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Steel Carabiner Failure to Blame for RI Circus Accident
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By jim.dangle
May 6, 2014
Thought climbers might be interested in this:

boston.com/news/local/rhode-is...

Jim

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By Miike
From MA/CT border
May 6, 2014
my foot
Chinese made I bet.

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By David Peterson
May 6, 2014
Amarillo Sunset
Not sure how reliable the source of this picture is...

link
link

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By TKeagle
From Eagle, CO
May 6, 2014
redundancy anyone?

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By FrankPS
From Atascadero, CA
May 6, 2014
Should have used a Gri Gri. And a PAS.

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By rock_fencer
From Columbia, SC
May 6, 2014
Myself placing a a blue/yellow offset MC to protec...
Redundancy was the first thing that came into my mind. I went to an aerial show recently and they only had one biner holding up two people...plenty strong but surprised me none the less.

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By Max Forbes
From Burlington, VT
May 6, 2014
I was about to post this to see if anyone had more info. In regards to that picture above.. I've seen several reports now that described it as a "D" shaped steel carabiner but at this point I'm not really sure if anyone actually knows. Regardless its a sad situation, hopefully more info becomes available about what happens so that no one else makes the same mistake..

EDIT:

"The 5-inch long ring, which has three solid sides and one side with a spring-loaded and self-locking gate, was supposed to be able to hold 10,000 pounds."

nbcnews.com/storyline/circus-a...

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By Keithb00ne
From Las Vegas, NV
May 6, 2014
Grand Teton
"The aerialists suspended by their hair"

Hopefully they conditioned!

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By Mark NH
May 6, 2014
Local news reports in New England said that the carabiner failed on the non-opening side. So I wonder if it was cross loaded somehow and what that axial strength rating was (they did say 10K as has been posted).

However as I think we've all thought - only one attachment point! I would have certainly thought there'd have been redundancy.

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By Brian Scoggins
From Eugene, OR
May 6, 2014
The only reason climbers have such an enduring obsession with redundancy is that our gear is made so light that its necessary.

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By patto
May 6, 2014
Brian Scoggins wrote:
The only reason climbers have such an enduring obsession with redundancy is that our gear is made so light that its necessary.


That is not true. Our gear is MORE than strong enough that redundancy is not required from a strength point of view.

Furthermore most of the time in climbing we aren't using redundancy. Unless of course you are using two ropes, two harnesses, two belay device etc...

This "enduring obsession with redundancy" is hardly enduring nor an obsession. The only place where redundancy is consistently used is end of pitch anchors and rap points.

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By Brian Scoggins
From Eugene, OR
May 6, 2014
I was poking fun at the fact that people will, to this day, question the use of the belay loop, insist on opposed lockers for their connection to an anchor that's right in front of them, back-up enormous trees, etc. etc.

There is a great mass of climbers who believe that the first law of safety is redundancy and end up carrying twice as much crap as they need to because they compare the stated breaking strength of their gear with the safe working loads of industrial applications, and conclude that the latter is a more realistic standard.

In context, I wanted to emphasize that if you used aluminum carabiners in a trapeze act, you should definitely build in some redundancy, but the poor folks in this accident were using steel. The absence of redundancy did not cause this accident, nor should we as climbers interpret this as justification for hand-wringing redundancy-for-redundancy's-sake.

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By Craig Childre
From Lubbock, Texas
May 6, 2014
Potrero Mexico, Sport Climbing Mecca.
Reminds me of the guy who'd organize these big pendlem swings using steel cable on the Florida Key bridges. He got like 8 or 10 to swing with him. Added up their weight... plus a little extra for safety sake, and went out and purchased cable of suitable strength. Two of the swingers bailed before the event, and so they were overall lighter. He neglected to calculate how centrifugal force that magnified their weight. Lucky, the cable snapped near their low point. Impact was sufficient, that one wasn't breathing till the recessitate them on the pick up boat. Broken backs, arms and legs... it was ugly...

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By 20 kN
Administrator
From Hawaii
May 6, 2014
They probably should have used a shackle for that much weight. Shackles are far more suited for high loads than any form of carabiner.

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By doak
From boulder, co
May 6, 2014
Drinking with Moses
It occurred to me too that shackles might have been a better choice.

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By Bryan Ferguson
From Castle Rock
May 6, 2014
Marvin and Greg scoping Crow's Heads Spires - snow...
community.simplycircus.com/tut...

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By Chris D
From the couch
May 6, 2014
Sign near the Third Flatiron
From the above link:

4.5 Toughening up the Skin

Aerialists need to develop tough skin. The following are common suggestions for toughening up the skin:

  • The sandpaper method. Rubbing your hands with sandpaper daily or every other day basis works well.
  • Tincture of Benzoin. Available from any running supply house, this is known to toughen up skin, and it acts as an adhesive for keeping bandages on
  • Cramer's "Tuff Skin" spray is also know to toughen up the skin (and provide extra grip). It is available from various medical supply companies.
  • Urine. The acidity of the yellow stuff will help toughen up your hands.
  • Diluted white vinegar. Same effect as the yellow stuff, but without the associated germs, smells and general yuck factor.


I can see the product line for climbers now...

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By Dylan B.
May 6, 2014
Orgasm Direct, Devil's Lake, 5.11a  c. 2008
Brian Scoggins wrote:
I was poking fun at the fact that people will, to this day, question the use of the belay loop, insist on opposed lockers for their connection to an anchor that's right in front of them, back-up enormous trees, etc. etc. There is a great mass of climbers who believe that the first law of safety is redundancy and end up carrying twice as much crap as they need to because they compare the stated breaking strength of their gear with the safe working loads of industrial applications, and conclude that the latter is a more realistic standard. In context, I wanted to emphasize that if you used aluminum carabiners in a trapeze act, you should definitely build in some redundancy, but the poor folks in this accident were using steel. The absence of redundancy did not cause this accident, nor should we as climbers interpret this as justification for hand-wringing redundancy-for-redundancy's-sake.


