Titanium Bolt Failure.

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Messages 21 - 40 of total 199 in this topic << First  |  < Previous  |  Show All  |  Next >  |  Last >>
drgonzo

Trad climber
east bay, CA
Aug 4, 2008 - 03:10pm PT
people would clip it and hang and twist on it (this went on for years and frequently they say) while they figured out the crux to get out the roof.

"People?!?!?" More like freakin' hangdog sporty boys... ;-)
dirtineye

Trad climber
the south
Aug 4, 2008 - 03:14pm PT
Sport climbers are people too.... well sort of.
the kid

Trad climber
fayetteville, wv
Aug 4, 2008 - 03:18pm PT
this looks like a standard weld shut to me..
Here at the new river gorge, when we use glue in's they are petzl stainless steel units.. i would take stainless over ti any day..
ks
Hardman Knott

Gym climber
Muir Woods National Monument, Mill Valley, Ca
Aug 4, 2008 - 03:18pm PT
All the discussion of metallurgy and sport-dogging is interesting, but is completely irrelevant to this case.

Take another look, and please explain WTF is going on here:



There's no question that that is an improperly placed bolt (assuming that that bolt was actually placed somewhere).

Failing an explanation, I'm inclined to suspect that this whole story is a Bullshít Troll™ (or part of a smear-campaign against
Ushba). I'd love to hear from the person who actually "placed" that bolt, but I'm knott holding my breath...

locker

Trad climber
Joshua Tree Ca
Aug 4, 2008 - 03:21pm PT
I THINK you are on to something HK...

Greg Barnes

climber
Aug 4, 2008 - 03:28pm PT
Kurt, any day except when you're climbing in warm seaside environments, I hope? I've seen glue-ins broken off at the surface of the rock in Thailand, and Petzl folks went down there years ago to confirm that stainless steel bolts were shattering within only a few years. The exact mechanism is still being investigated, so there's a slight chance that you could see similar results with stainless steel in non-seaside warm environments if there are just the right chemicals present. http://www.safeclimbing.org/education/deepbluesea.htm

Both the Petzl and the Ushba 10mm glue-ins are rated to 25kN, so unless you're using the giant Petzl glue-ins (14mm, 50kN), they should be the same strength.

That picture sure looks weird. I can't imagine any scenario that would result in the bolt breaking deep in the hole with a bend, since it shouldn't be possible to break through the epoxy and the rock to that depth on a properly installed glue-in.
stich

Trad climber
Colorado Springs, Colorado
Aug 4, 2008 - 03:30pm PT
I know the principles in the original discussion personally, Knott, so it's not a troll. I remember when they placed those glue-ins.
Hardman Knott

Gym climber
Muir Woods National Monument, Mill Valley, Ca
Aug 4, 2008 - 03:46pm PT
Thanks for clearing that up. I think it goes without saying that "properly placed" includes
placing the bolt in suitable rock, since crumbling rock is the only thing that makes sense.

But even then, I simply can't picture the bolt bending to that extent, that far from the eye,
knott to mention the bolt bending in the wrong direction. So again I ask, WTF?




klk

Trad climber
cali
Aug 4, 2008 - 04:09pm PT
Well, if the bolt as originally placed could pass visual inspection, one possible scenario is that the soft rock at the surface gradually eroded away as folks twisted and dangled on that bolt. (Thus providing the weird angle stresses that the op describes.) Then the snap line would represent that place where the rock was just good enough not to pulverize under that sort of stress. In that case, the bolt before it broke would've looked pretty manky-- a chossy, fracture scoop around the eye, some of the shaft probably visible. I have seen bolts that bad in serious choss.


Hardman Knott

Gym climber
Muir Woods National Monument, Mill Valley, Ca
Aug 4, 2008 - 04:12pm PT
To my mind, if the bolt was properly oriented, the loop itself would be resting against the rock,
and even if the rock inside crumbled, the rock outside would support it and prevent bending.

