CSA Z248:17 tower crane wire rope inspection and removal criteria
What CSA Z248:17 says about wire rope: scope, how often to inspect, what to
inspect and when a rope must come off. Written in our own words with the clause number for each point.
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Scope
The crane rope rules deal with the ropes that hoist loads, move the trolley, or hold up the boom, including pendants. Their construction, grade, strength, size, type and length must match what is set by the original crane maker, or by a rope maker who knows tower crane work, and the original rope specification must be written into the crane manual. 4.11.1
In this standard the word rope means wire rope, unless a clause says otherwise. 3 (definition: Rope)
A tower crane here is a hammerhead, luffing or other tower crane that is put up and taken down for use on different sites, including climbing, telescoping and self-erecting types. 3 (definition: Tower crane)
Every tower crane must be inspected, tested and maintained following the maker's instructions as well as the Clause 6 requirements. 6.1
The broken wire limits in Tables 1 and 2 only apply to rope running on steel sheaves and drums. For rope running fully or partly on synthetic sheaves, or metal sheaves with a synthetic lining, the user must get broken wire limits by asking a competent person as well as the maker of the sheave, drum or crane. 6.5.2.2
Inspection frequency
General maintenance intervals. Maintenance, greasing, lubrication and electrical checks follow the maker's intervals or this standard's, whichever is more often. The crane operator or qualified service staff do them on a schedule and log them in the operator's crane log. 6.4.1
Before erection. Before the crane is erected, every fixed wire rope must be checked for all kinds of deterioration under the rope inspection clause 6.5. 6.4.2 b)
After erection, before service. Once erection is complete and before the crane goes into service, the erector's personnel, with the regular operator if available, do a final inspection. This includes checking every running rope for all kinds of deterioration under Clause 6.5, with the crane manual on hand. 6.4.3 d)
Daily (operator). As part of the operator's daily checks, the load hoist and boom hoist ropes are inspected under Clause 6.5. 6.4.4.1 e)
Daily (frequent) rope inspection. Each day a designated person, who can be the operator, visually checks all load hoist, boom hoist and load trolley rope likely to be used during that day's work, paying particular attention to where the rope attaches to the crane. 6.5.1.2.1
Daily inspection records. Daily inspection results go in the operator's crane log. 6.5.1.2.5
Weekly. Every week, check guy ropes and pendant lines, plus thimbles, ferrules and cable clips, every rope attachment, and the sheaves with their pins and bushings. 6.4.5 d), e), g)
Monthly. Every month, check all running ropes for all kinds of deterioration under the periodic inspection clause 6.5.1.3, and also check drums, sheaves, bearings and mounts. 6.4.6 a), f)
Periodic. The rope maker or a competent person sets how often periodic inspections happen, based on expected rope life on that crane, how harsh the environment is, the share of lifts at maximum rating, and shock loading. Intervals can be uneven, but there must be at least one per month, logged in the operator's crane log. 6.5.1.3.1
Periodic (who and how much rope). A competent person carries out periodic inspections and covers the rope length in use at the crane's current height. 6.5.1.3.2
Annual. After 12 months in service, the crane gets an inspection that includes all fixed ropes and all running ropes checked under the periodic inspection clause, plus all load-carrying gear such as sheaves and blocks. 6.4.7 b), c), d)
Special inspections. Special inspections are the ones done after a shock load, contact with electricity, any other incident, a repair or alteration, or a long shutdown. Once the need for one is identified, an engineer provides the inspection procedure, and an engineer verifies the special inspection. 6.4.8 (Note) and 6.4.8.1
After prolonged shutdown or severe weather. Before work restarts after a long shutdown or conditions such as severe weather, an engineer competent in tower crane inspection carries out an inspection to the annual inspection clause (which covers fixed and running ropes), along with a soil inspection. 6.4.8.4
