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gunsmokex

Shelf life on containers?

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Simple question, probably a complicated answer. Talking with my rigger he stated that the webbing over 20 yrs loses 1/2 of its strength. Is this true?!? Just wondering because my container is from the mid 90's and that statement worries me....a lot.

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1 hour ago, gunsmokex said:

Simple question, probably a complicated answer. Talking with my rigger he stated that the webbing over 20 yrs loses 1/2 of its strength. Is this true?!? Just wondering because my container is from the mid 90's and that statement worries me....a lot.

If that statement was correct, we would be having people falling out of harnesses every other weekend...

I have no problem working on "closet queens" from the 90's, as long as people understand the limitation on the rigs build back then.

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There's a BPA skydive the expo 2019 video that explain the aging process of harness in a DZ in the UK. I can't remember the specifics without re-watching the entire video but they are installing new harnesses every 2000 jumps because they saw a 50% reduction in strength of the webbing. UV exposure and the environment was playing a major factor for them.

Remember that the webbing used in skydiving has a high tensile strength. Riggers could comment on the strength of each and every webbing type but even when it loses 50% there is still a safety factor present.
According to Paragear
Type 8 when new= 4000 lbs  
Type 17 when new= 2500 lbs

We won't go into the fact that webbing can be loaded differently due to body position but a rough estimate would be:
Safety factor = strength of weakest webbing / exit weight

I think this is the video in question

 

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(edited)

20 years of heavy use, getting fuzzed up from wear or heavily faded from sunlight, sure one could have webbing lose half its strength. 

Look for the "Wilcox Webbing Tests". (Old Skydiving Magazine article and also a PIA presentation. Might still be kicking around the web. )

But there's also data from government and military testing suggesting that one might lose only say under 2% of strength per decade, if not stored in too hot conditions. That's the closet queen scenario, without sun and dirt and wear.  (This has been in older threads I've been involved with, but I'm not dredging up the data right now.)

Nylon does degrade and oxidize over time, and the chemical processes are speeded up with heat. But it is a slow, slow process.

Edited by pchapman

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If stored in their original plastic bag and shelved in a cool, dry, dark warehouse, parachutes can easily last 30 or 40 years.

How it is used after it is placed in service makes a huuuuuuuuge difference. If students drag it through sand, thorns, barbed wire fences and leave it laying in the sun all day, you are lucky to get more than 1 year’s service/

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On 3/29/2019 at 2:49 PM, pchapman said:

20 years of heavy use, getting fuzzed up from wear or heavily faded from sunlight, sure one could have webbing lose half its strength.

Yeah, but is it the "20 years" or the "heavy use, getting fuzzed up from wear or heavily faded from sunlight" that's at the root of the strength loss?

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I know you were asking about condition and much ink has been spilt on that both here and elsewhere...

But another aspect of this to consider...

Over 20 years there are many changes to what people do with their rigs and the average knowledge of the jumper/DZ staff and riggers...  Freefly friendly, AAD support, factory support (they have staff-turnover too), techniques needed that aren't in the older manuals (both packing and use).  I know a rigger that still jumps his prestine Sweethogs (look it up ya pup). But he isn't sit-flying either (and had the original mfg retrofit it for Cypres).  Would I still jump my Vector II, yea... but I know its limitations.

Would I recommend that EBay closet-queen special Strong Hawk, FXC, 26' Lopo with a Nova in it to a newbie who wants to freefly at a "young DZ"... that's a different story.

Just sayin'

JW

 

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On 4/17/2019 at 11:44 AM, riggerrob said:

Once fading is visible, strength has deteriorated by half.

really Rob? So a harness that was made from neon pink that shows fading within 6 months has lost half it's strength while the black harness still looks great after 10 years hasn't lost anything?

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20 hours ago, linestretch said:

really Rob? So a harness that was made from neon pink that shows fading within 6 months has lost half it's strength while the black harness still looks great after 10 years hasn't lost anything?

No, fading of the dye and degradation of the nylon are two different things. But we can't pull test webbing so fading is the only indication of sun (uv) exposure. No I don't agree.with Rob. It might be true for black. For neon pink no. 

And.to OP an unused harness stored properly does NOT lose half of its strength in 20 years. 

But remember I can think of only two.properly constructed harnesses that have failed in my 40 year career.

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Can people point me to some studies to back up strength loss over time.   I have seen studies reflecting strength.loss of nylon due to uv exposure and other chemical actions but how much has been done on age deterioration only.

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Update I actually found a 10 yr Vector II closet queen with just the container (made in 1996 and put away in 2006). Just have to swap out the freebag, reserve pc, AAD and the 'new' container even once had an RSL so the same components should work from my old container which I had an RSL added onto the new one. Velcro is new, container even looks "fresh". Thanks for all of the input I just didn't really realize that webbing loses 1/2 its strength under the right conditions.

I'm very happy with this container its being put together right now.

I can see how UV ray exposure, use and abuse would decrease the webbing strength. It'd be interesting to review those 2 harness failures.

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Mr. gunsmokex,

Warehoused harnesses lose little strength over 20 years.

OTOH In service, one summer laying out it the sun can ruin a harness. The simplest inspection technique is comparing fading on the front side and the back side of the same reserve riser.

Yes, neon colours lose their “sheen” much faster, so fading is a less accurate way to measure their strength. I have seen neon rigs lose their sheen in as little as a single year (Southern California Desert), but they were still strong enough for another thousand jumps.

The other problem with 20+ year old rigs is that they have fallen out of fashion. While they might still be relevant for belly-flying, they may not be for more recent styles of skydiving.

I can show you a badly-torn Vector II. During a sit-fly jump, the main pilot chute snuck out of its pocket (leg strap) and the deploying main ripped the reserve container halfway off the backpad! Only stitching was damaged. I had the sewing machines and skills to sew it back together, but advised the owner to buy a newer design that was more free-fly-friendly.

Fortunately the reserve free bag and canopy were undamaged, but by then its Raven III (249 square feet) had been superseded by a couple of generations of reserves designed to be loaded more than 1/1.

We also salvaged its Cypres.

Funny how we rarely hear the term “free-fly-friendly” these days. Once the problem areas were recognized, “fixes” quickly became “production standard” across the industry.

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Thanks Rob, yeah i don't plan on free flying anytime soon. My goal this year is to get into a wingsuit and keep working on my belly skills. If I did freefly then I'd definitely buy a container designed for that discipline deployment @ 160+mph doesn't sound like fun especially with a Hornet.

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>But remember I can think of only two.properly constructed harnesses that have failed in my 40 year career.

Councilman, was it the stitching that failed or the actual webbing?  If the webbing, type 7 or 8?  Anything noteworthy you can recall??

Thanks!

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