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slidingmike


Jan 31, 2012, 4:25 PM
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Beware using doubled wiregate biners in anchor
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Two opposite & opposing non-locking carabiners are as good as a locker in an anchor, right? (And yeah, it's probably better, since you're not relying on one point of failure.) Yet...

I saw an alarming sight recently when climbing up to an anchor my partner had built. He had used three opposite & opposing wiregate ovals, and as I got to the top and loaded the anchor, I saw all three gates slowly ease open. The master point was hanging freely and not leveraging on anything but itself.

I was able to reproduce this at home with both two and three carabiner configurations. Whether the gates pop open depends on how the carabiners are sitting next to each other at the time they are loaded.

I'll focus on the 2 biner case.

The first picture shows a 2-carabiner master point, with the biners sitting in a good position. Loaded or unloaded, the ovals don't move relative to each other and the gates stay closed.


The second picture shows the same anchor, but the carabiners have been slightly jostled and are still sitting perfectly opposite & opposing, but slightly offset.


The third picture shows what happens when the anchor above is loaded; the carabiners slide against each other as they try to line up and reach steady state. Unfortunately, the carabiner bodies are narrower than the gates, and as they slide past each other the gates get caught on the spines of the opposing biner. The result is that the fixed end of the gate doesn't move, but the mouth end of the gate moves, opening the gates.


I'm sure this has been observed before, and probably discussed here, but I've never seen it and wanted to raise the visibility. Clearly the open state of the biners reduces the strength of the anchor considerably.

Thoughts?


6pacfershur


Jan 31, 2012, 4:44 PM
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Re: [slidingmike] Beware using doubled wiregate biners in anchor [In reply to]
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that is just plain wicked!


bearbreeder


Jan 31, 2012, 5:07 PM
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Re: [slidingmike] Beware using doubled wiregate biners in anchor [In reply to]
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im generally fine with using 2 opposed non locking biners or draws ... thats what they use in the gyms around here as well

that said ... about a month ago i set up an anchor with 2 opposed draws and after some top roping one of the biners somehow clipped into one of the other biners and was in danger of getting unclipped ... no one would have died since it was caught and there would have been one good draw regardless

i have never had this happen before

ive been moving away from using 2 opposed draws from TR setups that will be used for the entire day unless the placements are perfect ... that is the spacing and height between the draws are textbook ... often youll find bolts that are staggered, places where the rock can bacng across the biners, etc ...

at the end of the day its a judgement call ... my preference is that should i be responsible for others safety, that i use something a bit more robust ... especially if you have TR tough guys doing flying traverses and assisted dynos ... im generally fine with 2 opposed on sport routes when the chains allow you to place the draws at the perfect height/stagger and its just for lowering/cleaning

note i believe the guiding standard and john longs book recommends 3 opposed non locking biners for "safety" ... or 2 opposed lockers ...

im sure certain RCers will come out of the woodwork now bashing me for using something more than 2 opposed draws Tongue


dead_horse_flats


Jan 31, 2012, 6:48 PM
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Re: [slidingmike] Beware using doubled wiregate biners in anchor [In reply to]
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Obviously this is a less than perfect situation, but what are the chances of actual failure?

Not zero but damned near.

I challenge anyone to provide a scenario that doesnt include an SFM* where failure could occur with this setup.

*Such as a cow falling out of the sky and landing on the anchor.


Partner xtrmecat


Jan 31, 2012, 6:48 PM
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Re: [slidingmike] Beware using doubled wiregate biners in anchor [In reply to]
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  If I recall history of wire gates correctly, they were brought to us out of a need to lighten a gate because of flutter caused by a rope when falling pulls the slack out. Traditional gates would vibrate and open their gates, slightly or completely.

I do not know any sound reason anyone would want to go away from a locker in an anchor. Two opposed biners to replace a locker would be secondary to the real thing. Like if you ran out of lockers. I do not know why many try to cut the safety corners.

Mentoring used to be the way we learned, from an old climber, and that practice is not the norm any longer. Books and internet learning are OK, but not nearly the quality of an old hand. Learning these things from any old Joe at the gym, or even crag for that matter is just plain nonsense, yet I see a whole pile of folks doing just that. Rant over.

To get back to the original issue, I am not at all surprised. Wire gates are not anchor material. Do they end up there? Sometimes we make do with what we have. I cannot think of any solid reasoning for intentionally making an anchor out of them, especially when a good locker is less than double the cost, only slightly heavier, and not prone to gate opening issues. Heck, I even see a pile of folks using lockers incorrectly, like they haven't a clue. It's your life, so carry on as you wish. Someone has to be the statistics.

Burly Bob


guangzhou


Jan 31, 2012, 7:08 PM
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Re: [xtrmecat] Beware using doubled wiregate biners in anchor [In reply to]
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I can't remember the last time I used two lockers at a master point for a top-rope. I tend to use two opposite and opposed binners. If I have them, I prefer ovals.