Idle ropes. Rope that has not been in regular use for over a month, because the crane was shut down or stored, gets a periodic inspection before it goes back into service. 6.5.1.3.5
After incidents or reassembly. Inspect the rope whenever an incident may have damaged it or its termination, and every time a rope is put back to work after the crane is dismantled and reassembled. 6.5.1.3.5 (second paragraph)
Who inspects. A designated person carries out all rope inspections. A competent person reviews any rope defect found and decides whether it means the rope must come off right away. 6.5.1.1
Sheaves at rope change. Check sheaves for general or uneven wear, grooving and flat spots before a new wire rope is installed, and any time the rope shows early wear or damaged or broken wires. 6.5.4.1
Record keeping: rope condition report. Keep a dated rope condition report on file that refers to the damage types listed for periodic inspection. 6.5.1.3.7
Record keeping: long-term program. The standard recommends a long-term inspection program that records the examination of ropes taken out of service, so visual findings can be related to the rope's real internal condition. 6.5.2.1
Record keeping: crane logs. The owner's crane log must hold the rope installation date. The operator's crane log must record every inspection with its date, who did it and total machine hours, plus the name of whoever installed the rope and when. 6.2.2 e); 6.2.3 c), e)
Record keeping: wire rope report. Each rope on the crane needs a wire rope report kept with the crane log. At minimum it gives diameter, length, wire tensile strength and finish, construction and lay, number of outer strands, core type, rated minimum breaking force, recommended working load limit, end fitting and proof test loads, whether a swivel is allowed, the rope maker or supplier, and who issued the report. 6.5.2.4
Inspection criteria
Distortion. Look for any distortion of the rope, such as kinks, crushing, unstranding, birdcaging, strand displacement, waviness or core protrusion. 6.5.1.2.2 a)
Diameter change. Look for spots where the rope diameter has locally shrunk or grown. 6.5.1.2.2 b)
Corrosion. Look for general corrosion of the rope. 6.5.1.2.2 c)
Broken or cut strands. Look for strands that are broken or cut. 6.5.1.2.2 d)
Broken wires. Note how many wires are broken, where they are and what type of break they are, then use the rope replacement clause 6.5.2.2 for guidance. 6.5.1.2.2 e)
Wear. Look for wear on the rope. 6.5.1.2.2 f)
Heat and arcing. Look for damage from heat or electric arcing. 6.5.1.2.2 g)
Drum hot spots. On drums, pay close attention to flange points, crossover points and spots where the rope is picked up over and over, checking for the damage types in the daily list. 6.5.1.2.3
Rotation-resistant rope. Rotation-resistant rope needs close inspection. It is easily damaged by handling and misuse, wears faster on small sheaves or reverse bends, and can fail from the inside out where damage may not be visible. 6.5.1.2.3 (Note)
Limited-travel sections. Check rope that rests on saddles or equalizer sheaves, or on any sheave where rope movement is limited. 6.5.1.3.3 a)
Near end fittings. Check rope at and close to end fittings, since broken or corroded wires can poke out there. 6.5.1.3.3 b)
Reverse bends. Check rope sections that bend one way and then the other. 6.5.1.3.3 c)
Hidden sections. Check rope that is normally out of sight in routine visual checks, such as lengths passing over sheaves. 6.5.1.3.3 d)
Reduction in rope diameter (periodic). In periodic inspections, look for a reduction of rope diameter caused by the core no longer supporting the strands, corrosion inside or outside the rope, or worn outside wires. Reduced diameter tends to show as a longer lay and local thinning. The removal limit for a decrease in rope diameter from wear is in 6.5.2.2 e). 6.5.1.3.4 b) and Note
Reduction in rope diameter, rotation-resistant rope. Any loss of diameter on rotation-resistant rope may mean the core has failed. A competent person must check that section immediately and decide whether the rope comes out of service. 6.5.1.3.4 c)
End connections. Look for broken wires, or wires with heavy corrosion, at end connections. 6.5.1.3.4 d)
