From the ORC regulations:
3.14.6 Lifeline minimum diameters, required materials,
specifications
a) Lifelines shall be stranded stainless steel wire of minimum
diameter in table 8 below. Lifelines installed from 1/99 shall be
uncoated and used without close-fitting sleeving.
**
Notwithstanding 3.14.6 (a) above, temporary sleeving may be
fitted provided it is regularly removed for inspection
**
b) Grade 316 stainless wire is recommended. **