Redundancy can prevent accidents; the lack thereof does not cause them.

redundancy |riˈdəndənsē|
noun ( pl. -cies)

Engineering. the inclusion of extra components that are not strictly necessary to functioning, in case of failure in other components : a high degree of redundancy is built into the machinery installation.

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By patto
May 7, 2014
Redundancy is one approach to increase safety in the event of failure.

When it comes to structural engineering though, the use of redundancy is not commonplace. More common is stringent quality control and understanding of materials used as well as a significant degree of difference between the design load and the design capacity. (AKA safety factor)

I would suggest both of these were lacking in this case.

A 50kN carabiner does not in my mind provide a sufficient safety factor.

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By Eliot Augusto
From Boulder, CO
May 7, 2014
I don't see why it would be so hard to run a second cable an inch or so longer, and have it connected at the same place. Bind both together with some cable clamps and have them run off of different devices at the top. 1 extra motion for the performers, and like $250 for the circus.

Hindsight is 20/20 though, and I probably wouldn't have thought to back it up seeing as how it's a tried and tested act.

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By ViperScale
May 7, 2014
Redundancy is more for pieces of gear that you don't have complete trust in. You rarely have complete redundancy but it is nice to have as much as possible.

You didn't put the anchor bolts in you don't know when they could fail. You don't want a trad anchor with a single piece that could pop.

However like others have said you still have only 1 point of failure normally and that is your rope.

Some places i climb their anchors are a ton of slings rapped around a weak tree and a rock. Not really the best feeling anchor in the world because these slings stay outside forever but there are about 3-4 around a rock and 3-4 around the small tree and 2 ovals balancing them so you would have to have a ton of them fail for your rap to go bad. I have at least once left my own sling (probably why there are so many) because all the ones there were that bad i didn't trust them.

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By Sean McAuley
May 7, 2014
patto wrote:
Redundancy is one approach to increase safety in the event of failure. When it comes to structural engineering though, the use of redundancy is not commonplace. More common is stringent quality control and understanding of materials used as well as a significant degree of difference between the design load and the design capacity. (AKA safety factor) I would suggest both of these were lacking in this case. A 50kN carabiner does not in my mind provide a sufficient safety factor.


Huh? Apparently every known bridge and building code is wrong then. Anything non-redundant is usually fracture critical, and taken heavily into consideration during design.

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By JSH
Administrator
May 7, 2014
JSH @ home  photo courtesy of Gabe Ostriker
Redundancy is a principle of engineering. Often, because many unknowing, trusting lives are at stake. This circus act should have been approached as an engineering problem, regardless of its use of climbing equipment. Redundancy fail.

Redundancy in climbing is a component, most often of anchors, but not as a general principle: as climbers, we each knowingly choose the risk. If there is a baseline principle, think of self-reliance, or 'the leader shall not fall'.

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By Tom Sherman
From Bristol, RI
May 7, 2014
John Sherman
W/ some structural engineering knowledge... and the numbers tossed above...
1,500 : 10,000 = Safety Factor of 6.667

With 9 performers, who i'm not sure travel with the show and weights are a constant variable, 9*150=1,350. And the structure above which is easily 10' in radius, the actual load had to be much more than 1,500 lbs.

That much mass, not rigidly supported would be subject to torsion. Although I don't have any knowledge of torque, or the mass' distribution in that structure. The inevitable torque created by not stabilizing that structure would be resisted by that cable above, ultimately resulting in a shear force in the cross section of the carabiner. This force easily multiplies the shear force created from the axial loading of the mass.

Lastly the movement of the acrobats, in-sync, would multiply this mass, similar to force exerted by the fall of the climber. In structural engineering, this force is called dynamic force. This force would also multiply the stated mass above.

It is easy to see that if a single carabiner rated for 10,000 lbs were used. The factor of safety for this setup would actually be much smaller than 6:1.

They should have backed it up, simple. But with more rigging above, it may have killed the illusion that the acrobats were 'flying in the air'.

How did I do? Any real engineers want to take a stab at it.

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By Buff Johnson
May 7, 2014
smiley face
either someone is full of shit on the initial report, or fatigued equipment wasn't tracked and pulled from service.

redundancy won't save you.

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By patto
May 7, 2014
Sean McAuley wrote:
Huh? Apparently every known bridge and building code is wrong then. Anything non-redundant is usually fracture critical, and taken heavily into consideration during design.


Key structural components of bridge/buildings are rarely REDUNDANT. Please understand the definition of redundant! (look it up if you have to).

For something to be redundant, for example a column, then you should be able to remove that item and have no effect on the structure or its operation.

JSH wrote:
Redundancy is a principle of engineering. Often, because many unknowing, trusting lives are at stake. This circus act should have been approached as an engineering problem, regardless of its use of climbing equipment. Redundancy fail.


Lack of redundancy is not the problem here nor is it the best solution.


Tom Sherman wrote:
How did I do? Any real engineers want to take a stab at it.

I'm a structural engineer.

What you said makes sense. Though rather than a redundant shackle. The best idea is simply to use a stronger shackle from reputable rigging supplier.

(I agree that 10,000lb is insufficient. Though i doubt i broke at 10,000lb. It was either cross loaded OR of suspect origin.

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