When I take groups out, I used three carabiners at the master point to increase the surface area a bit, but doesn't make the sytem any safer.

I understand lockers on bolt hanger for sure. I've never set up a top-rope with a single locker at the master-point. When I climb Multi-pitch, I do hang from a clove-hitch on a single locking binner on the master-point often. Sometime, I use even hang on clove-hitch on non-locker, but I do what I can to avoid this.


dead_horse_flats


Jan 31, 2012, 7:18 PM
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Re: [xtrmecat] Beware using doubled wiregate biners in anchor [In reply to]
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When has anyone ever experienced an anchor failure using two opposed non locking biners.

I will mail you a 20 bill the instant you can prove any remote possibility of this.

Common sense only please. No theories will be accepted.


Actually let me one-up that. Make an anchor with two opposed non-locking biners and with any means* excluding manually holding both biners open, demonstrate a method for the rope to escape both biners and I will mail you $40.

*I wont accept wrapping the rope around the biners either unless you can include a realistic scenario where this could happen unintentionally.


As far as two biners experiencing structural failure from the reduced strength of having both gates open - how, when, where? Where's the common sense here?


(This post was edited by dead_horse_flats on Jan 31, 2012, 8:04 PM)


slidingmike


Jan 31, 2012, 9:56 PM
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Re: [dead_horse_flats] Beware using doubled wiregate biners in anchor [In reply to]
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I think the point is not that the rope may escape, but rather that the strength of your anchor is dropped considerably (open gate rating x2 assuming the rest of the anchor is higher). Really, this kind of anchor would most likely be found in a toprope scenario, where the fall forces are unlikely to exceed that. But it certainly reinforces to me that lockers are a much better choice.


verticon


Feb 1, 2012, 2:48 AM
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Re: [slidingmike] Beware using doubled wiregate biners in anchor [In reply to]
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You should change the title to "Beware using doubled symmetric wiregate biners in anchor", but even so, 2 times 7 kN (for a BD Oval) = 14 kN, which in a need is pretty enough


healyje


Feb 1, 2012, 6:22 AM
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Re: [slidingmike] Beware using doubled wiregate biners in anchor [In reply to]
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The take away from that is all biners are not created equal - each design has its trade-offs. Pick the right biner for the job at hand and this design clearly shouldn't be used for this purpose.


Partner j_ung


Feb 1, 2012, 12:39 PM
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Re: [dead_horse_flats] Beware using doubled wiregate biners in anchor [In reply to]
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dead_horse_flats wrote:
When has anyone ever experienced an anchor failure using two opposed non locking biners.

I will mail you a 20 bill the instant you can prove any remote possibility of this.

Common sense only please. No theories will be accepted.


Actually let me one-up that. Make an anchor with two opposed non-locking biners and with any means* excluding manually holding both biners open, demonstrate a method for the rope to escape both biners and I will mail you $40.

*I wont accept wrapping the rope around the biners either unless you can include a realistic scenario where this could happen unintentionally.


As far as two biners experiencing structural failure from the reduced strength of having both gates open - how, when, where? Where's the common sense here?

I can't logically think of any toprope anchor that would fail if 3 of these things opened as described in the OP.

Doesn't exactly mean I'm going to switch to it, though.


herites


Feb 1, 2012, 3:38 PM
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Re: [slidingmike] Beware using doubled wiregate biners in anchor [In reply to]
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Why on Earth do you use oval wiregates for toproping? Toss in a locker and that's it. Also, I never understood why people insist on two lockers. The few things you should always trust are your harness, your rope and your biners (assuming you take good care of them) During toproping there's no chance that the biner will be crossloaded, also, if it's a locker you shouldn't care about it opening, so one is enough. Of course you can dream up a scenario where the stars align and you break a biner during toproping, but it's highly unlikely to happen in real life.


socalclimber


Feb 1, 2012, 3:51 PM
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Re: [xtrmecat] Beware using doubled wiregate biners in anchor [In reply to]
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"If I recall history of wire gates correctly, they were brought to us out of a need to lighten a gate because of flutter caused by a rope when falling pulls the slack out. Traditional gates would vibrate and open their gates, slightly or completely. "

Yup, simply put, use the right tool for the right job. Wire gates are not the right tool for this particular setup. I'll take two standard ovals over that setup any time.

If you prefer, substitute a locking oval.


majid_sabet


Feb 1, 2012, 3:59 PM
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Re: [slidingmike] Beware using doubled wiregate biners in anchor [In reply to]
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just use one locking biner and problem is solved.











but again, most climbers have a tendency to copy each other's bad habit.


socalclimber


Feb 1, 2012, 4:16 PM
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Re: [herites] Beware using doubled wiregate biners in anchor [In reply to]
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herites wrote:
Why on Earth do you use oval wiregates for toproping? Toss in a locker and that's it. Also, I never understood why people insist on two lockers. The few things you should always trust are your harness, your rope and your biners (assuming you take good care of them) During toproping there's no chance that the biner will be crossloaded, also, if it's a locker you shouldn't care about it opening, so one is enough. Of course you can dream up a scenario where the stars align and you break a biner during toproping, but it's highly unlikely to happen in real life.


