HSE: Industrial rope access - investigation into items of personal ...

The results over the rounded concrete coping, however, were very different. After
approximately 600 cycles, taking 2 hours, only slight sheath damage was seen. The rope slowly
polished the concrete and abrasion only occurred because of a small bubble imperfection in the
edge.
This was particularly surprising because in some subsequent tests, with an edge-protector in
place, far worse damage was seen over this same edge. The only conclusion that could be drawn
was that the protectors themselves were causing the damage!
5.4 ROLL MODULE (PETZL)
This device consists of a series of “U” shaped roller cages linked by screw link connectors
(maillon rapides).
Within the cages, the rope is prevented from touching the abrasive surface by aluminium rollers,
with side rollers to prevent lateral movement. By linking the appropriate number of cages
together, any variety of abrasive edge can be traversed safely by the rope. (Just two cages in the
case of a right-angled edge, more for gradual edges.)
Although the test was performed on all three of the edges, the edge material is largely irrelevant,
as the rope does not touch it. In the tests, the only effects on the rope were flattening and black
marks from the aluminium rollers. The longest test was run for two hours, a total of 600 cycles.
This result may be taken as representative of the use of any type of smooth rollers – the only
difference may be in practicability of use, not in the (total) degree of protection given.
5.5 CANVAS SHEATH
A rectangular double-thickness strip of 15 oz. natural shrunk canvas, secured as a tube by means
of velcro strips, fixed around the rope.
Compared to other types of fabric protectors performance was impressive, taking 270 cycles (54
minutes) over the steel edge to wear through both the protector and the rope sheath. Over the
sharp concrete edge only slight wear was seen after 450 cycles (90 minutes).
5.6 POLYVINYL CHLORIDE (PVC) COATED FABRIC SHEATH
Identical in construction to the canvas rope protector, except that it was made out of a PVC
coated polyester fabric (6 oz. CAFLEX FP600FREN71).
Performance, however, was nowhere near as good as plain canvas, with severe rope damage
occurring after only 75 cycles on the steel edge.
It fared little better on the sharp concrete edge, wearing through after 75 cycles, with sheath
failure occurring after 100 cycles.
Over the rounded concrete edge the protector did not wear through, but the PVC coating rubbed
off, leaving stains on the rope and increasing friction and hence heat. Damage then occurred due
to melting rather than abrasion. After 300 cycles, the protector was not in a reusable state and
the rope was both stained and glazed.
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