Ringling Bros. Accident

StradivariusBone said:

As an admirer of arena rigging and those who work in that field I was wondering where a carabiner would be used in a point? I wasn't aware of a rigging purpose of this device since it is so prevalent in rock/mountain climbing applications, I didn't even realize anyone made that particular hardware rated to that amount.

I'm not trying to get into speculation of this particular rigging scenario, I'm just curious on how it would fit into the equation, chain to spanset, stinger to chain, etc.? I thought they were primarily used with rope. I should also include I have no plans to do any sort of rigging involving this hardware, this aspect of our business is just fascinating to me. That being said, I respect the gravity of the situation and the wishes relayed through the aforementioned post. If my question is out of line, please let me know.

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Strad - I believe the ANSI standard for the typical climbing carabiner requires labeling MBS in kN or pounds - but that is not a statutory law, just a standard that meets the ANSI requirements for their designation. It seems the ANSI fall protection standards require same, but I have not bought them - quite steep - nor read more than summaries which may mislead. So I'd say that yes, there is a "standard" that requires labeled devices and MBS, but not a law or governmental entity in this country that enforces that. (read my Protocol article on Codes vs Standards for more on this.)

I'm not sure there is a standard as clear for, say, a turnbuckle or shackle, but usually not too hard to find via Google. Crosby seems to use a design factor of 5 - so if its marked or shown in data to be a 1000 WLL, then its 5000 MBS. That's probably OK for a static condition - like a lot of dead hung - but theatre rigging that lifts - with the combination of dynamic loading, the "overhead" factor, and tradition - generally has a design factor of 8 or 10 - so that 1000 pound WLL turnbuckle is only 500.

Keep in mind that the structural framing of a building is probably designed using a factor of 3 and may be lower in some cases.

MNicolai said:

News stories floating around that the women involved have retained a lawyer, and while litigation is not currently pending, a thorough investigation on the women's behalf is underway. It's still uncertain that all of the women will walk again, and physical therapy is ongoing for most of them.

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Link to the News Story
http://www.bostonglobe.com/metro/20...-law-office/OHIigFvzEvb9PWYaNQMCzJ/story.html

People who build aerial rigging are accustomed to dealing with components from different industries. It's the nature of the work and there's nothing wrong with that. They just break everything down to MBS and settle on a unit of measure.

Crosby uses a 6:1 for shackle WLLs: http://www.thecrosbygroup.com/html/en/pdf/pgs/77.pdf

A concrete-anchor manufacturer's engineer once suggested (in writing) that I cut/shorten certain type epoxy anchors for an application, and linearally-interpolate a reduced ultimate strength. So if I shortened an eight-inch 10,000lb SWL anchor of that type to 4" to accomodate a 5-1/2" concrete casting, he would consider it a 5,000lb SWL anchor. But the manufacturer's SWL was based on 4:1. So for my purpose, the sawed-in-half anchor was 20,000lbs MBS, and 2,000 WLL. THIS WAS SPECIFIC TO MY MANUFACTURER, MY APPLICATION, AND MY TYPE OF ANCHOR.

The same system used 17,000lb MBS cordage with a splice developed for the project. It tested at 84% efficient for net 14,620lbs.

There's no good way for the cordage manufacturer to list a WLL, while Crosby can't stamp MBS and rely on construction workers to know and apply the correct design factor.

In the current issue of Protocol (Summer 2014, ppg. 22-25), Rocky Paulson has an excellent article on the questionable use of caribiners for overhead lifting. For those of you who ever consider rigging of any type, this is a good article. It goes to show that there is more to the story than just determining the strength when designing for multiple uses.

And also this, from this morning:

http://boston.cbslocal.com/2014/11/04/feds-propose-7k-fine-in-hair-hanging-circus-stunt/

OSHA posted a press release: https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=NEWS_RELEASES&p_id=26943

The citation itself is hear: https://www.osha.gov/ooc/citations/Feldfinalcitation.pdf

The statement sure makes it sound like one extra shackle (to join the pear rings and bring the carabiner into only major axis loading) would have made a world of difference.

Once again I'm shocked at how small the OSHA fines are. $7,000 is the maximum allowed by law. Ringling makes that in popcorn sales before a single show even starts.

gafftaper said:

Once again I'm shocked at how small the OSHA fines are. $7,000 is the maximum allowed by law. Ringling makes that in popcorn sales before a single show even starts.

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The fines are one thing, and I agree they are shockingly small. The other thing is that once you've attracted the attention of OSHA, their watchful gaze is hard to shake.


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While the fine is small, the real financial impact will come from all of the lawsuits from injured parties. With the OSHA ruling behind them I would think it would make those suits pretty easy wins.