Because two makes the rope run a bit smoother...


csproul


Feb 1, 2012, 4:40 PM
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Re: [herites] Beware using doubled wiregate biners in anchor [In reply to]
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herites wrote:
Why on Earth do you use oval wiregates for toproping? Toss in a locker and that's it. Also, I never understood why people insist on two lockers. The few things you should always trust are your harness, your rope and your biners (assuming you take good care of them) During toproping there's no chance that the biner will be crossloaded, also, if it's a locker you shouldn't care about it opening, so one is enough. Of course you can dream up a scenario where the stars align and you break a biner during toproping, but it's highly unlikely to happen in real life.
...And because lockers can and do come unlocked.


blondgecko
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Feb 1, 2012, 5:16 PM
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Re: [dead_horse_flats] Beware using doubled wiregate biners in anchor [In reply to]
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dead_horse_flats wrote:
When has anyone ever experienced an anchor failure using two opposed non locking biners.

I will mail you a 20 bill the instant you can prove any remote possibility of this.

Common sense only please. No theories will be accepted.


Actually let me one-up that. Make an anchor with two opposed non-locking biners and with any means* excluding manually holding both biners open, demonstrate a method for the rope to escape both biners and I will mail you $40.

*I wont accept wrapping the rope around the biners either unless you can include a realistic scenario where this could happen unintentionally.


As far as two biners experiencing structural failure from the reduced strength of having both gates open - how, when, where? Where's the common sense here?

I'll bite - sort of. I'm not going to attempt to win your bet, since I can't see this failing catastrophically. Given reasonably solidly-built climber and belayer (or solidly-built climber and a ground-anchored belay) repeatedly falling their way up something that requires leaving a bit of slack out, I can easily imagine the biners deforming enough so that they don't close properly - thereby becoming glorified keychains. With the gates open, plastic deformation can start to happen with surprisingly little force.

I found this little report from a student at MIT who tested a bunch of D-shaped biners to failure under cyclic loads, under both open- and closed-gate conditions. Unfortunately, for some reason he measured the deformation only of the closed-gate biners prior to failure, so the most interesting piece of information is missing imho.

Anyway, here's the rub: of the three biners he tested on a cyclic load of 0.5-6kN with their gates open, the strongest broke after just over 2,000 cycles. Even with the maximum load being just 4kN, they failed after 7,000-10,000 cycles. Now, that might still seem like a lot of force and a lot of cycles - but the thing is that the 2,000th cycle was just like the first - the only difference was the cumulative damage - creep, work-hardening etc. - done to the biner,. Who uses brand new biners every time they climb, and who uses their best, newest biners for toproping? Factor in some wear thinning out the metal near the spine, perhaps a bit of off-axis loading, and a bit of other "history" to the biner...

Me, I think I'll decide that discretion is the better part of valour, and avoid using wiregates for this application.


herites


Feb 2, 2012, 1:21 AM
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Re: [csproul] Beware using doubled wiregate biners in anchor [In reply to]
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Use a ball-lock biner then. Or do you say there's a real chance of that something presses the ball in, and at the same time, something twists the locking mechanicsm and then presses the gate so it gets stuck in open position? Don't chase ghosts and dream about one in a million what-ifs. You know, there's a chance that you'll get caught in an earthquake and whole crag (along with your doubled lockers) comes crashing down on you :)

The best solution in my opinion is, that crag developers should use an anchor which has a steel biner on the chains, not rap rings or w/e. Toproping is fairly common here and the biners are in a good shape, despite being installed years ago.


Partner j_ung


Feb 2, 2012, 2:34 AM
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Re: [herites] Beware using doubled wiregate biners in anchor [In reply to]
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herites wrote:
Why on Earth do you use oval wiregates for toproping? Toss in a locker and that's it. Also, I never understood why people insist on two lockers. The few things you should always trust are your harness, your rope and your biners (assuming you take good care of them) During toproping there's no chance that the biner will be crossloaded, also, if it's a locker you shouldn't care about it opening, so one is enough. Of course you can dream up a scenario where the stars align and you break a biner during toproping, but it's highly unlikely to happen in real life.

This is incorrect on a few points. Lockers can and do unlock quite often, including auto lockers. Biners can and do crossload during toproping, again quite often. Furthermore, toprope master points on long anchors rarely end up in a place of our choosing, and biners end up levered over edges and bulges--again quite often. I cant say why you've never seen any of those happen. How long have you been climbing?

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