Retiring slings

I have a handful of BD dyneema slings that are over 5 years ago. On a recent rock rescue course the guide recommended retiring slings that are over 5 years old due to the natural breakdown of the material.

Does everyone actually follow this rule? Has there been any lab tests where they test the strength or durability long term?

I have some slings that I bought and rarely used, so I would hate to have to throw out a sling that is basically new, but old in terms of age...

Keep in mind that anyone in any sort of "official capacity" is going to be every bit as conservative in this regard as the gear manufacturers.  I am absolutely certain that the slings are good to use for longer than 5 years.  I think the weight of the evidence is that USE is more responsible for Dyneema weakening over time than age alone. Phrases like "natural breakdown" are IMO not helpful when discussing this.  

Having said that, I have several virtually unused 8-10 yr old (maybe longer) Dyneema slings that I'm not allowed to use in my professional setting. Is there anyone out there who can do a pull test on one of them?

Gunkiemike wrote:

I think the weight of the evidence is that USE is more responsible for Dyneema weakening over time than age alone. Phrases like "natural breakdown" are IMO not helpful when discussing this.

Agree on the "natural breakdown" bit; nylon at least seems to resist the passage of time reasonably well.  I'd love to see better data comparing used vs unused and well-stored Dyneema.  As best I can tell, Dyneema is pretty resistent to things like UV and chemicals and yet it seems to lose strength rather quickly, even when only lightly used.

Another item that came to mind was healyje's having some slings tested about a decade ago; after three years the tests showed around a 50% strength reduction.  More at http://www.supertopo.com/climbing/thread.php?topic_id=269434&tn=40 (scroll down).

I think all my slings are over 5 years old, owing to favourable exchange rate I stocked up hard at the time.

Seems a bit wrong to throw out the hardly or not at all used ones! They're in better condition than what a lot of people carry, age aside.

Jeremy B. wrote:

Another item that came to mind was healyje's having some slings tested about a decade ago; after three years the tests showed around a 50% strength reduction.  More at http://www.supertopo.com/climbing/thread.php?topic_id=269434&tn=40 (scroll down).

I REALLY wish I kept the numbers, but about the time Joe shared his sling data, I tested a skinny sling of equal-or-greater age that had seen much less use.  It was a lot stronger than Joe's trend would suggest. That's a big part of why I believe it's USE rather than AGE that determines lifespan of the skinny stuff.

And I'll repeat my request for someone to pull test a 10+ y.o. Dyneema sling.

Last year I pulled apart 3 slings that were no more than 5 years old. They were white and yellow mammut 60cm slings that I bought in 2012. They had plenty of use but were not damaged at all. Anyways with 3/8" quick links on each end and using a binder setup with a rockexotica enforcer, they all failed between 12kn and 12.5kn.  

Jeremy B. wrote:

Agree on the "natural breakdown" bit; nylon at least seems to resist the passage of time reasonably well.  I'd love to see better data comparing used vs unused and well-stored Dyneema.  As best I can tell, Dyneema is pretty resistent to things like UV and chemicals and yet it seems to lose strength rather quickly, even when only lightly used.

Another item that came to mind was healyje's having some slings tested about a decade ago; after three years the tests showed around a 50% strength reduction.  More at http://www.supertopo.com/climbing/thread.php?topic_id=269434&tn=40 (scroll down).

actually nylon doesn't degrade at all with time, only abrasion and UV degradation. Dyneema, I don't know but I would expect it is the same. 

 http://www.siebert.at/de/publikationen/66/Masterarbeit-zur-Ablegereife-von-PSA

It really should not be a surprise that really light, low bulk gear doesn't last as long:

http://www.heeresbergfuehrer.at/Archiv/TextuFotos/Ablage/2016/16Gebrauchsdauer%20von%20Bandschlingen.pdf from

https://www.alpenverein.de/chameleon/public/ebefc557-b30d-8e66-6229-76efab14e96e/DAV-Panorama-4-2015-Komplettversion_26112.pdf

(German language articles...)

dave custer wrote:

(German language articles...)

It's ok; the first link I posted is a translation of those.   

eli poss wrote:

actually nylon doesn't degrade at all with time, only abrasion and UV degradation. Dyneema, I don't know but I would expect it is the same. 

 http://www.siebert.at/de/publikationen/66/Masterarbeit-zur-Ablegereife-von-PSA

My German is nonexistent, but what I'm getting from this is that ropes and harnesses tend to remain safe far beyond the stated timelines (i.e. if they look good, they probably are good).  However, (and I believe this paper mainly examined nylon materials), it does note that slings don't seem to be in this category.  I also noticed a suggestion that it may be due to the load-bearing core of ropes being shielded from UV and abrasion, whereas the load-bearing components of slings are exposed.

Following a trail from one of the references, I also see an article on older slings that goes into this a bit; it mentions that PE is rather UV-permeable, and that while pure PE doesn't absorb much UV, structural defects apparently make this not the case in practice.  So, one more German article: http://www.bergundsteigen.at/file.php/archiv/2014/3/54-59%28alte%20schlingen%20und%20reepschnuere%29.pdf (unfortunately without translation).

