rope age

[Geoff R]

Is a discussion on how rope degrades really the issue ? 

Equally I can see that rope drop testing is great to establish facts and review matters long term and highlight to people the serious risk of  using relatively new looking (but old) rope, but surely this should be the SOLE extent of its use.  It is indeed just testing that one section of rope that is under test. 

GREAT if it was a manufactures large batch of rope that is uniform and consistent  ie unused, where such >repeat< tests on such unused long rope provide a consistent result for that manufactured large batch.

POOR if it?s a cavers rope with differing in-service usage and experiences along its 50m length and this one test will be used to extend the life of this one (cheap bit of) rope.

Surely the question of when to replace ?50 - ?100 of rope after X years is more determined by you personally wanting to be totally above reproach in case of an accident. I assume this as we SRT as a group with other people using our rope (or Club rope),  so whether a Club official or private rope owner we have a major responsibility to others.

Taking account of manufacturers guidelines, can anyone tell me if there a stated time period or recommended number of trips usage for replacing  a) club rope and  b) individually owned rope,  issued by any UK caving ?authority? that would hold sway in a UK Court of Law AND what is the replacement requirements for UK industrial rope access ??

Surely with others caving on our ropes, this should be the sole basis of our >maximum time< replacement decision ?





 

 

[Geoff R]

Surely the question of when to replace ?50 - ?100 of rope after X years is more determined by you personally wanting to be totally above reproach in case of an accident. I assume this as we SRT as a group with other people using our rope (or Club rope),  so whether a Club official or private rope owner we have a major responsibility to others.

Taking account of manufacturers guidelines, can anyone tell me if there a stated time period or recommended number of trips usage for replacing  a) club rope and  b) individually owned rope,  issued by any UK caving ?authority? that would hold sway in a UK Court of Law AND what is the replacement requirements for UK industrial rope access ??

Surely with others caving on our ropes, this should be the sole basis of our >maximum time< replacement decision ?

Mammut state (extract from publication ......http://www.mammut.ch/mammut/uploadedFiles/seilfibel_030617-E-PDF(2).pdf

Independent of frequency of use, a rope should be disposed of / retired if

? The rope comes in contact with chemicals, particularly acids.
? The sheath is damaged and the core is visible.
? The sheath is extremely worn, or particularly fuzzy.
? The sheath has slipped noticeably.
? Strong deformations are present (stiffness, nicks, sponginess).
? The rope has been subjected to extreme loads (e.g. heavy falls, clearly over fall factor 1).
? The rope is extremely dirty (grease, oil, tar).
? Heat, abrasion or friction burns have caused damage.

The following table gives reference values for a ropes approximate lifespan given NONE of the above have occurred:

FREQUENCY OF USE APPROXIMATE LIFE SPAN
Never Used 10 years maximum
Rarely Used: twice per year Up to 7 years
Occasionally Used: once per month Up to 5 years
Regularly Used: several times per month Up to 3 years
Frequently Used: every week Up to 1 year
Constantly Used: almost daily Less than 1 year

 

[Geoff R]

And adding BEAL's view of lifetime

http://www.beal-services.info/index3.php?langue=lg2&categorie=cat_1


BEAL SEMI-STATIC ROPES LIFETIME

Lifetime = Time of storage before first use + time in use.
? The working life depends on the frequency and the type of use.
? Abrasion, UV exposure and humidity gradually degrade the properties of the rope.
? Note that with use, a rope thickens and thus loses up to 10 % length.
? Storage time: In good storage conditions this product may be kept for 5 years before first use without affecting its future lifetime duration in use.

(Beal) Lifetime:

- Intensive and daily use:      6 months
- Daily use of average intensity:    1 year
- Weekly and intensive use:        1 year
- Weekly use of average intensity:        2 years
- Periodic daily use of average intensity:      3 years
- Several uses during the year of average intensity:      5 years
- Very occasional light use:      10 years.



Attention: These are the nominal lifetimes indicated, a rope could be destroyed during its first use. It is the inspections which determine if the product must be scrapped more quickly. Proper storage between uses is essential. The lifetime of the rope in use must never exceed 10 years. The total maximum lifetime (storage before use + lifetime in use) is thus limited to 15 years.

The rope must be retired immediately:
- if it has held a fall
- if inspection reveals or even indicates damage to the core
- if the sheath is very worn
- if it has been in contact with any active or dangerous chemicals.
- if there is the slightest doubt about its security.


( Im not suggesting any variation in advise is relevent to rope choice, as they practically agree )

 

[mak]

This scheme relies on a basic assumption, that the test gives a fully representative idea of the condition of the whole rope. I don't believe that assumption is necessarily valid.