End fittings. Look for end fittings that are badly corroded, cracked, bent or worn, and for end connections such as wedge sockets that were fitted wrongly. 6.5.1.3.4 e)
How to judge wear. Wear is best judged by comparing an unused length of the rope, for example on the drum, with how a used length looks. 6.5.2.2 e)
How to measure waviness. Waviness is checked by laying a straightedge along the rope and measuring the gap between it and the underside of the rope helix, compared against the nominal rope diameter. Figure 1
Counting broken wires. Per the notes to Tables 1 and 2, a broken wire has two ends but counts as one break. Filler wires are not treated as load-bearing, so they are left out when counting the load-bearing wires in the outer strands, which sets the table row to use. Tables 1 and 2, notes a) and b)
Wedge socket dead end. Check the rope regularly where it leaves a wedge socket on the dead-end side. Fast spinning of the rope during loading and unloading can make it flip-flop, fatigue and break. Figure 2 (Warning)
Wedge socket tail. For the method with a short rope piece clipped to the dead end, the tail T is at least 6 rope diameters and not under 150 mm (6 in), and distance S should be about 3 rope diameters or 75 mm (3 in), whichever is less. Figure 2 also shows the extended wedge method and the dual (double) saddle clip method. Figure 2 a) to c)
Terminations allowed. End fittings must be the type and size set by the crane or rope maker or a competent person. Loop back and Flemish eye splices must be mechanical splices with a thimble, made the way the rope or fitting maker says. Hand-spliced ends are not allowed. 4.11.2 a) to d)
Wedge sockets and swaged fittings. Fit wedge sockets as the maker specifies using a method from Figure 2, and fit swaged fittings as the rope or fitting maker recommends. 4.11.2 e), f)
Proof testing terminations. After fitting, swaged and poured (spelter) sockets and all loop back eye ends are proof tested as the rope or fitting maker recommends, capped at 50% of the rope's minimum rated (or nominal) breaking strength. 4.11.2 g)
Wire rope clips. Clips must never be the only termination on crane rope. Where used with wedge sockets, clips go on the unloaded dead end only. 4.11.2 h)
Swivels. Active inline swivels may be used with ASTM A1023/A1023M Category 1 rotation-resistant rope. On Category 2 or 3 rotation-resistant rope, or on regular rope, a swivel needs approval from the crane maker, rope maker or a competent person. 4.11.2 i)
Design factors. Minimum design factors: 5 for load hoist and trolley ropes, 3.5 for boom hoist ropes, and 3 for pendants, guy ropes and stay ropes. The factor is the combined minimum breaking force of every supporting rope divided by the static load on them at maximum load. 4.11.1 a), b), c), e)
Fibre core and rotation-resistant limits. Fibre core rope must not be used for pendants, stay ropes or guy ropes. Rotation-resistant rope is not allowed in boom hoist reeving unless the crane maker specifies it, or as a pendant, and it must have 15 or more outer strands (ASTM A1023/A1023M Category 1) or a plastic coated inner core. 4.11.1 c), d), f)
Multi-part reeving and temperature. Where several rope parts share a load, their tensions must be equalized. Where the rope is exposed to ambient temperatures above 82 C (180 F) or below -40 C (-40 F), consult the rope maker before use. 4.11.1 g), h)
Sheave grooves (design). Sheave grooves must be free of surface defects that could harm the rope and must cradle the rope closely. For a new sheave, the groove radius should be 6% to 10% larger than the nominal rope diameter. Groove sides flare outward and flange rims must run true. 4.12 a)
Rope retention and sheave bearings (design). Running ropes must be kept in their sheave grooves under all conditions, and sheave bearings need a way to be lubricated unless sealed for life. 4.12 b), c)
Sheave size and material (design). Upper and lower load block sheaves need a pitch diameter of at least 18 times the nominal rope diameter, and boom hoist sheaves at least 15 times. Aluminum sheaves are not allowed. 4.12 d), e)
Minimum wraps on drum. The maker sets how many full wraps must stay on the drum with the hook at its lowest working point, or on the boom hoist drum at the lowest allowed boom angle. It must never be under three wraps, or the drum maker's figure. 4.13.1
