sobo Posted January 16, 2012 Share Posted January 16, 2012 claim failure... Or not... Quote Link to comment Share on other sites More sharing options...
JosephH Posted January 17, 2012 Share Posted January 17, 2012 I'd say it's most probably an open gate failure. I would also comment that's probably not the best choice for a slackline rigging biner. I've always used locking ovals for my rigs and locking steel ovals in high tension ones because I'm wary of potential weaknesses associated with the asymmetries of pear shaped biners for these applications. Quote Link to comment Share on other sites More sharing options...
Lodestone Posted January 17, 2012 Share Posted January 17, 2012 Jeffrey, what brand is the biner? Mad Rock Super-Tech-Keylock, a.k.a. Mad Rock Don't-Use-Me-For-A-Slackline http://www.madrockclimbing.com/products/product.asp?_item=100093 Quote Link to comment Share on other sites More sharing options...
genepires Posted January 17, 2012 Share Posted January 17, 2012 I'm wary of potential weaknesses associated with the asymmetries of pear shaped biners for these applications. Interesting thought. I believe that most biners are rated stronger than any aluminum ovals. Are you saying that asymmetric biners that are loaded in anything other than the usual way is weaker than ovals which are loaded perfectly quite easily? Quote Link to comment Share on other sites More sharing options...
pink Posted January 17, 2012 Share Posted January 17, 2012 (edited) One of my friends was slack-lining and had a carabiner snap. It was a fairly short line (no more than 30') and shouldn't have been under a huge load. Any thoughts...? this looks like one of those carabiners that dork's hang their keys from.... does it happen to have "not for climbing printed on the side" ? Edited January 17, 2012 by pink Quote Link to comment Share on other sites More sharing options...
tvashtarkatena Posted January 17, 2012 Share Posted January 17, 2012 (edited) Ovals are weaker because of their inherently large moment arm which pretty quickly weights the spine n gate equally and adds a lot of bending stress on top of the tensile stress already there. Most biners now put the line of tension as close as possible to the spine, which sometimes has a slight curvature for added strength ( like prestressed beams). And use the gate only for backup when there's enough deflection to engage it. The biner you used (locking version) is stronger than most - 24/8/9 kn, so it's not the biner. Steel biners can handle 72/22 kn, BTW. Expensive, but for this application it seems well worth it. Edited January 17, 2012 by tvashtarkatena Quote Link to comment Share on other sites More sharing options...
JosephH Posted January 17, 2012 Share Posted January 17, 2012 Ovals are weaker because of their inherently large moment arm which pretty quickly weights the spine n gate equally. Most biners now put the line of tension as close as possible to the spine, which sometimes has a slight curvature for added strength ( like prestressed beams). And use the gate only for backup when there's enough deflection to engage it. I don't doubt what you say, but particularly in my high tensioned rigs I prefer the clean symmetry of ovals relative to how and where the ropes / webbing lay in them. With pear biners rope / webbing can load strangely in the wide end if you aren't careful and I suspect that played a role in this broken one (other than just being a flat out cheap and cheesy piece of gear). Petzl locking ovals are 24kn and whatever their Oxan steel locking ovals rate at they are more than burly. Again, to each his own I suppose, but the for my own purposes I find particular comfort in the symmetry and clean rope / webbing lay in ovals and that opinion is born of thirty six years of rigging all manner of tightropes and slacklines without ever having a line failure. Quote Link to comment Share on other sites More sharing options...
tvashtarkatena Posted January 17, 2012 Share Posted January 17, 2012 (edited) Agree about the parabiner geometry. THis biner doesn't have it. It's geometry is excellent for the application, hence its higher rating. I already covered the webbing/knot/moment arm issue. I do things differently than I did 36 years ago, personally. Edited January 17, 2012 by tvashtarkatena Quote Link to comment Share on other sites More sharing options...
ryanb Posted January 17, 2012 Share Posted January 17, 2012 Was that carabiner loaded in 3 directions? Ie did your friend run a long runner around a tree clip it together and then tie the line off to it? I also ovals or old style D's for slacklines partly because they seem to have a wider loadable area for the one inch webbing (compared to the rope notch on many modern biners) which, wether it makes them stronger for this or not, makes it easier to keep the webbing flat and set up the tensioning system I use and partly because I've retired them from normal climbing use. I also double them up, partly for redundancy and partly because it makes it easier to get the knots undone. My tensioning system requires double carabiners on the tensioning end. Quote Link to comment Share on other sites More sharing options...
JosephH Posted January 17, 2012 Share Posted January 17, 2012 I do things differently than I did 36 years ago, personally. Why? Has something changed about slacklining or tightrope in the past 36 years that I missed? Can't think of anything off hand... Quote Link to comment Share on other sites More sharing options...