Gunkiemike wrote:

I REALLY wish I kept the numbers, but about the time Joe shared his sling data, I tested a skinny sling of equal-or-greater age that had seen much less use.  It was a lot stronger than Joe's trend would suggest. That's a big part of why I believe it's USE rather than AGE that determines lifespan of the skinny stuff.

And I'll repeat my request for someone to pull test a 10+ y.o. Dyneema sling.

I would be happy to shop test gear. I have calibrated analog and digital dynomometers to 15klbs, $8.00 per test for slings up to 20 feet long.

I routinely load test fastenings (mechanical and adhesive) and equipment for commercial roof anchorage, fall protection, rope access, material handling etc.

Give a pm if interested

Stever wrote:

On a recent rock rescue course the guide recommended retiring slings that are over 5 years old due to the natural breakdown of the material.

UHMWPE (Dyneema) does not "naturally breakdown." A 5-year old spool of brand new Dyneema rope will test out around the same strength as one made today.

Anyway, the answer is no, I dont retire any gear under any circumstance just because it's X number of years old. That's just not how things work. The material used in climbing equipment does not degrade solely because it's gotten older. It degrades with abrasion, UV exposure and heavy use, but not time. I retire gear when it's worn to the point that it's no longer serviceable. If your slings still look fine and are not all fuzzy, then they are fine. If they are all fuzzy and torn up, then consider replacing them.

Jeremy B. wrote:

My German is nonexistent, but what I'm getting from this is that ropes and harnesses tend to remain safe far beyond the stated timelines (i.e. if they look good, they probably are good).  However, (and I believe this paper mainly examined nylon materials), it does note that slings don't seem to be in this category.  I also noticed a suggestion that it may be due to the load-bearing core of ropes being shielded from UV and abrasion, whereas the load-bearing components of slings are exposed.

Following a trail from one of the references, I also see an article on older slings that goes into this a bit; it mentions that PE is rather UV-permeable, and that while pure PE doesn't absorb much UV, structural defects apparently make this not the case in practice.  So, one more German article: http://www.bergundsteigen.at/file.php/archiv/2014/3/54-59%28alte%20schlingen%20und%20reepschnuere%29.pdf (unfortunately without translation).

I don't know if this specific paper covered slings but he tested slings, ropes, harness, etc. The conclusion is that age doesn't matter and slings that are sun bleached or fuzzy are weaker. He also found that holding a major load (90% of breaking strength) doesn't seem to affect the breaking strength of slings or ropes. He used to have really good videos in English that spelled everything out on youtube but I can't seem to find them.

Gunkiemike wrote:

I REALLY wish I kept the numbers, but about the time Joe shared his sling data, I tested a skinny sling of equal-or-greater age that had seen much less use.  It was a lot stronger than Joe's trend would suggest. That's a big part of why I believe it's USE rather than AGE that determines lifespan of the skinny stuff.

And I'll repeat my request for someone to pull test a 10+ y.o. Dyneema sling.

I´ve tested maybe half a dozen 12mm Dyneema hybrid slings which were between ten and fifteen years old and gone real furry, they all seem to hang in there to about 12-13kN and the less used but equally as old ones get up towards 16kN.

The seatbelts in my car are well over 5 years old ad are approaching 10 years....and I store them in the sun, in my hot car. 

M Hanna wrote:

I would be happy to shop test gear. I have calibrated analog and digital dynomometers to 15klbs, $8.00 per test for slings up to 20 feet long.

I routinely load test fastenings (mechanical and adhesive) and equipment for commercial roof anchorage, fall protection, rope access, material handling etc.

Give a pm if interested

Maybe in the interest of public service, I'll donate the sling/associated postage, and you donate the testing?

Since public interest: I'll donate / venmo either of you $30 for testing / material. Maybe more people can chip in. 

eli poss wrote:

actually nylon doesn't degrade at all with time, only abrasion and UV degradation. Dyneema, I don't know but I would expect it is the same. 

 http://www.siebert.at/de/publikationen/66/Masterarbeit-zur-Ablegereife-von-PSA

Here's some info on Nylon strength loss due to use:

http://itrsonline.org/wordpress/wp-content/uploads/2016/11/Evans.Truebe_Strength-Loss-Due-To-Aging-of-1-Inch-Tubular-Nylon-Webbing-paper.pdf

When to retire webbing is a personal choice. Generally, if in doubt, throw it out. And obviously, if the webbing has received some sort of damage (e.g., cuts, abrasion, dissolution from acid, etc.), it should be retired. However, for webbing that has been used reasonably, has not experienced shock loads, and is well maintained, a rigger can decide how much strength loss(on average) they are willing to accept in their equipment before retiring it. No rule will be advocated here, other than imploring users to base their decisions on data. It is hoped that this short article provides just the kind of information users may need to make these kinds of decisions.

M Hanna wrote:

I would be happy to shop test gear. I have calibrated analog and digital dynomometers to 15klbs, $8.00 per test for slings up to 20 feet long.

I routinely load test fastenings (mechanical and adhesive) and equipment for commercial roof anchorage, fall protection, rope access, material handling etc.

Give a pm if interested

I'm interested.  Ready to send you slings, in fact.  Sent you a PM.