rope age

[nickwilliams]

I'll get me coat....

 

[gus horsley]

And of course the life of a rope depends on where it is stored.  When I was a climbing instructor I was horrified to visit a centre where the ropes were stored in a shed which had paint and thinners in it, some of it in open containers.  I know it doesn't apply so much to SRT ropes but if you close you eyes and run a finger and thumb down climbing ropes you can feel where they have stretched due to falls.

 

[vanoord]

For what it's worth... I bought a short climbing rope yesterday and in the accompanying paperwork, it has a section entitled "Identifying the age of the rope by the control thread", which says:

A control thread in the ropes core identifies the year of manufacture.
1999 green/yellow
2000 black/yellow
2001 red/blue
2002 red/green
2003 red/black
2004 green
2005 blue
2006 yellow
2007 black
2008 red/yellow
2009 blue/yellow

I shall accept that this is a climbing rope and that a static rope *might* use a different system, but I wouldn't be at all surprised if this were not some form of industry standard.

 

[paul]

It looks like this may vary from manufacturer to manufacturer:

See http://www.spelean.com.au/BW/BWindicator.html

 

[Bob Mehew]

BS EN 892:1996 which covers climbing ropes does not require a marked tape within the rope as is required for SRT ropes by their standard.  I guess that this may well be due to the problem that the tape in SRT ropes gets rubbed with use and the characters become difficult to read.  The higher elongation (stretchability) of dynamic rope presumably would soon make a tape useless. If indeed one could get a tape to simply cope with the stretch of greater than 8% v 5% for SRT ropes.

 

[Downer]

This is wierd. All the books and good advice pages say a rope should be retired when it's 5 years / 2 years / 3 minutes old and they all tell us to avoid storing them in sunlight. Yet Pit Schubert is adamant the strength loss is negligible even on very old NYLON ropes ~30 years unless the rope is exposed to a strong acid, even with rope regularly exposed to full strength sunlight. He reckons the only thing that ever breaks a rope is heavy loading over a sharp edge. Either he's an irresponsible liar or all the writers are just repeating each other's folk-myths...

I believe at least one caving club has tested the assertion that "all ropes degrade when exposed to ultraviolet" and found it to be plain untrue, though I can't find the reference. So, has anyone actual practical experience of NYLON (or polyester but NOT polypropylene!) ropes breaking under test when they have definitely not been mechanically or chemically abused but have merely been stored or used lightly - with and without exposure to sunlight for comparison purposes?

 

 

[cap n chris]

As an aside (and sadly not within the definitions you're asking for!) it is worth stating that Bob tested a rope for me some years back at Hidden Earth (at Churchill School, nearby) - for which many thanks! - and IIRC my rope at that time was about 4 years old and had been used for general caving (getting nowhere near the amount of use my present ropes do!); it broke at the knot after a single drop test and was retired the same day. For this reason I'm now on a 2 year retirement cycle for my ropes!

 

[Downer]

As an aside (and sadly not within the definitions you're asking for!) it is worth stating that Bob tested a rope for me some years back at Hidden Earth (at Churchill School, nearby) - for which many thanks! - and IIRC my rope at that time was about 4 years old and had been used for general caving (getting nowhere near the amount of use my present ropes do!); it broke at the knot after a single drop test and was retired the same day. For this reason I'm now on a 2 year retirement cycle for my ropes!

Was that static rope on FF2?

 

[cap n chris]

"Yarp".

 

[Downer]

"Yarp".

The reason I asked is because static rope is not good at absorbing energy and FF2 is a huge shock. In fact, according to Dave Elliot " [scenario] equates to a fall factor 2 - a very high factor which would almost certainly break the rope, or the belay, and definitely break the caver!" Likewise, Andy Sparrow's description of the "standard" test is 80kG at FF1, not FF2. You may find a new sample of that rope straight off the reel would have failed. I'm just guessing though.

 

[Downer]

Sorry - finger problems and there's no delete button - hint!

 

[MSD]

It seems to me that this kind of discussion needs to be put into a context of empirical data. How often do caving ropes break whilst in use (as opposed to FF2 drop tests)? In what circumstances? Since the way SRT ropes are handled and used obviously varies enormously from rope to rope, theoretical specifications and laboratory testing should be validated against use in the field.

Mark

 

[Cave_Troll]

"how often do ropes break?"

A not very often. BUT the consequences when they do break are huge, hence why many people choose to err on the conservative side.

 

[Downer]

"how often do ropes break?"

A not very often. BUT the consequences when they do break are huge, hence why many people choose to err on the conservative side.

Is that "not very often" as in "occasionally" or "not very often" as in "never, except when stressed in ways that we are not discussing here"?

I'm not sure that acting on the results of tests under enormous shock loads is actually conservative. Suppose that Schubert is correct and, to simplify a bit, ropes do not weaken enough to break except when run over sharp edges. Worrying whether a rope survives two or only one FF1 tests is academic. You shouldn't be rigging so close to the rope's limit in the first place, let alone that of the poor sod falling on it. But why change a rope if a moderate loss of strength is a normal and safe part of "running it in" over ten or twenty years? 

But I really didn't want to get bogged down in rope testing, I just wanted to know any actual facts to support or refute the idea that mere passage of time or the action of sunlight are enough to make a rope dangerous.

 

[Cave_Troll]

rope , IIRC, is nylon.
I have seen nylon sheet and a rucksack that have spent so much time in the sun. this fabric was very weak , and in one case, just picking the rucksack up "not by the straps" was enough to rip the fabric.

so i have some evidence to say that lots of UV light does affect nylon.

 

[Downer]

rope , IIRC, is nylon.
I have seen nylon sheet and a rucksack that have spent so much time in the sun. this fabric was very weak , and in one case, just picking the rucksack up "not by the straps" was enough to rip the fabric.

so i have some evidence to say that lots of UV light does affect nylon.

Fair enough. That would represent more than 90% loss of strength.

 

[cap n chris]

the action of sunlight are enough to make a rope dangerous.

Ah, yes, sunlight; that oft-overlooked underground hazard! 

BTW, have checked; it was FF1, not 2.

 

[Cave_Troll]

granted most caving applications won't involve a significant amount of UV

Insitu traverse lines to open pots.
"training" ropes on the outside of the club hut / up a tree
left in a coil beside the club hut

 

[Downer]

the action of sunlight are enough to make a rope dangerous.

Ah, yes, sunlight; that oft-overlooked underground hazard! 

BTW, have checked; it was FF1, not 2.

FF1, yes, I thought you might come back with that!

Granted that prolonged sunlight was rare underground, at least until the Scurion, but what about storage? The intensity in a shed might easily be 10% of that in the open, especially in the near-UV region which isn't blocked by window glass. In which case after five years it would have had equivalent to being outside for six months. [Checks arithmetic, twice.]

As to whether it affects the strength significantly, I'm pretty sure the advice to protect ropes from sunlight wasn't based on Cave troll's expereince with a dubious rucksack so I'm still wondering where it came from. I am trying to get a sample of 10mm static back that I'd left outdoors for 7 years but foolishly lent to someone to tie down their car boot but I fear it's gone for ever. Having swung about on it, I'm pretty sure it wasn't showing anything like the degradation of the rucksack material.

 

[potholer]

Tent fabric can certainly fail after exposure to UV, but tent fabric is rather thin.

How far into a rope would UV actually penetrate?
Would it *ever* reach the core in significant amounts, and even if it did, assuming there's at least some significant attentuation going on with depth, would the sheath be close to falling apart by that point due to the much higher UV it would have encountered?
Would mild mud-staining in the sheath actually be protective?