A simple counter-example is isolated damage to a particlar part of the rope. The damage might be visible and picked up by inspection or it might not. This whole discussion revolves around the basic premise that a rope can look OK but in fact not be OK. You can't simply reverse that argument and say "if one bit of the rope is OK, so must all the rest be".

Apart from isolated damaged (possibly cause by abrasion, falling etc.), ropes are not used or worn equally throughout their length. The bits near the end don't tend to get abseiled/prussiked on much, but on the other hand they get knots tied and loaded on them much more. Or they can get coiled and hung up in the sun, with the outside coils getting toasted while the inside ones are in the shade (or any one of a hundred other things which might lead to uneven deterioration over the length of the rope). Obviously we want to try and test the weakest part of the rope (a chain is only as strong as its weakest link), but what empirical evidence is available which suggests that the middle of the rope is necessarily going to be the weakest part?

Busting one piece of rope also gives you only one piece of data. Obviously you try to control the experiment and make it as "standard" as possible, but there will still be experimental variation.

So I'm sceptical about drop testing as a very useful tool for improving safety. A more pragmatic approach is to have a large safety margin and use ropes for caving which are much stronger than the loads likely to be applied to them, so that unexpected damage or wear is not disastrous. That's a practical approach which has served the caving community excellently over the years. I know of many clubs which operate around a 5 or 6 year cycle for rope replacement and the empirical data here is overwhelming - SRT ropes don't break on a regular basis. In fact they don't break AT ALL unless you do something really stupid.

Mark

Perhaps I should have highlighted the "loss of strength as ropes age and the expense of early retirement/replacement " and "NB still must visually inspect the ropes regularly" bits of my post, although I should have written "thorough insepection"

I was not suggesting that drop testing becomes the only means of checking a rope - all the other advice still stands re falls, damage, chemical exposure etc. etc.

I was merely suggesting that if it has passed all those tests and you run a scheme of replacement within the recommended lifetime of the rope then you could potentially extend the life of the rope by cutting up and drop testing a section - I suggested the middle to maximise the useability of the remaining lengths but If you wanted you might also consider sections near the end, and drop test more than one section.

This does not guarantee the whole rope is safe (only testing the whole rope section by section will do this) but will give an insight into the condition of the rope as a whole.

But I do think that drop testing, thorough inspection (oh and some knowledge of the ropes use over it's life) should allow the safe extension of the ropes life.

Remember the manufacturers decision to specify an age (and loading etc.) for the rope is driven by two factors - the fear of being sued and the desire to sell more rope so they have already built in a large margin of safety for both age and loading.

And I think as cavers we have to have a pragmatic view on this - if you personally want to have enough rope to do a range of trips in the UK then this will add up to quite a bit more than ?50 to ?100 in total, replacing this every 2 years will cost a lot more than replacing it every 10 years.

I seem to recall in all the years of drop testing by the NCA/BCA, the vast majority of failures within life (if not all?) have been where ropes have visible/noticeable signs of damage.

 

[Downer]

Is a discussion on how rope degrades really the issue ?

Yes as that's specifically what I asked.

 

[Downer]

Mammut state (extract from publication ......http://www.mammut.ch/mammut/uploadedFiles/seilfibel_030617-E-PDF(2).pdf
FREQUENCY OF USE APPROXIMATE LIFE SPAN
Never Used 10 years maximum

[Rank incredulity!!!] Now why would a manufacturer insist you buy new ropes from them every ten years even if they're not used?

More usefully -
"UV radiation from the sun causes colors to
fade and accelerates aging. However, the
radiation to which a climbing rope is subjected
in use has a negligible effect on strength,
though the fibers do lose elasticity and the
rope becomes stiffer. More dubious are the
completely bleached rope rappel slings that
can be found on some routes, though even
these will normally hold a standard static
load."

 

[ian.p]

Now why would a manufacturer insist you buy new ropes from them every ten years even if they're not used?

why would you want to buy a new one if you hadnt got round to using the old one in ten years??

 

[Downer]

Now why would a manufacturer insist you buy new ropes from them every ten years even if they're not used?

why would you want to buy a new one if you hadnt got round to using the old one in ten years??

Of course, I wouldn't want to. But I dare say Mammut would like me to.

 

[Geoff R]

Beal by using the words "very occasional light use" are also effectively saying 10 years - this figure is consistent, although Beal do go on and say a maximum of 15 (with no use !!!)

More relevant is Beal and Mammut close consistency over periods of normal rope usage ! 


