Torn Webbing on a Tri-cam during a fall

Don't get me wrong I appreciate the suggestion. If anyone else has any ideas as to what might cause such a failure then I will try to devise a way to test the theory.

Darren B. wrote:I purchased the cam used, so I couldn't tell you the age. I've certainly changed my attitude about used gear now and will be much more selective when purchasing anything used.

Used gear with unknown history... hmmm. Could be the culprit.

can you tell if there was any UV degradation?

Aric Datesman wrote:Hey Esha, I case you've note seen it, BD has a very good 11 page analysis of a rope that severed due to acid exposure a couple years ago. Well worth a read. Link (PDF)

As a former analytical chemist, I say that is not a good report vis-a-vis the sulfuric acid statement. They tdon't indicate how the acid was detected, nor do they provide supporting data (Xray fluorescence, XPS etc). Many SEM machines can do this, so the lack of sulfur evidence is particularly disturbing.

Along these same lines, Esha, can you describe how you looked for sulfuric acid on the sling?

esha wrote:Don't get me wrong I appreciate the suggestion. If anyone else has any ideas as to what might cause such a failure then I will try to devise a way to test the theory.

Pull test a tricam at an angle, per my theory above.

Gunkiemike wrote: As a former analytical chemist....

Chemistry was never my strong suit, so thanks for your insight, Mike. The think I liked about the report were the clear photos showing the difference in failure mode between the effected and uneffected nylon (clean break vs stretch&melt). Seems to me the difference was quite noticeable and should be fairly easy to see under magnification (with a clean break implying a cut or contamination). While I may have found a description of the methods used to detect acid exposure interesting, most likely it would have been way over my head so have to trust that the lab BD sent it to knew what they were doing. Given your background I can see how you may want to see that kind of thing.

-aric.

This is all damn fascinating. Thanks very much to esha for the chem testing. Like you said, e, this leaves more questions than answers.

Anyone else have any takeaways from this situation? Should I junk all my used gear and start rebuilding my rack from new? Spring cams don't have the same point of contact as the tricams. Should I ween myself off my beloved tricams and onto the springy thingies?

Perhaps this should be filed under the "Shit Happens" category and leave it at that... I know that climbing is a numbers game (as is life!), but I'd hate to think that I'm hedging my bet negatively by using this gear.

db

Yes, also thanks to esha for taking the time to do some testing.

you'd need some pull & drop testing to look at gear failures from that levered angle. I don't have anything astoundingly new that hasn't already been discussed.

Maybe type of system -- dynamic or static/low stretch, was it a free-fall for acceleration, & mass amount; something putting forces greater than what the gear is intended that wasn't already considered.

Could be gear outside the norm manufacturing specs for a tri-cam being defective to being with, something in the material manufacturing process.

guys why dont you just mail it to camp USA with a link to this discussion and a letter explaining what happened

im sure theyll have a look ... if i were them i wouldnt want people speculating about who knows what about my products ... better to solve and settle it once and for all

sorry everyone, i don't keep up with the forums over the weekend. to whoever wanted to know the testing methods, the following were performed. i didn't consider a forum like this would require a full lab report considering most everyone on this site will not have a clue (nor will the probably care) what i am talking about, but anyway:

microscope analysis to look at the ends of the threads were the break occurred.

ATR scan doesn't indicate a broad OH stretch that could indicate H2O, or an acid group, nor is there any S=O peaks.

i soaked the sling thoroughly in water with sonication to try and remove any water soluble contaminants, the pH was checked against a USP water standard, no pH change indicated.

the water from the sling soaking was scanned by UV-Vis from 200-800 nm, the only peak seen was almost certainly residual red dye from the sling.

if you have any other ideas then let me know, if i have the instrumentation available then i will run the analysis.

ok, i started thinking about this a little more and i fear i have missed a big possibility (as it goes in science, there is almost always an argument to derail any theory). i feel pretty stupid here for not considering this before, but there is a possibility that the sulfuric acid could have degraded over time, most of the by-products would have been volatile (and therefore gone now) and the only thing left (i think, please correct me if i am wrong) would be sulfur. unfortunately i have no way to test for that in my lab. i am sure it could be sent out for analysis at another lab, but they would probably not be willing to do it for free (if anyone knows anyone who might be willing to run the analysis for free then let me know and i will ship it to them). since the cost is an issue, i am curios, but not that curios.

to answer the other question about the possibility of UV degradation, the short answer is i doubt it. it would take a considerable amount of sunlight to deteriorate the sling to the point where it would have failed like this, and in my experience such deterioration is usually evident due to a fading in the slings original color. there was no evidence of this at all upon visual inspection, but i guess we can't rule it out completely. without knowing a lot about polymers, and how light effects their chemical structure, it would be difficult for me to further test this theory. once again, if anyone knows anyone in the business who could test this let me know.

i am going to return the sling to the OP, and he can do what he likes with it, including sending it back to CAMP, which i think is a fine idea. i fear they would merely returned another analysis that would be lacking in details to prove their theory, like in the BD report linked to in this thread.

obviously you're not a golfer.

Eager as i am to home-resling my eBay double rack of tricams, I don't think this was the nylon's fault.  Look at where the break is - it's not symmetrical at the end of the loop.  If the nylon was not being cut by the roll pin, i expect the break would be at the very tip of the loop that holds the pin, i.e. symmetrical.  This leads me to believe the break was initiated by a slice from the roll pin, as a few others have suggested earlier.

I could be wrong about this.  I haven't watched how-not-to-highline in a while, I don't remember how ropes break around a radius, but i expect it would be at the tip of the radius.  Also, that slings that "broke" in the show, were way more frizzy.