[TR] Index Broken Bolt Hangers (Sport Wall) - Calling Wolfgang 8/23/2009

[Pete_H]

Climbed Tunnel Vision at the Country this weekend. The first three bolts are Kong Bonnati, they looked steel but anyone know for sure?

[billcoe]

Thanks Mark. I don't recall seeing many of these (I maybe never have seen one) yet. Can anyone else say if they are aware of this hanger being located on other routes or anyplace else?

 

Has anyone here besides Pete ever seen a Kong - Bonatti hanger before? I don't remember ever seeing one. (but I live a sheltered life:-)

 

Probably need to get some widespread reporting out there for other climbers in other areas to share the info and look for more hangers to verify condition of any still in play.

[Brian in SLC]

Has anyone here besides Pete ever seen a Kong - Bonatti hanger before? I don't remember ever seeing one.

 

I'll have to check my stock, but, I think I have some in both stainless and aluminum. I seem to recall they made stainless, aluminum and plated.

 

Crazy, but, it looked like aluminum to me. I've seen similar type corrosion on old, aluminum cave hangers (the old ones with the small, 1/4" inch hole and the eye oriented like a Petzl Coudee or a Lucky Alba). The one I saw was on a old (60's) route in Montana with rawl split shaft thread head bolts. Back side of the hanger had been "eatin'" out and was scaley, similar to the photo's of Kong hanger in question.

 

Crazy, and, frightening.

 

Cheers,

 

-Brian in SLC

[Brian in SLC]

Just swung the photo's by a metallurgist friend of mine. "Exfoliation corrosion".

 

"Corrosion products building up along grain boundaries exert pressure between the grains and the end result is a lifting or leafing effect. Aluminum alloys that have been extruded or otherwise worked heavily, with a microstructure of elongated, flattened grains, are particularly prone to this damage. The damage often initiates at end grains encountered in machined edges, holes or grooves and can subsequently progress through an entire section.

 

In this particular form of intergranular corrosion the expansive force of insoluble corrosion products tends to force the grains apart and leads to exfoliation corrosion, sometimes known as lamellar or layer corrosion. In extreme cases, the edges of the affected area are leaf like and resemble the separated pages of a wetted book that has become swollen and begun to open up."

 

Sounds like.

 

Surfin' around on the 'net, I wonder if the bolt material type, zinc plating, and certainly the environment (Index, pretty wet) all played a part.

 

I'm thinkin' 20 year old aluminum hangers in a wet environment just aren't meant to last that long. When did folks start placin' a bunch of bolts/hangers with power drills? Late 80's. How long ago was that? Yeah, 20 years ago.

 

Scary.

 

-Brian in SLC

[Buckaroo]

That hanger is definitely aluminum. It's massively corroded but not with ferrous rust. It has some slight ferrous rust staining, probably from a ferrous bolt nut or washer. Stainless will not corrode like that.

 

Aluminum can be identified by the sound it makes when tapped with another hard object. It's hard to explain you have to try it for yourself. Just tap it with a beaner. Once you get used to this ID method you can even tap with your fingernail. Try it, compare a beaner to a steel piton by tapping.

 

Aluminum can also be ID'd visually although this is not as certain when you start talking coatings.

 

Another clue might be thickness, would imagine these aluminum hangers are thicker than a normal stainless or steel hanger.

 

The magnetic test is inconclusive for aluminum because stainless is also non magnetic.

 

Can't imagine why they would make aluminum hangers, unless it was some kind of short term application. Or some kind of rigging that needed to be light but was inspected/replaced often.

[Patriot]

Exfoliation corrosion is not limited to aluminum only. Austenitic steels will show exfoliation corrosion. While I have my reservations that many, if any, hangers are made from carbon steel. Those made from stainless are prone for the same reasons as aluminum from the manufacturing processes working the grain boundaries.

[Buckaroo]

Exfoliation corrosion is not limited to aluminum only. Austenitic steels will show exfoliation corrosion. While I have my reservations that many, if any, hangers are made from carbon steel. Those made from stainless are prone for the same reasons as aluminum from the manufacturing processes working the grain boundaries.

 

If it was carbon steel the entire corroded area would be dark brown.

 

Stainless might do that after a century submerged in salt water.

[Pete_H]

That hanger is definitely aluminum. It's massively corroded but not with ferrous rust. It has some slight ferrous rust staining, probably from a ferrous bolt nut or washer. Stainless will not corrode like that.

 

Which hanger are you referring to?

[Buckaroo]

Which hanger are you referring to?

the broken one in the photo

 

on Deberdinka's post, the 12th post

[Pete_H]

Yup. That one's definitely fucked.

[stevetimetravlr]

I can state that the bolts on Dana's Arch first pitch are good and not Kong Bonatti. I think they must have been replaced in the mid 90's?

[billcoe]

What Clint, Mark Hanna and Catbirdseat say all appears to be the case. Aluminum hanger/Stainless bolts appears to be an unusual, but bad combo so keep an eye out. Steel/Alum was not uncommon back in the day and seemed as good as anything else (knowing of aluminum's weakness to cycling wear breakage of course) however, stainless/alum was rare.

 

I wanted to cross copy this post from Rockclimbing.com

 

Ciao,

 

I am a climber, hanger producer and, more important for the discussion, an Italian Climber.

Kong is an Italian company, may be I have used about 1000 of those hangers myself and I have seen, who knows, 10K, 20K of them placed.

 

First: there are 3 types of them: Aluminium, Steel and Stainless. The lattest very little used since it's made from 316, so pretty expensive.

All Alu hangers, we all know here, are weak and should be replaced. Period. End of discussion. I think the ropture refers to them.

Some steel one are now showing serious signs of wear. We are as climbing community replacing them.

Stainless looks fine.

 

It's about 8 years that those hangers are very little used. Equippers uses now other brands. Not for an issue with quality, but mainly with price.

 

As a climber and as an equipper, I know when I see there hangers on a route, they might have minimum 10 to 15 years.

Minimum.

I repeat it: minimum 10 years. Period. Easily 15, some 20 years.

 

I need to point out to everybody, that nothing last forever (even stainless) and, all climbers, should not take everything from granted. Climbers should consider that, once in 15 years, everything should be rebolted. Period.

 

Then, if you want, we go on with discussions why it wears out that way. But I think this is not the point.

An inexpensive piece of metal that is out holding falls for 15 years should be replaced.

Let the piece rest in peace!!!!WinkWinkWink

 

Ciao,

E

 

PS if you want to post it in the Cascade forum, be free to do it.

 

from: http://www.rockclimbing.com/cgi-bin/forum/gforum.cgi?post=2246519;page=unread#unread