BTY, does anyone know the answer to ....

Taking account of manufacturers guidelines, can anyone tell me if there a stated time period or recommended number of trips usage for replacing  a) club rope and  b) individually owned rope,  issued by any UK caving ?authority? that would hold sway in a UK Court of Law AND what is the replacement requirements for UK industrial rope access ??

Surely with others caving on our ropes, this should be the sole basis of our >maximum time< replacement decision ?

 

Thanks

 

[cap n chris]

Now why would a manufacturer insist you buy new ropes from them every ten years even if they're not used?

why would you want to buy a new one if you hadnt got round to using the old one in ten years??

If you haven't used a rope in ten years you probably no longer need any - new or old!

 

[ian.p]

my point exactly

 

[ianball11]

I own Marlow and cant see anything on their website about suggested lifespans of their static ropes.  :-\

Do the HSE cover rope access legislation? Sorry, I've no time to look at their website but sounds right and I think a search of the forum would bring it up as well.

Must dash,

Ian B.

 

[nickwilliams]

Remember the manufacturers decision to specify an age (and loading etc.) for the rope is driven by two factors - the fear of being sued and the desire to sell more rope so they have already built in a large margin of safety for both age and loading.

I don't disagree with much, if any, of the rest of your posting, but I feel I should point out that the main reason that rope manufacturers specify an age limit for their products is because the PPE Directive requires them to.

Nick.

 

[Wolf]

why is it so difficult to understand that that the labels on the the rope regards to properties that a new rope has. everything is ageing (as we all do) and therefore also a rope has a specific lifetime where it can be used. the question is at what age of the rope (not of the caver) the remaining stability is sufficient (for the designated use). in my eyes when you really plan to fall into a rope (ff >1) than you shouldn't do that with a speleo rope.  there are formulas out there, how to estimate the forces that your rope has to stand. just getting up or down a fixed rope results in max. 2x your weight. if you add a rescue situation where 2 persons hang at the same rope, then double that value and you are at approx 300 kg (unless unnecessary overweight). what is the minimum break load for a new rope? around 2000 kg. so in our use of the ropes there is plenty of safety included. it might be a bit different if you use the rope for a cable way, where the low angle between the horizon and the rope leads to an increase of load.

so just make sure that anybody knows that the promised properties regard to a new rope and that they decline with age! Everybody who is in charge of the use of a rope should be able to estimate what forces will be applied to a rope (and also should be able to estimate what strength is left due to ageing). Therefore short renewal periods in clubs are not the worst decision, where nobody likes to know what has been done with the rope or will be done to the rope.

Within plain srt you will hardly break a rope.

 

[Downer]

why is it so difficult to understand that that the labels on the the rope regards to properties that a new rope has. everything is ageing (as we all do) and therefore also a rope has a specific lifetime where it can be used.

Because not all things age at anything like the same rate. The lifetime of nylon rope might have been a billion years or it might have been a week. It seems very convenient that it should happen to be just the right value to ensure continued sales while still allowing the stuff to be used for a practical time.

 

[cap n chris]

"It seems very convenient that it should happen to be just the right value to ensure continued sales while still allowing the stuff to be used for a practical time"

A very convenient truth, perhaps.

A bit like clothes, food, cars, electrical goods etc., then? 

 

[Downer]

"It seems very convenient that it should happen to be just the right value to ensure continued sales while still allowing the stuff to be used for a practical time"

A very convenient truth, perhaps.

A bit like clothes, food, cars, electrical goods etc., then? 

Aye. There's no law of nature that says your car will wear out just when you've finished paying for it. A Formula One engine is designed to last 3 hours, a road car lasts about 1000 times as long and I don't doubt Victorian steam engines would still be running if internal combustion hadn't rendered them obsolete. It just depends what criteria - cost, power, weight, life - the design team use. Electrical goods are made for a throw-away cash economy, 'nuff said. Food, however, biodegrades because of little rotting machines which we have no control over. They have honed their chemistry over 4 billion years of evolution to the business of survival, not to the market. So the bugs multiply flat out and food rots far faster than you and I would like it to. Not on a 5-year replacement cycle, that for sure.

Rope, however, is synthetic so the chemists have a free hand to engineer it as they wish. There is no obvious reason why its inherent rate of degradion should be similar to its physical wear rate, yet this miracle of fine-tuning has happened all on its own! It's not impossible, just a bit fishy.

 

[cap n chris]

You're too clever for me. Be applauded once more!

 

[Downer]

You're too clever for me. Be applauded once more!

Oh no, not more karma. I hate karma.