By Dean McDonald, founder, Crane Rope Solutions
Frequently asked questions
Is there an accredited wire rope inspection course in Canada?
No. There is no CSA- or WorkSafeBC-accredited rope inspection course, and no ASME or ISO accreditation either. The standards require inspections by a competent person. Get training from a rope maker and from the crane maker, because the crane OEM can override local standards in some cases, so inspectors need to know the specific crane.
Which standard covers crane rope inspection in Canada?
CSA Z150 for mobile cranes sets out the daily, periodic and annual inspection requirements. Many fleets also use ISO 4309 for discard criteria. We can build a crane-specific inspection template that covers every rope, its discard criteria and the minimum groove size of every sheave.
What's the difference between a broken wire and a broken strand?
A broken wire is one wire. A broken strand is a whole strand of wires, and it means immediate discard. Inspection reports have to use the right word.
Can I use a right-hand lay rope where the OEM specifies left-hand?
Not without care. On a multi-layer drum, lay direction matters less once the first layer is tensioned. But the opposite lay can cause problems in the reeving and damage the first drum layer. We don’t recommend it unless the owner is prepared to trial it and watch how it spools.
How often should crane pendant ropes be inspected?
Under ISO 4309, pendants fall under periodic inspection, with the frequency set by how hard the crane works. In normal use we have customers recertify pendants every year and keep them on their sling and rigging inventory so they aren’t forgotten.
Should a tower crane use one hoist rope for the whole building project?
We recommend two hoist rope lengths. Start with a shorter rope through excavation and shoring, then switch to the longer rope at around half the final height, before climbing to full height. Less rope on the drum spools better and lasts longer.
How many broken wires are allowed on a multi-layer drum?
It depends on the rope’s RCN. For example, for an RCN 09 rope in sections spooling on a multi-layer drum, ISO 4309 allows 18 visible broken outer wires over 6d and 36 over 30d.
When is a crushed rope on a multi-layer drum a discard?
Some crane makers publish their own crushing tolerance. Liebherr gives a formula for distortion severity in its operating manuals, and confirmed that the same criteria apply to the LR 1600/2 and LG 1750. Check your crane’s manual first.
Does a decrease in diameter count when the rope runs on synthetic sheaves?
Under ISO 4309, a uniform decrease in diameter is a discard criterion for rope that runs through steel sheaves or spools on a single-layer drum. It isn’t used for sections on multi-layer drums. Check with the rope maker for synthetic sheave systems.
What should I check before installing a replacement hoist rope?
The OEM part number or rope specification, the minimum breaking load on the certificate (often a bigger concern than tolerance), the end fitting dimensions, and the sheave grooves. A new rope will likely be a bit larger than the old one.
What do I need to order a replacement sheave?
The rope size, the D (rim) dimension, the groove depth (on a worn sheave this has to be calculated from the rope size, because it can’t be measured), the through-bore and bearing number, and whether it is webbed or solid. For new bearings you also need the shaft diameter and the rpm of the fastest sheave.
What groove size should a sheave have?
Groove the sheave to the rope’s actual diameter plus about 1% clearance. Rope makers typically give 5% to 10% over nominal, and sheave makers often cut grooves 6% to 8% over nominal.
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