# Triaxial Loading



## dvsDave (Aug 22, 2019)

*What is triaxial loading*: What does the term mean, where is it encountered and why is it often a concern? For bonus points: Explain how you'd circumvent the issue. 

*Students ONLY for 10 days.
*
Questions will be judged/commented on by @egilson1 and @What Rigger? 

Thanks to @RonHebbard for suggesting the question.


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## Lynnchesque (Aug 31, 2019)

My first guess was that this is some kind of exotic concept of electricity..
But now I am envisioning dangerous situations where truss buckles and boom lifts tip over.


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## josh88 (Sep 2, 2019)

Don't ask Ringling Brothers.


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## What Rigger? (Sep 2, 2019)

:shock:


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## eadler (Sep 5, 2019)

Clearly this is what happens when someone hangs a drop from a piece of triax camera cable.


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## RonHebbard (Sep 5, 2019)

eadler said:


> Clearly this is what happens when someone hangs a drop from a piece of triax camera cable.


 *@eadler* Oh you innovators inside your walls; What's the safe working load of your triax and what kind of knots do you use*??* ( Inquiring minds yada, yada. . . ) 
Toodleoo! 
Ron Hebbard


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## eadler (Sep 5, 2019)

I mean, Belden does spec a max recommended pulling tension of 124 lbs. I imagine the stranded version is higher... This is what we really have so 264 lbs of pull tension, give it a 10:1 safety factor and you can hang about 25 lbs from it without damage!
Oh, and always a bowline. 

(For anyone thinking this is serious - No. Don't. Please.)


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## JChenault (Sep 5, 2019)

Somehow this discussion reminds me when our tour u haul truck brok down and we towed it with a length of 12/3 SJ cable


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## RonHebbard (Sep 5, 2019)

eadler said:


> I mean, Belden does spec a max recommended pulling tension of 124 lbs. I imagine the stranded version is higher... This is what we really have so 264 lbs of pull tension, give it a 10:1 safety factor and you can hang about 25 lbs from it without damage!
> Oh, and always a bowline.
> 
> (For anyone thinking this is serious - No. Don't. Please.)


*Where's that Double LIKE button? 
@eadler * Thanks for your tongue in cheek reply, clearly better than coax with BNC's and FAR superior to solid coax with F connectors. 
*@What Rigger? @egilson1 @FMEng* and *@Ancient Engineer* Would you care to play along?? _PLEASE!!_
Toodleoo! 
Ron Hebbard


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## RonHebbard (Sep 5, 2019)

JChenault said:


> Somehow this discussion reminds me when our tour U haul truck broke down and we towed it with a length of 12/3 SJ cable


 Understood and appreciated. Did you by any _stretch_ employ two lengths of SJ and anchor them with ONE ( Singular ) carabiner*??* 
Toodleoo! 
Ron ( with my tongue so firmly in my cheek as to likely require surgical extraction. ) Hebbard


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## sk8rsdad (Sep 5, 2019)

eadler said:


> about 25 lbs from it without damage!
> Oh, and always a bowline.
> 
> (For anyone thinking this is serious - No. Don't. Please.)



Your math is wrong. A bowline reduces the strength (of rope) by about 1/3 so the maximum load would be about 16 lb or about 7 kg for every country other than the United States, Myanmar, and Liberia.


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## josh88 (Sep 6, 2019)

Since it's been enough time and nobody has answered, its 3 points of loading under tension, most problematic with a carabiner, (see the providence Ringling Brothers accident where a carabiner that was triaxially loaded broke, and dropped a bunch of people) though you can do it with shackles as well. In the case of the Ringling incident, they had 2 pear rings on a carabiner which caused it to break. The osha findings cited that a shackle would have abated that. With a carabiner, the strength is inline with the spine, so a triaxial load spread that out at an angle and therefore distribute the load in a way that lowers the overall strength of the carabiner and puts stress on it.

As far as I know, nobody recommends or says doing this with a carabiner is safe.


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## BillConnerFASTC (Sep 6, 2019)

It's a complicated issue so safe to say no, but I believe some common climbing situations require tri- and quad-axial loading.

shorturl.at/ehlzW

As this report shows, the ultimate strength of the triaxially loaded biner is less than when properly loaded in line with the spine, but not substantially.