Drum attachment, flanges and spooling (design). Attach the rope's drum end as the crane maker specifies. Grooved drum flanges must stand at least one rope diameter or 25 mm (1 in) above the top layer, whichever is more; ungrooved drum flanges at least 2 rope diameters or 65 mm (2-1/2 in). The rope must spool evenly. 4.13.2 to 4.13.5
Drum diameter (design). The drum must be large enough that the first rope layer has a pitch diameter of at least 18 times the nominal rope diameter. 4.13.6
Sheave grooves (inspection). Measure sheave grooves to confirm their shape is still inside the maker's limits. 6.5.4.2 a)
Sheave flanges (inspection). Inspect sheave flanges for cracks, chips, breaks, deformation or any other damage. 6.5.4.2 b)
Sheave bearings (inspection). Check that sheave bearings turn freely without too much play. 6.5.4.2 c)
Lubrication and inspectability. Keep rope well lubricated with a lubricant that does not block visual inspection, and give extra attention to lengths over sheaves or otherwise hidden. Lubrication reduces internal friction and slows corrosion. 6.5.3.5
Replacement rope. A replacement rope and its connections must be rated at least as strong as the originals supplied by the maker. Any change to the original grade, size or construction must be specified by a rope maker, the crane maker or a competent person. 6.5.2.3
Handling and installation. Store rope to limit damage, unreel it as the rope maker recommends without kinking or adding twist, seize both sides before cutting (especially rotation-resistant rope), and avoid dragging it through dirt or over objects that could scrape, nick, crush or sharply bend it. 6.5.3.1 to 6.5.3.4
Removal (discard) criteria
Decision process. When any rope removal criterion is reached, a competent person inspects the affected section and decides whether the rope must come off immediately or may run until the end of that work shift. 6.5.2.1 (also 6.5.1.2.1, 6.5.1.2.4, 6.5.1.3.2)
No exact retirement rule. The standard says there is no precise rule for exactly when to replace a rope. 6.5.2.1
Periodic findings. If periodic inspection finds the listed damage, the rope is assessed under the replacement clause and removed once it meets the replacement criteria. 6.5.1.3.6
Randomly distributed broken wires. For breaks scattered along rope that runs over steel sheaves and on and off a single-layer drum, or at crossover zones on multi-layer drums, Table 1 (regular rope) and Table 2 (rotation-resistant rope) give the number of visible broken wires that, once reached or exceeded, calls for removal. The limit depends on the number of load-bearing wires in the outer strands, the lay (regular or Lang, for Table 1), and whether the section works on sheaves and a single-layer drum or spools on a multi-layer drum, over two reference lengths given in rope diameters. 6.5.2.2 a); Table 1 (round strand ropes); Table 2 (rotation-resistant ropes, ASTM A1023 Category I and II)Limit set by the standard's table: check your rope in the calculator
Table adjustments. Notes to Tables 1 and 2 shift some Seale constructions to a different row, limit the multi-layer drum figures to crossover and wrap interference damage, and allow a higher count for mechanisms with a known ISO classification in a set range. The tables credit ISO 4309 as their source. Tables 1 and 2, notesLimit set by the standard's table: check your rope in the calculator
Grouped broken wires. Where breaks cluster in one or two neighbouring strands on rope that does not spool on the drum, the rope may need to be discarded even when the count is under the table figure for a length of 6 rope diameters. 6.5.2.2 b); Tables 1 and 2Limit set by the standard's table: check your rope in the calculator
Breaks at core contact. Replace the rope if two outer wires are broken where they touch the rope core, shown by a wire or loop of loose wires sticking out. 6.5.2.2 c)
Breaks at end termination. Replace the rope if two or more broken wires can be seen at an end termination fitting. 6.5.2.2 d)
Outer wire wear. Replace the rope when the outside wires have lost a third of their original diameter to wear. 6.5.2.2 e)
Decrease in rope diameter from wear. Replace the rope when wear has cut its diameter by 5% or more compared with the actual rope diameter. 6.5.2.2 e)
