Flattening of cordage by descending rings

[DemostiX]

I am trying to find the problem[ in the thread the Mod found, replying to a current expression of concern about the effects of some fasteners on cord] of "flattening" of Amsteel and related cordage . I see an action closer to cutting, with some of the devices including edges resembling those on nippers.

But damage to current Dyneema / Spectra -based from flattening between rings? Some specifics, so that we can see the action causing the fault was correctly described and that is is applicable to current cord?

[NCPatrick]

Here's another past discussion. It seems some that flattening does occur to the Amsteel, by the rings, in a worrisome manner.

http://www.hammockforums.net/forum/s...ead.php?t=8062

[DemostiX]

Here's another past discussion. It seems some that flattening does occur to the Amsteel, by the rings, in a worrisome manner.

http://www.hammockforums.net/forum/s...ead.php?t=8062

I find only one observation. Grizzly Adams expresses worry to see flattening, but he doesn't know that the Amsteel line has been compromised. Neither do I. He also doesn't say what the line is, except for the material.

I am much more concerned, today about rough metal and sharp edges and the the risk they pose to cord. The major study of Amsteel anchor lines by Samson after years of field service concluded that poor maintenance of surfaces and resultant abrasion was a major source of wear. Was there even a % put on it? I know Samson publishes protocols for re-finishing of drums due to that threat. I've seen new hardware that was threatening to cord, without corrosion. Nothing like the engineered surfaces and edges of climbing and rescue carabiners.
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Because some statements were cited, incidentally, from an old thread:

Gizz's remarks comparing Amsteel Blue and Vectran on strength better apply to the competitive cords. Single-braided Vectran rope is never as strong as Dyneema / Spectra, strength per gram, because it is 40% more dense than UHDMWPE (Dyneema, Spectra). So, for weight weenies, cord size for cord size, across mfgs, Dyneema-based line is always considerably lighter.

What Vectran is prized for is its lower or absent creep. Vectran in tension and over time does not grow longer.

[NCPatrick]

I split off this discussion as it was taking the other thread into an in-depth discussion better addressed in it's own thread.

[NCPatrick]

Here's a few other threads discussing it. Sorry, I'm not an expert on the subject -- best I can do is point you to threads where it is being discussed.

http://www.hammockforums.net/forum/s...545#post308545

http://www.hammockforums.net/forum/s...ead.php?t=9448

[NCPatrick]

I am much more concerned, today about rough metal and sharp edges and the the risk they pose to cord. The major study of Amsteel anchor lines by Samson after years of field service concluded that poor maintenance of surfaces and resultant abrasion was a major source of wear.

May I ask what you are using for rings? My SMC descending rings have no rough metal or rough edges to worry about. I have not seen the kind of surface wear on them that you describe above even after years of use.

[Cannibal]

I've seen wear similar to the issue DemostiX is discussing while using rings...sort of.

The tri-rings Warbonnet was using for a time had a weld that was raised. If the rings were not positioned correctly with the weld on one of the sides, instead of where the webbing/cord passed through, then you could see damage to the webbing/cord over time. For me, the issue was particular to webbing, but I could see how it would do the same to cord. The raised weld wasn't even really 'rough', but it was enough to produce visible wear in a short amount of time. Course, this assumes you are using the tri-rings incorrectly in the first place, so there is that. But, it's still enough to lend a little credence to the issue in question.

Warbonnet hasn't used those rings in a couple of years and I'm not aware of any hardware currently being used that has similar issues.

[Looknup]

What actually happened was I ordered a new WBBB and it came with Amsteel, about a 6 ft length, straight line, no loop. I had one Whoopie sling (I stupidly pulled the end through the restrictor on the second sling in the set so I ended up with an odd sling) so I put it on one end and left the other end like it came. I was using regular continuous loop aluminum decending rings attached to the tree hugger. What I noticed is where the line looped back through between the two rings is where it was being pinched and flattened. It held fine three or four times and it wasn't til then I noticed the flattening. I don't mind the flattening as long as it's not compromising the integrity of the Amsteel.

[NCPatrick]

Here's a video in which a polyester sleeve (around 2:20 in the video) is recommended to guard against chafing and catching from rough and/or sharp edges:



I found that on this site: http://www.gazela.slask.pl/video/3C8ZWRpUNPU.html

[DemostiX]

Amsteel Blue is designed to maximize strength over handling. As I understand rope braiding, that is achieved with fewer twists and a more relaxed structure.
By design, and especially because of the slipperiness of the fiber of Amsteel Blue, it WILL flatten more than a version of the same designed for handling and (lower proneness to snagging.) There's a difference between flattening rope explicitly made to stay round, and flattening a rope which is mostly about tensile strength and made of extremely strong fibers.

The larger the fid you can insert in the hollow braid, the more the strands can be pushed apart. If the fibers within the strand are inherrently slippery and the weave is loose, then yes, it will all slide wide and do so without internal abrasion of the strands and fibers, something that was the bane of early Aramid (Kevlar) ropes.