Generally, I try not to rely on biners. Don't load a biner other than (bi)axially unless you really have done the work. And I think most of the time that work is finding the worst case impact. When it all goes fubar, what is that impact? Requires a lot of education and mentored experience to calculate that.


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## RonHebbard (Sep 6, 2019)

BillConnerFASTC said:


> It's a complicated issue so safe to say no, but I believe some common climbing situations require tri- and quad-axial loading. https://www.blackdiamondequipment.com/en_US/qc-lab-off-axis-tri-axial-carabiner-loading.html
> As this report shows, the ultimate strength of the triaxially loaded biner is less than when properly loaded in line with the spine, but not substantially.
> 
> Generally, I try not to rely on biners. Don't load a biner other than (bi)axially unless you really have done the work. And I think most of the time that work is finding the worst case impact. When it all goes fubar, what is that impact? Requires a lot of education and mentored experience to calculate that.


Uh, Bill? Your link's not working for me. 
Toodleoo! 
Ron Hebbard


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## RonHebbard (Sep 6, 2019)

RonHebbard said:


> Uh, Bill? Your link's not working for me.
> Toodleoo!
> Ron Hebbard


Prior to posting the current QOTD, @dvsDave included an excellent video in a PM. 
I'll try to cut 'n paste it but I may not be successful. @dvsDave could post it if my cut 'n paste is unsuccessful. 
I found a great video on triaxial loading done by Chicago Flyhouse, Inc!


_""Literature and fiction are two entirely different things. Literature is a luxury; fiction is a necessity. A work of art can hardly be too short, for its climax is its merit. A story can never be too long, for its conclusion is merely to be deplored."_
-G.K. Chesterton


Toodleoo! 
Ron Hebbard


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## BillConnerFASTC (Sep 6, 2019)

That should work.


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## RonHebbard (Sep 6, 2019)

BillConnerFASTC said:


> That should work.



On my screen (MS10 / Chrome), a message appears stating: "Control Booth error. Invalid Advertiser Id, Publisher Code, Offer, or Publisher - Advertiser Partnership Status" 
*@dvsDave* Help!? 
Toodleoo! 
Ron Hebbard


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## eadler (Sep 6, 2019)

sk8rsdad said:


> Your math is wrong. A bowline reduces the strength (of rope) by about 1/3 so the maximum load would be about 16 lb or about 7 kg for every country other than the United States, Myanmar, and Liberia.


To be fair, if I were to actually want to do this and have the cable come out usable, it'd probably be less than a pound of force before it pulled the cable tighter than the minimum bend radius with any knot or hitch (short of putting hitches around a 279.4mm or larger O.D. pipe). If I actually wanted to do this for loading and not care about the ~$10/m cable, I would go through the spec sheet and account for the breaking strength of the various insulation and jacket materials and likely find a much higher rating -- the maximum pull tension (1174.320 N) is a spec for maintaining the cable's ability to meet the specified electrical characteristics - essentially at this pull strength the cable will not deform (or will deform 'evenly' across all layers/insulations/dielectrics). 

Step one of course for this exercise is to place ones tongue firmly against a cheek.
Here's the metric spec sheet in case you want to do some real math


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## dvsDave (Sep 6, 2019)

RonHebbard said:


> On my screen (MS10 / Chrome), a message appears stating: "Control Booth error. Invalid Advertiser Id, Publisher Code, Offer, or Publisher - Advertiser Partnership Status"
> *@dvsDave* Help!?
> Toodleoo!
> Ron Hebbard



Shoot me a Private Message if you are still showing this error.


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## What Rigger? (Sep 6, 2019)

RonHebbard said:


> *Where's that Double LIKE button?
> @eadler * Thanks for your tongue in cheek reply, clearly better than coax with BNC's and FAR superior to solid coax with F connectors.
> *@What Rigger? @egilson1 @FMEng* and *@Ancient Engineer* Would you care to play along?? _PLEASE!!_
> Toodleoo!
> Ron Hebbard


Like I even know what triax cable is. I mean, I have the Google, but you can't expect me to look things up.


