What Does Rope Category Number (RCN) Mean?
Rope Category Number is used for steel wire rope
Rope Category Number (RCN) is used to help determine whether a steel wire rope with visible external wire breaks should be discarded.
According to ISO 4309:2017 (AS 2759), the Rope Category Number classifies steel wire ropes based on the number of load-bearing wires. This is determined by multiplying the number of outer strands by the number of wires within those strands.
Examples:
A 6 × 36 steel wire rope has:
6 × 36 = 216 load-bearing wires, corresponding to RCN 09.
A 35 × 7 rotation-resistant steel wire rope, with 16 outer strands containing 7 wires each, has:
16 × 7 = 112 load-bearing wires, corresponding to RCN 23-2.
What is the purpose of the Rope Category Number?
RCN is used to determine the maximum allowable number of broken wires before a steel wire rope should be discarded.
The number of broken wires that can occur before a rope becomes unsafe depends on the rope's construction.
To determine the appropriate RCN classification, the number of load-bearing wires is cross-referenced against the relevant ISO 4309 tables. Different tables are used depending on whether the rope is a single-layer or parallel-closed rope, or a rotation-resistant/rotation-free rope.
Where can I find the RCN for a steel wire rope?
There are several ways to determine the RCN:
- Check the manufacturer or supplier's data sheet.
- Refer to the relevant tables in ISO 4309:2017 (AS 2759). The standard should be consulted for the correct application and interpretation of these tables.
Single-layer and parallel-closed ropes
The following RCN categories are based on the total number of load-bearing wires in the outer layer of strands:
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