Initial OSHA fines are small, but now they need to stay squeaky clean for a few years. Any minor infraction can now carry hefty fines for the next infraction during the probationary period.

ruinexplorer said:

Initial OSHA fines are small, but now they need to stay squeaky clean for a few years. Any minor infraction can now carry hefty fines for the next infraction during the probationary period.

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This. Repeat violations can easily run in to the tens of thousands and even well over the $100k mark in fines (and/or jail time).

porkchop said:

OSHA posted a press release: https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=NEWS_RELEASES&p_id=26943

The citation itself is hear: https://www.osha.gov/ooc/citations/Feldfinalcitation.pdf

The statement sure makes it sound like one extra shackle (to join the pear rings and bring the carabiner into only major axis loading) would have made a world of difference.

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While it may seem to solve the problem, it might introduce torsional loading by having three components inline with the carabiner. But I would still rather have seen that than loading it like a shackle

cmckeeman said:

While it may seem to solve the problem, it might introduce torsional loading by having three components inline with the carabiner. But I would still rather have seen that than loading it like a shackle

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I see what you did there, with your Rope Access thinking/training. Just off the top of my head as I sit here sans coffee, I wouldn't worry about the torsional loading in this setup. But I could be wrong.

Update: OSHA findings. How I missed this, I not know.

https://www.osha.gov/doc/engineering/2014_r_05.html

Conclusions

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1. The cause of the failure of the carabiner was the manner in which it was loaded, subjecting the carabiner to tri-axial loading in violation of industry practice and the instructions of the manufacturer. The carabiners are designed to be loaded in their major axes along the spine.
2. Feld Entertainment, Inc./Ringling Bros. and Barnum & Bailey acted in an imprudent manner to rig the entire metal frame supporting eight performers on two pear rings attached to a carabiner. As there was no redundancy in the system, when the carabiner failed due to triaxial loading, the entire frame with the performers attached fell to the ground.
3. There is no document available to indicate that the rigging supporting several performers was ever reviewed and checked by a professional engineer for its structural adequacy and performance. This was a serious flaw that led to the incident.
4. One of the means of abatement was to place the two pear rings in a shackle instead of a carabiner.

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This is the part that I was looking for. I never heard of not using a carabiner in that way. Very interesting. So OSHA has ruled Feld entertainment liable due to improper use of the hardware as well as not backup safety... It will be interesting as to what comes out of this for aerial acts.

DuckJordan said:

This is the part that I was looking for. I never heard of not using a carabiner in that way. Very interesting. So OSHA has ruled Feld entertainment liable due to improper use of the hardware as well as not backup safety... It will be interesting as to what comes out of this for aerial acts.

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As far as changes moving forward it's worth noting #4 where they say that using a shackle would be a means of abatement. To me that sounds like they're suggesting that if you used the shackle then hooked a carabiner between the shackle and the SWR you'd be fine because the load is between only two points in line with the major axis of a carabiner. That's a pretty simple and easy change to make to a system.
Also getting designs stamped by an engineer (#3) and then inspected to ensure proper assembly is becoming more and more the industry standard (at least here in Vegas) which hopefully will help reduce the frequency of these kinds of accidents in the future.

To Duck, do you mean you thought triaxial loading on a biner was acceptable? Just not sure of your comment.

To Porkchop - which the spell checker does not permit substituting workshop - I thought the report suggested replacing the biner that failed with two shackles instead. I suppose two biners could be added to make assembly easier/quicker.

I am surprised by lack of PE review. I don't let a rigger dead hang a curtain track without calculations or a drawing sealed by a PE. That to me is the most egregious action by Field, et al.

My reading of the full report is that carabiners as a general device are not designed for triaxial loading and that was what caused the failure. Shackles are designed for triaxial loading (that's exactly what happens when you bridle a point) so if you used a correctly oriented shackle for the necessary triaxial connection point, and then used a carabiner attached to that shackle for quick attachment meaning the load at the carabiner is between two points in line with the major axis then there should not have been an overload condition.

Unfortunately, one of the downsides of being a largely self-regulating industry is that significant portions of the industry can adopt a standard practice, but there are probably other companies that don't even know that the emerging practice is an option yet alone are willing to pay to adopt it. Hopefully PE stamps for life safety applications will continue to rapidly spread in our industry. It makes me feel better every time I get something back with a stamp on it.

ruinexplorer said:

Update: OSHA findings. How I missed this, I not know.

https://www.osha.gov/doc/engineering/2014_r_05.html

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I don't think you missed it. I just saw it last week. The important thing is that it's being seen.