That is why I suspect it was placed upside down, or in a manner so that it was opposite to the direction of loading.
scuffy b

climber
Zeno's Paradise
Aug 4, 2008 - 04:22pm PT
Placed in a roof, HK.
This explains the direction of bend.
Hardman Knott

Gym climber
Muir Woods National Monument, Mill Valley, Ca
Aug 4, 2008 - 04:23pm PT
So how would the bolt be loaded if it was rotated 180 degrees?
klk

Trad climber
cali
Aug 4, 2008 - 04:24pm PT
Maybe I wasn't clear-- it was placed upward into a roof (unless I read incorrectly) made of complete choss. So when folks dangled and spun, the surface rock gradually broke and eroded away, exposing part of the shaft. The better rock didn't erode, thereby creating a fulcrum line right, which is where it sheared. One would have to have rock so crummy that you could crunch away the surface with not much more than a fingernail scraping at it, but from the quotes, it sounds like that's the scene there. I'm not crazy about this scenario, but can't think of a likelier one.

I am presuming here that, if it had been fixed with the eye that far stuck out from the original surface, that someone would've said something.
dirtineye

Trad climber
the south
Aug 4, 2008 - 04:35pm PT
Must.. See.. Cross section!!! (choke) (gasp)
Brian in SLC

Social climber
Salt Lake City, UT
Aug 4, 2008 - 04:36pm PT
Would really like to see a cross section straight on photo of the break.

My bet is that if it was repeatedly dogged on, and it was originally placed so that part of the shaft of the bolt was in contact with the rock (or it got that way when the rock busted around it), then it eventually got a scratch/dent on it which bloomed into a stress riser. Fatigue then fast fracture failure when the crack became big enough to not withstand the load.

Er something like that.

Anyhoo, a good close up photograph of the surface of the busted area would be super revealing.

-Brian in SLC
Hardman Knott

Gym climber
Muir Woods National Monument, Mill Valley, Ca
Aug 4, 2008 - 04:37pm PT
I will Paypal $10.00 (the cost of 2 beers with tip) to the first person who posts close-up
pics of the hole of the broken bolt (alternately, they can be e-mailed to me).

The eye of the bolt should have been resting against the rock in the direction of force,
preventing the bending shown in the pic. If pics are knott too much trouble, beers on me!

Edit: Brian - we were composing our posts at the same time - LOL!
scuffy b

climber
Zeno's Paradise
Aug 4, 2008 - 05:35pm PT
"So how would the bolt be loaded if it was rotated 180 degrees?"

It would be loaded the same.
The bend is a result of loading in pull, not shear.
The bolt was placed in a roof, not near a roof, not before or
after a roof.
The direction of the bend is OK. The location of the bend, so
far from the eye, indicates soft rock or crappy hole.
bwancy1

Trad climber
Aug 4, 2008 - 05:46pm PT
Let me fix that for you...

The direction of the bend is OK. The location of the bend, so
far from the eye, indicates soft rock or crappy hole"


That makes sense to me too...
...or not being set deep enough.
JLP

Social climber
The internet
Aug 4, 2008 - 06:46pm PT
There appear to be no witness marks anywhere on the bolt. Assuming the bolt was photo'd sometime reasonably soon after the break, I would assume the thing was sticking out of it's hole up to near the "glue ring"

It looks like it broke pretty close to the first "glue ring" feature. The bolt "cross section" will be thinner here - significantly less strong. Depending on how the ring feature was manufactured into the bolt, there will certainly be additional stresses, the magnitude of which depend on the process.

I'm therefore concerned about the glue ring.

Sigma = My/I, I = pi r^4/4. Let's say the ring is 5cm dx from the load point, so 1kN force fall is 50 N-m @ break. Let's call the ID of the ring @ 5mm, so r = .0025 m. Solving, we get Sigma = ~8E10 Pa, not accounting for the additional stress imposed by the "glue ring" geometry and manf. process, and additional likely torsional stresses. Titanium Alloy snaps at 9E9 Pa. My numbers are guesses, but they show that it is certainly possible. Have fun speculating - or stick the real #'s in and see what you get.

Don't really need to see much else in the pic, just dimensions of a similar bolt. Looks like a design/installation issue to me - both. Direction of loading shouldn't matter beyond inducing torsion - ie, doesn't matter if they placed it upside down - sideways might matter more.

Lesson to self: bolts sticking out of rock = bad - these glue ins are probably best with the ring pointing down, seated against the rock and into some of the epoxy that oozes out of the hole.
healyje

Trad climber
Portland, Oregon
Aug 4, 2008 - 07:02pm PT
Notice how most bolts of this variety are best installed in a recessed manner as opposed to just drilling a hole and sticking it in.

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