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## What Rigger? (Sep 6, 2019)

josh88 said:


> Since it's been enough time and nobody has answered, its 3 points of loading under tension, most problematic with a carabiner, (see the providence Ringling Brothers accident where a carabiner that was triaxially loaded broke, and dropped a bunch of people) though you can do it with shackles as well. In the case of the Ringling incident, they had 2 pear rings on a carabiner which caused it to break. The osha findings cited that a shackle would have abated that. With a carabiner, the strength is inline with the spine, so a triaxial load spread that out at an angle and therefore distribute the load in a way that lowers the overall strength of the carabiner and puts stress on it.
> 
> As far as I know, nobody recommends or says doing this with a carabiner is safe.


@josh88 and @RonHebbard and everybody else: sorry to be a bit of a ghost. We're on a big training compliance push around here. _Anyhoo….._
Josh pretty much nails it, and since I have a thing for Black Diamond gear, here's some great stuff regarding what triaxial loading is, what it does to carabiners (yep, it's baaaaad).
https://www.blackdiamondequipment.com/en_US/qc-lab-off-axis-tri-axial-carabiner-loading.html
From the page linked above:

*Bottom Line:*

"In general, climbing gear is pretty robust, but that statement holds more true when the gear is used as designed and in typical loading scenarios. Once you start to stray off from ideal use (ie. off-axis loading, tri-axial loading, quad-axis loading), then you can see the ultimate strength reduced, even to the point, as in a nose-hooked scenario, where things become super sketchy.

So the bottom line is that you need to keep carabiners lined up along the major axis and try not to allow for multi-directional loading of carabiners, because it compromises their strength. "


Now, as for where we encounter this:
Lots of times, in my own anecdotal experience, in recreational climbing scenarios. In other words, folks who just don't know.
In terms of business, and again in my own anecdotal (and what I've heard from other friends who work in the air), mostly with aerialists with little to no training- or just enough to be dangerous. Truly, want make yourself crazy? Go jump into the "aerialist safety" type groups on the Book of Face. We also see this with more inexperienced riggers trying to cram a whole lot of stuff into too little space.
Do some reading- manuals and catalogues and websites will tell you all kinds of stuff you never knew you never knew. (For those of you who have been around, you'll recognize the acronym: RTFM)

How do we mitigate this stuff? Training! Always share knowledge to make others better. But make SURE you know what you're talking about. If you can train nothing else, train people to say "stop" when there is question or doubt. Sometimes it's hard to train courage to people for things like this, but it's totally okay to raise a concern and find out your fears were unfounded. Know why? Because if you say nothing, and someone is injured/dies or millions of dollars of gear crash down- how you gonna feel about yourself after that?

Now, the rest of the mighty CB should jump in here and call out what I missed. Seriously, go!


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## BillConnerFASTC (Sep 6, 2019)

Something about black diamond site that makes it hard to link since both my link and what riggers don't work.

See if this works:. 

https://www.google.com/url?sa=t&sou...Vaw1WhsIPWvtuSF_-xCZCYC9V&cshid=1567809727726


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## BillConnerFASTC (Sep 6, 2019)

Does now. Not sure it will later.


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## What Rigger? (Sep 9, 2019)

Thanks, Bill! Somedays I just bang my head on the keyboard to see how many keys I can hit at once. Somedays I do actual things.
-Brian


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## BillConnerFASTC (Sep 9, 2019)

What Rigger? said:


> Thanks, Bill! Somedays I just bang my head on the keyboard to see how many keys I can hit at once. Somedays I do actual things.
> -Brian


That was a difficult link to cut and paste. It's like they tried to make to hard. Glad we both pointed to it. Strength in numbers. (Several puns therein)


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## TimMc (Sep 10, 2019)

At the risk of impersonating Captain Obviousman, isn't triaxial loading one use of a pear ring?


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## Michael K (Sep 11, 2019)

TimMc said:


> At the risk of impersonating Captain Obviousman, isn't triaxial loading one use of a pear ring?


To follow up Tim's question, what is/are the proper methods for situations that require tri/quad-axial loading? Should a shackle be used in place of the carabiner? Some sort of pear, round, or other shaped ring?


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## What Rigger? (Sep 13, 2019)

TimMc said:


> At the risk of impersonating Captain Obviousman, isn't triaxial loading one use of a pear ring?


Sure is. But pear rings are built for that. Carabiners, definitely not.

As for shackles, we're talking as in making legs to a shackle? Watch out for that bridle angle that you don't go past the capacity of the shackle.


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