, spraying, or drip application. After lubrication, the rope surface should be checked for a uniform oil film with no missed areas. Lubricants containing acid or alkali are prohibited, as they accelerate corrosion of the wire rope.
Wire Rope Discard Criteria and Thresholds
The core content of the standard is the discard criteria for wire ropes. The rope must be scrapped if any of the following conditions occurs: wire breaks — when the number of broken wires within one lay length exceeds 10% of the total number of wires (e.g., for a 6×19 construction, more than 6 broken wires within one lay length). Diameter reduction — when the measured rope diameter is reduced by more than 7% of the nominal diameter (more than 3% for rotation-resistant ropes). Corrosion — when visible rust, pitting, or internal corrosion causes a uniform reduction in rope diameter. Deformation — when plastic deformation such as waviness, birdcaging, kinking, flattening, or core protrusion is present. Heat damage — when the rope has been discolored by high-temperature burns or electric arc burns. The standard also specifies that broken wires concentrated in a localized area of a single strand (localized wire break clustering) at the bottom of a pulley groove warrant earlier scrapping than uniformly distributed breaks. For ropes near the drum and pulleys, where bending fatigue concentrates wire breaks, a shortened inspection interval is recommended.
Quantitative indicators for each discard condition are provided in detailed tables within the standard. When assessing wire breaks, a distinction must be made between visible breaks (wire ends protruding from the rope surface) and hidden breaks (wire ends not protruding, detectable only with an electromagnetic flaw detector). Diameter measurement should be taken under no-load conditions at least 2 m from the rope end, measuring in two mutually perpendicular directions and averaging the results. Diameter reduction results from the combined effect of external and internal wear. Corrosion severity assessment requires opening the strands to inspect the internal wire surface condition — internal corrosion is more dangerous than surface corrosion because it is difficult to detect visually. A wire rope service record card should log the number of broken wires, diameter measurements, and key findings from each inspection to support trend analysis. After scrapping and replacement, the new rope's model, specification, manufacturer, and installation date should be recorded.
Wire Rope Storage and Installation
The standard also sets requirements for the storage and installation of wire ropes. Ropes should be kept in a dry, well-ventilated warehouse, away from direct contact with the floor or walls to prevent moisture damage and corrosion. During storage, packaging should be checked periodically for integrity, and any signs of rust must be addressed immediately. Wire rope drums should be placed horizontally on a level surface and must not be stacked. Before installation, cut off 1–2 m from the rope end on the drum before attaching it to the crane drum, as the end section may have been damaged during transport or storage. The rope fixing on the drum must comply with the manufacturer's requirements, using clamping plates or wedges, with a fixing strength of no less than 80% of the rope's breaking force. After installation, the new rope should be run through several cycles under light load to allow the strands to seat evenly. For critical applications—such as hoisting ropes on metallurgical cranes—the standard recommends a breaking force sample test prior to installation to verify that the actual breaking force is not less than the nominal value.
Inspection Intervals and Record-Keeping
Inspection intervals are determined by the operating conditions and work duty of the wire rope. Daily inspections are carried out by the operator each shift. Periodic inspections are performed by maintenance personnel, with the interval determined by the working class: A1–A4: monthly; A5–A6: every two weeks; A7–A8: weekly. For ropes used in high-temperature or corrosive environments, the inspection interval must be reduced to half the normal frequency. The results of each thorough examination must be recorded on the rope's service record card, including: equipment name, rope model, specification, and manufacturer; installation and scrapping dates; inspection date, number of broken wires and their distribution; diameter measurements and wear percentage; corrosion and deformation status; lubrication records; and the inspector's signature. The record card must be retained in the equipment file for at least one year after the rope is scrapped. Trend analysis of recorded data enables prediction of the rope's remaining life, allowing replacement schedules to be planned in advance and preventing sudden fracture incidents.
Wire Rope Discard Criteria Comparison Table
The comparison table below lists the core parameters for wire rope discard criteria, for reference by selection and operation personnel.
| Wire Rope Type | discard criteria Condition | inspection methods | acceptance criteria |
|---|---|---|---|
| regular lay wire rope | Lang Laywire break≥4Strand(10d)/≥8Strand(30d) | Visual Inspection+wire breakdetector | GB/T 5972-2016 |
| lang lay wire rope | Lang Laywire break≥2Strand(10d)/≥4Strand(30d) | Visual Inspection+wire breakdetector | GB/T 5972-2016 |
| wire rope diameter Reduction | Diameter reduction≥nominal diameter7% | vernier caliper Measurement | GB/T 5972-2016 |
| Wire Rope Corrosion | Outer Layer Steel wire Corrosion Visible+wire break | visual inspection+Dimensional Measurement | GB/T 5972-2016 |
| Wire Rope Deformation | Kink/Flattening/Knot/Core Exposure | visual inspection | Immediatelyscrapping |
FAQ: Wire Rope Inspection, Lubrication & Replacement
Q: How many broken wires within one lay length require scrapping?
A: Per ISO 4309, a wire rope must be scrapped when the number of visible wire breaks within one lay length exceeds 10% of the total number of wires. For example, a 6×19 rope construction (114 wires) must be retired if more than 11 wires are broken within a single lay length.
Q: What is the correct way to measure wire rope diameter?
A: Use a vernier caliper to measure the rope diameter at a minimum distance of 2 m from the rope end, with the rope in a relaxed, unloaded state. Take two measurements at right angles to each other and record the average value. The caliper jaws must be positioned across the widest point of the rope — i.e., over the crown of two adjacent strands.
Q: What is the purpose of wire rope lubrication?
A: Wire rope lubrication reduces friction and wear between individual steel wires, prevents internal corrosion, keeps the rope core from drying out, and extends the overall service life of the rope. For best results, use a dedicated wire rope grease specifically formulated for this application.
Q: Must a wire rope with waviness deformation be scrapped?
A: Yes. Waviness deformation indicates permanent damage to the internal rope structure, and continued use may lead to sudden fracture during operation. The acceptance criteria state that a rope must be scrapped when the wave height (amplitude) of the waviness exceeds one-third of the nominal rope diameter.
