We seem to be weighed down by paper these days, but legislation requires us to keep certain documents - it’s not just red tape! This article deals with the importance of the wire rope test certificate. Later posts will deal with maintaining records of your regular inspections and examinations.
An example wire rope test certificate. Actual test certificates may vary in content and appearance.
The test certificate is vital to ensure that you fit the correct rope to your crane. The key elements are:
There is a massive difference in breaking loads for the same rope diameter. Wire rope construction, the tensile strength of the wires, the type of core, and whether the rope is compacted or not will make a huge difference in breaking load values.
The following table details a range of values for 16mm ropes:
|Construction||Tensile (N/mm²)||Core Type||Rope Type||Breaking Load (t)|
|6xK36WS||1960||IWRC(K)||Single Layer Compacted||22.0|
|6xK36WS||2160||IWRC(K)||Single Layer Compacted||23.9|
|8xK19S||1960||EPIWRC(K)||Single Layer Compacted||23.0|
|8xK26WS||2160||EPPWRC(K)||Parallel Lay Compacted||27.18|
Installing the incorrect rope type will, at best, dramatically reduce rope life, and at worst, could result in a rope failure. For example, installing a non-rotation resistant rope when a rotation resistant rope is required will lead to instability of the load and damage to the rope. The reduction of diameter discard criteria with regards to ISO 4309 may also be different.
From a paperwork perspective, this is not especially important as lay types are easily identifiable. However, in terms of inspecting wire rope, it is a critical piece of information as it impacts the discard criteria for broken wires.
The core type is not always apparent from visual inspection. The core type is important when determining the maximum diameter reduction allowed by ISO 4309.
The rope diameter must correctly match the machine to which it is fitted. Rope diameter will have been matched to the drum diameter, sheave diameter and sheave groove diameter by the crane manufacturer.
Tensile. Knowing what the original tensile is versus that of the to be installed rope is critical to ensure the compatibility with the sheave and drum material. If the rope tensile is too high, premature sheave and drum wear are likely.
Thanks for reading this far! We have detailed the important elements on a test certificate. This will aid inspection and is critical to determine that the rope is strong enough for the application. The correct use of discard criteria detailed in the ISO 4309:2017 tables is only possible if you know the information contained on the rope certificate.
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