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The hoisting cable: carrying a heavy load
A multi-ton load hanging from a lowly cable! Impressive! Although this technique may seem basic and simple, the lifting cable is more than just a simple steel wire that can carry a load. It consists of individual steel wires wrapped around a second rope (called the core) that "work" by fitting together. In the case of a wire rope hoist, it is the result of the overall engineering of a lifting system and its essential components, of which it is a part. This type of rope is therefore carefully selected by the manufacturer for the particular and specific application of the hoist. In addition, it is tested against high safety criteria and factors to ensure its strength.
But in its everyday usage, we rarely stop to think about this essential component of industrial lifting and handling... except when that rope has shortcomings. When it does, everyone's safety suddenly seems to be hanging by a thread! It is therefore logical not to take the usage, inspection and replacement of wire rope dedicated to industrial lifting lightly.
So how do you know when a wire rope needs to be replaced? And what do you do if you have any doubts about the condition of a wire rope?
How can you tell if a hoisting cable is still in good condition?
As mentioned above, the hoisting cable has been carefully selected by the hoist designer. The hoist designer therefore includes a series of replacement criteria in his maintenance guide. Consequently, to know if a hoisting cable is still good, it is best to take into account the recommendations of the cable hoist manufacturer. But the cable manufacturer itself can also be an excellent source of information.
Given the elements mentioned above, it is always preferable to replace a wire rope with the original one, i.e., the wire cable chosen by the manufacturer at the design stage. That being said, it is important to note that it is not uncommon to find hoists equipped with an equivalent replacement cable in factories. In these cases, the CSA B167-16 and ISO 4309 standards, specific to lifting equipment, are the references for evaluating the condition of a cable. These documents provide guidelines for determining if a wire cable should be removed from service. The attached table details the list. For example, the presence of rust, deformation, broken wires, etc. are all elements that may indicate that the rope is non-compliant and therefore should be replaced. But when is it appropriate to act, and how?
Criteria for removing a wire rope according to CSA B167-16, appendix G.1.4
- Three or more broken wires in a strand along the length of a cable pitch;
- Six or more broken wires randomly distributed over the length of a cable pitch;
- A broken wire near a ferrule (i.e., clevis, solder, or taper socket);
- A wire in the hollow of the cable, if determined to be part of the core;
- Visual evidence of hulling, crushing, basket or cage deformation, hammering, curling, twisting, warping, corrosion, heat damage, web protrusion or loss of diameter.
Figure 1 - Basket strain - ISO 4309 standard
Figure 2 - Shell - ISO 4309 standard
When in doubt, act... the appropriate way!
The process is simple: at the slightest visible defect on a cable, a red flag must be raised. In industrial handling and lifting, no risk should be taken, because the safety of everyone is at stake. A simple rule to avoid the worst: when in doubt, take action! But not just any way! In a field where safety is the main concern, you must take the proper step: call on a lifting systems specialist! Why?
First and foremost, the role of a specialist is to use his or her experience and knowledge of the field to assess the situation in no uncertain terms. A true specialist will have all the reference documents to rely on or know where to find the necessary information. He will be able to tell you if the cable needs to be removed. If so, he will probably have helped you avoid a potentially serious incident. If not, he will be able to reassure you and avoid the unnecessary replacement of a costly part, while telling you what to look for during your crane inspections.
Furthermore, while it is true that the checking the conformity of a cable should be done by an expert, the same is true for its replacement. Only a technician with the required experience and training should perform the replacement (CSA B167-16 standard, section 8.2). This will ensure that the installation and break-in are carried out according to the rules of the trade. It should also be noted that a hoist with a non-compliant cable must be shut down until the new cable has been installed and tested on the hoisting equipment.
In conclusion, the hoisting cable is more than just a tool. It is a valuable and indispensable machine, a lifting device component carrying heavy loads. But the responsibilities it carries with it are just as heavy: to ensure the employees’ safety. For this reason, being on the lookout and reacting to the slightest doubt also constitutes a safety measure. In addition, it is advisable to leave the inspection and replacement of a cable in expert hands. Groupe Industriel Premium's experienced specialists will be happy to take care of it!
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