Ringling Bros. Accident

[BillConnerFASTC]

I thought the problem with quicklinks was that you could not easily see by visual inspection if the were "closed" sufficient to assure their load rating, but in looking at manufacturers and distributors, clearly most state these are not to be used for overhead lifting.

 

[TuckerD]

Yes, and no.
Your proposed solution would eliminate the issue of tri-axial loading of a carabiner, but does not address the issue of using a product not actually rated for lifting. My interpretation of the OSHA report is that item #4 of the conclusions indicates not using carabiners in the load path.

I don't read it that way because there was another, mono-axial loaded carabiner (42kn) in the system and they didn't seem to criticize it's use.

How do you all feel about this 72kn carabiner? Could it / would you have used it in this scenario?

-Not a professional, asking questions and learning.

 

[gafftaper]

I thought the problem with quicklinks was that you could not easily see by visual inspection if the were "closed" sufficient to assure their load rating, but in looking at manufacturers and distributors, clearly most state these are not to be used for overhead lifting.

My previous gig was a small black box which had a miniature fly system. There were 12' battens scattered about between the catwalks overhead on an old school sandbag counterweight system. It was great for hanging a banner or flying in a chandelier in a play. The battens were hung with batten clamps then a quick link tied on a rope. They were Chinese made and "rated" at 500lbs. Jay Glerum told me to replace them with Shackles. He told me his objection was that it's broken circle and the only thing keeping it from failing were the threads of the screw section... given that mine were Chinese made that was even more scary. At the time I think there was only one brand of non-Chinese properly rated quick links in the world. So perhaps the Chinese factor was what led to the concern about the threads failing. I didn't ask about swaping for rated quick links as I doubt I knew if they even existed and just putting in shackles was relatively inexpensive and easy to do.

Not a professional, asking questions and learning.

It's rare to have a rigging discussion here on CB that it's safe to really get in deep and discuss. I love it when it happens because we can all learn so much from these guys.

 

[BillConnerFASTC]

My previous gig was a small black box which had a miniature fly system. There were 12' battens scattered about between the catwalks overhead on an old school sandbag counterweight system. It was great for hanging a banner or flying in a chandelier in a play. The battens were hung with batten clamps then a quick link tied on a rope. They were Chinese made and "rated" at 500lbs. Jay Glerum told me to replace them with Shackles. He told me his objection was that it's broken circle and the only thing keeping it from failing were the threads of the screw section... given that mine were Chinese made that was even more scary. At the time I think there was only one brand of non-Chinese properly rated quick links in the world. So perhaps the Chinese factor was what led to the concern about the threads failing. I didn't ask about swaping for rated quick links as I doubt I knew if they even existed and just putting in shackles was relatively inexpensive and easy to do.


It's rare to have a rigging discussion here on CB that it's safe to really get in deep and discuss. I love it when it happens because we can all learn so much from these guys.

Most rigging is held up by threaded fasteners, so not sure I think all things threaded are bad. In googling these, I did find someone - a climber - who tested a batch and some failed well below their SWL. A batch from another far east country did fine. In the end, not rated for overhead lifting is enough for me.

 

[egilson1]

My previous gig was a small black box which had a miniature fly system. There were 12' battens scattered about between the catwalks overhead on an old school sandbag counterweight system. It was great for hanging a banner or flying in a chandelier in a play. The battens were hung with batten clamps then a quick link tied on a rope. They were Chinese made and "rated" at 500lbs. Jay Glerum told me to replace them with Shackles. He told me his objection was that it's broken circle and the only thing keeping it from failing were the threads of the screw section... given that mine were Chinese made that was even more scary. At the time I think there was only one brand of non-Chinese properly rated quick links in the world. So perhaps the Chinese factor was what led to the concern about the threads failing. I didn't ask about swaping for rated quick links as I doubt I knew if they even existed and just putting in shackles was relatively inexpensive and easy to do.


It's rare to have a rigging discussion here on CB that it's safe to really get in deep and discuss. I love it when it happens because we can all learn so much from these guys.

Harry Donovan use to do this thing when you asked him a question where he would listen to you, then tilt his head up look at the ceiling, think and then proceed to try and give you an answer. Half the time, it wasn't actually an answer. I learned that what he was doing when he was looking up was debating the liability that could potentially fall on him if he answered the question. I find myself doing this more and more as I age. When I started Entertainment Rigging Sessions after Rocky urged me to do so, I specifically made a mental note to work as hard as possible to give people usable advice and answers. Sometimes that means a bit of effort and research, and of course time. I can tell you my response yesterday was 2 days of thought, and a hour of typing before I posted all of what, 3 paragraphs? But it's important to help educate our community.

Ethan

 

[egilson1]

I don't read it that way because there was another, mono-axial loaded carabiner (42kn) in the system and they didn't seem to criticize it's use.

How do you all feel about this 72kn carabiner? Could it / would you have used it in this scenario?

-Not a professional, asking questions and learning.

I would as a general practice not use equipment that has only a breaking strength and no working load limit without a written and accepted standard of what an appropriate design factor should be for that piece of hardware and it's use.

On this particular carbiner, I do like the fact that they proof test it. And if I could get some more data on that proof testing from the manufacture it could be something I would consider using.

Ethan

 

[porkchop]

My understanding on Jay's thoughts of the use of quick links was at one point in time, finding load rated quick links was almost impossible. Add to that the idea that a quick link has an "up" and "Down" orientation that often is missed, leading to potential opening. We have been having a discussion on the "Statically suspended rigging" task group about the use of non-closed looped hardware. E.G. bent eye-bolts. One person brought up the point that if it's properly rated for the load, why is it not appropriate? if you overload a piece of hardware, regardless of its design, it's going to fail is it not? This of course ignores the idea of capturing the load in an seismic event, which to me is a must have and part of the standard.

I realize the answer i gave may create more questions than it actual answered.

Ethan

The other issue with quick links, assuming you can find one that is actually rated, is that rating only applies if the nut is fully seated and if it backs off at all then it's load bearing capacity is reduced by some indeterminate amount. It's easy to mouse a shackle, an ANSI 359z carabiner has a spring pushing the gate into it's locked position, but it's relatively more difficult to keep a quick link fully closed.

 

[What Rigger?]

Currently going through all the growing pains of educating a lot of the crew on my gig, or reminding them if you will, about when/where/what/how to lift gear vs how to lift (or have climb )people. It's a heck of a thing. Ethan brings up many valid points a lot of people totally miss regarding choice of gear and what is warranted for what.

 

[derekleffew]

Currently going through all the growing pains of educating a lot of the crew on my gig,

Simple, really.