Everyone knows redundancy is chief when building climbing anchors. However, I have seen several types of anchors that don't appear to be fully redundant due to a single ring providing the master point.
Why are these acceptable and safe anchors?
asked Dec 1, 2015 at 0:33
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6Because the single point of failure is dramatically higher than the expected peak loads.– ErikDec 1, 2015 at 1:48
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6Not every part of the system is expected to be redundant. The rope isn't redundant. The waist belt of your harness isn't redundant. We often tie in to an anchor using a non-redundant locking biner. I don't bother with redundancy when using a big, healthy, well-rooted tree as an anchor. In the case of these rings, they are very easy to inspect visually. That's different from a bolt, where I can't necessarily tell if the bolt is secure in the rock.– user2169Dec 1, 2015 at 1:58
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2@BenCrowell is right, that should be an answer– user2766Dec 1, 2015 at 8:33
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1@BenCrowell definitely, I think it's important to highlight the reasons why this specific component is trusted– Chris MendezDec 1, 2015 at 12:17
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@chris no matter what you do , climbing will never be 100% safe. These anchors are trusted because they have been extensively tested and certified by several industry standards authorities. If you are skeptical about the strongest pieces of protection in the sport, then I don't understand how you find confidence in any other price of gear.– ShemSegerDec 2, 2015 at 3:08
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2 Answers
I happen to know for a fact that the steel ring in those anchor set ups is rated to 50kN. That's as much as both hangers combined, they're only rated to 25kN each, which is still double the force any human body will ever be able to produce. The human body is rated to fail somewhere around 12kN which is the amount of force a 1,200kg (2645.5lbs) object would exert on you pelvis if it were resting on your hips. Getting run over by a Honda Civic will do just a little bit less damage to your body than 12kN will. This figure is why most climbing gear is rated to 24kN or 25kN, so they can meet that minimum safety standard of double the force they will ever have to withstand under normal use. Before that ring ever comes close to failing, both bolts will literally shear out the rock, which will most likely never happen. Those rings are the most bomb proof part of either of those anchors, they are the very last thing you need to be worried about.
answered Dec 1, 2015 at 3:26
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1Yes, ideally. And yet these rings, however strong, are welded and could be susceptible to the same failures as the chains Dec 2, 2015 at 1:52
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@chris I can confidently assure you that the ring is the very last of your concerns. Every component of those anchors will fail before the ring does, it is the strongest link. It is physically impossible to make that ring fail under normal and even some abnormal climbing conditions. The bolt will pull out of the rock long before any of the components of either of those anchors fail. Dec 2, 2015 at 2:55
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1Keep in mind you should still inspect the ring for wear & tear before trusting your life to it.– FelixDec 4, 2015 at 11:50
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1@Felix Good point! If someone has been top-roping and lowering off the ring directly all bets are off. Feb 1, 2016 at 6:40
The answer is: these single point anchors are acceptable when new, and in perfect condition. After they have been misused by climbers lowering and belaying through them, these non-repairable anchors are not acceptable. They WILL be eroded by climbers lowering from grit covered ropes. Don’t kid yourself into thinking otherwise. Every climbing anchor is subject to this problem. That is why EVERY climbing top anchor should be redundant and have replaceable rope bearing components. These single point anchors are unacceptable.