Reduction in rope diameter, rotation-resistant rope. On rotation-resistant rope, a 5% reduction in rope diameter signals core failure and the rope must be removed at once. 6.5.2.2 f)
Distortion. Replace the rope for waviness, strands or wires pushed out of the rope, kinks or tightened loops, birdcaging, crushing, bends, or any other damage that distorts the rope structure. 6.5.2.2 g)
Waviness on straight sections. On a straight length that never passes over a sheave or onto the drum, discard the rope if the straightedge gap under the helix reaches one third of the nominal rope diameter. Figure 1 a)
Waviness on running sections. On a length that passes through a sheave or spools onto the drum, discard the rope if the straightedge gap under the helix reaches one tenth of the nominal rope diameter. Figure 1 b)
Heat damage. Replace the rope if there is any sign of heat damage, whatever the cause. 6.5.2.2 h)
Power line contact. Replace the rope after any contact with high-voltage lines, including through rigging or the load, that could send current through the rope. 6.5.2.2 i)
Non-steel sheaves. On synthetic or synthetic-lined sheaves, many wires can break inside before anything shows on the outside, so the table limits do not apply. Ask a competent person, together with the maker of the sheave, drum or crane, for the removal criteria. 6.5.2.2 (introduction); Tables 1 and 2Limit set by the standard's table: check your rope in the calculator
Cutting off a worn end. If one well-defined area wears faster than the rest, cutting a length off the worn end to move the wear point can extend rope life, provided the diameter at the worn part is still adequate and the maker's recommendation is followed. 6.5.3.6
Wedge socket damage. Rope that a wedge socket has damaged, for example with kinks, bends, crushing or loosened outer strands, may be shortened to remove the damaged length, taking special care when cutting. 6.5.3.7
Sheave removal. Take a sheave out of service if a flange is broken or bent, or if a crack is found anywhere in it. A replacement sheave must match the old one's hardness, or be at least Rockwell C 35 if that hardness is unknown. 6.5.4.4
Sheave repair. A sheave with groove damage or wear may be reconditioned only with the sheave maker's approval. 6.5.4.3
Hazards found in inspection. Any hazard found during Clause 6 inspections must be fixed before the crane goes back to work. 7.4 a)
Terms used
Competent person. Someone qualified through training or real experience with the type of tower crane in question, who knows the relevant standards and safety rules and can spot errors and hazards. 3
Designated person. Someone the employer or its representative has picked as competent to do particular tasks. 3
Crossover point. The spot on a drum where one rope layer crosses over the layer beneath it. 3
Flange point. Where the rope meets the drum flange as it moves up to the next layer. 3
Rotation-resistant rope. Wire rope with an inner strand layer laid one way and an outer layer laid the other way, which offsets torque so the rope is less inclined to spin. 3
Category 1 rotation-resistant rope. The standard ties ASTM A1023/A1023M Category 1 to rope with 15 or more outer strands. 4.11.1 d) ii)
Guy rope. A fixed-length support rope that holds two attachment points at a roughly constant distance. Also called a stay rope, standing rope or pendant. 3
Equalizer. A device that makes up for rope parts of unequal length or stretch. 3
Pitch diameter. The diameter of a sheave or drum measured to the centre line of the rope. 3
Sheave. A grooved wheel sized for a given wire rope that redirects a running rope. 3
Drum. The cylinder the rope winds onto to raise or lower a load. 3
Load hoist. The hoist drum plus the rope reeving that raises and lowers loads. 3
This page summarises CSA Z248:17 in our own words for general information. It is not
a copy of the standard, does not reproduce its tables and does not replace it. Clause numbers refer to
CSA Z248:17 (December 2017). The full standard is available from CSA Group. The rope or crane manufacturer's criteria take
precedence where they are stricter, and inspection and discard decisions remain those of your competent
or qualified person.
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