JeffreyR Posted January 19, 2012 Author Share Posted January 19, 2012 Thanks everyone for the information and discussion. This was not my setup (I was not even present) and always use stronger gear on my own setups, but I was still surprised at the manner of the failure. Quote Link to comment Share on other sites More sharing options...
JeffreyR Posted January 19, 2012 Author Share Posted January 19, 2012 Jeffrey, what brand is the biner? Mad Rock Super-Tech-Keylock, a.k.a. Mad Rock Don't-Use-Me-For-A-Slackline http://www.madrockclimbing.com/products/product.asp?_item=100093 Supposedly this brand is rated for 9 Kn with the gate open. It seems like it still should not have failed under these conditions. I am no engineer, but that is a good amount of force... Quote Link to comment Share on other sites More sharing options...
stevetimetravlr Posted January 19, 2012 Share Posted January 19, 2012 Even the most precision controlled castings and welds may still have flaws that only a x-ray can detect. So out of 10,000 biners how many may have a tiny void in the casting? We may never know as its not something that manufacturers like to give out info about. Quote Link to comment Share on other sites More sharing options...
B Deleted_Beck Posted January 20, 2012 Share Posted January 20, 2012 I'm sure all modern carabiners are forged to prevent that. Quote Link to comment Share on other sites More sharing options...
JosephH Posted January 20, 2012 Share Posted January 20, 2012 You can from the location of the failure and angle of the break that this was an open gate failure. Any other failure reason is extremely unlikely. How the gate opened is more the question. Quote Link to comment Share on other sites More sharing options...
tvashtarkatena Posted January 20, 2012 Share Posted January 20, 2012 Ya can't really tell shit from one crappy photo, but hey, I R un Enguneer n all that rot... Quote Link to comment Share on other sites More sharing options...
JosephH Posted January 20, 2012 Share Posted January 20, 2012 Sure you can, what don't you get from the location and direction of the break? Quote Link to comment Share on other sites More sharing options...
wetslide Posted January 20, 2012 Share Posted January 20, 2012 Last night I used an old biner to tow my car out of the ditch after a failed hill climb. Not sure what that lends to the conversation but I bet at least 4,000 lbs of force was exerted on it. That's not the first time I've used it for that task. Quote Link to comment Share on other sites More sharing options...
Kimmo Posted January 20, 2012 Share Posted January 20, 2012 One of my friends was slack-lining and had a carabiner snap. It was a fairly short line (no more than 30') and shouldn't have been under a huge load. Any thoughts...? first thought: never use such a flimsy piece of metal for slack-lining. second thought: the gate opened somehow. if i recall at all correctly, that biner has a gate that seems suspect in its ability to "lock" correctly. Quote Link to comment Share on other sites More sharing options...
JosephH Posted January 20, 2012 Share Posted January 20, 2012 Use a Fixe 50kn SS rap ring if you want to be absolutely sure of it. Quote Link to comment Share on other sites More sharing options...
tvashtarkatena Posted January 20, 2012 Share Posted January 20, 2012 Is it possible that the gate might have opened? Quote Link to comment Share on other sites More sharing options...
JeffreyR Posted January 21, 2012 Author Share Posted January 21, 2012 Is it possible that the gate might have opened? I was not present when it broke, but I do not see how it could have been pushed open by any of the line. It seems from the photo that it was the opposite end from the tensioner, but Iwould have to clarify with my friend. I imagine it would be possible that it never closed correctly before having a load put on it. Quote Link to comment Share on other sites More sharing options...
tvashtarkatena Posted January 21, 2012 Share Posted January 21, 2012 I was just messing whicha dood. I think about 20 people must have asked that same damn question here by now... Quote Link to comment Share on other sites More sharing options...
JosephH Posted January 21, 2012 Share Posted January 21, 2012 Either it somehow wasn't closed completely, or the closure keyhole lock failed from being a cheap piece of trash, or the gate opened under some unknown circumstance. I have seen a couple of strange, hard-to-account-for results with carabiners over the years. Once took a lead fall in CT on a steep overhang and the Chouinard 'D' biner on the piece below the one I fell on instantly shot out into space about twenty yards completely detached from both the rope AND the piece in the rock. I had double checked that placement and knew the biner was on good with the gate closed and oriented properly so go figure. Shit does occasionally happen which defies expectations, reason and logic if you didn't actually watch it happen. Quote Link to comment Share on other sites More sharing options...
genepires Posted January 21, 2012 Share Posted January 21, 2012 I R no enjuneer (I deal with electricity) but how about I throw out a theory for the failure. Biners are made to hold that limit of force (holding leader fall, whatever greater than 15kn) for a small period of time then quickly return to a couple KN's. Maybe between the possible harmonics (this is a great excuse for non engineers, always sounds plausible) and prolonged force applied to even a closed locking biner, was too much for it. Quote Link to comment Share on other sites More sharing options...
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