Rope Category Number is used in connection with steel wire rope
Rope Category Number is used to determines when a wire with an outer wire break must be discarded or not.
According to the standard NF ISO 4309:2017, the Rope Category Number categorises steel wire rope by the number of load-bearing wires obtained by multiplying the number of outer strands with the number of wires constituting them.
An example:
6x36 wire rope refers to a number of wires carrying of: 6x36 = 216 or an RCN of 09.
35x7 non rotating wire rope (16 outer strands and 7 wires constituting them): 16x7=112 or an RCN of 23-2.
What is the purpose of the Rope Category Number?
It is used to determine the maximum number of broken wires, when reached, should lead to the removal of the wire rope.
The maximum number of broken wires before a rope becomes dangerous depends on the construction of the wire rope.
To obtain the RCN classification, the number of load bearing wires will then be cross-referenced with the tables below using either the table of parallel-closed ropes or the table of rotation-resistant ropes depending on the type of wire rope.
Where do I find the RCN of a steel wire rope?
There are more ways to find the RCN of a wire rope:
- On the data sheet from the supplier
- By using the data in the tables below from the NF ISO 4309v2017 standard (refer to the standard to use these tables)
Single-layer or parallel-closed steel wire rope - Number of wire breaks, reached or exceeded, of visible broken wires occurring in single-layer and parallel-closed ropes, signaling discard of rope (acc. to ISO 4309:2017)
| RCN - Rope Category Number | Total number of load-bearing wires in the outer layer of strands in the rope n |
|---|---|
| 01 | n ≤ 50 |
| 02 | 51 ≤ n ≤ 75 |
| 03 | 76≤ n ≤ 100 |
| 04 | 101 ≤ n ≤ 120 |
| 05 | 121 ≤ n ≤ 140 |
| 06 | 141 ≤ n ≤ 160 |
| 07 | 161 ≤ n ≤ 180 |
| 08 | 181 ≤ n ≤ 200 |
| 09 | 201 ≤ n ≤ 220 |
| 10 | 221 ≤ n ≤ 240 |
| 11 | 241 ≤ n ≤ 260 |
Rotation-resistant steel wire ropes - Number of wire breaks, reached or exceeded, of visible broken wires occurring in rotation-resistant ropes, signalling discard of rope (acc. to ISO 4309:2017)
| RCN - Rope Category Number | Total number of load-bearing wires in the outer strand layer of the rope n |
| 21 | 4 strands : n ≤ 100 |
| 22 | 3 or 4 strands : n ≤ 100 |
| At least 11 outer strands | |
| 23-1 | 71≤ n ≤ 100 |
| 23-2 | 101 ≤ n ≤ 120 |
| 23-3 | 121 ≤ n ≤ 140 |
| 24 | 141 ≤ n ≤ 160 |
| 25 | 161 ≤ n ≤ 180 |
| 26 | 181 ≤ n ≤ 200 |
| 27 | 201 ≤ n ≤ 220 |
| 28 | 221 ≤ n ≤ 240 |
| 29 | 241 ≤ n ≤ 260 |
| 30 | 261 ≤ n ≤ 280 |
| 31 | 281 ≤ n ≤ 300 |
| n > 300 |
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