SRB sponsored bolt corrosion - this time at Kalymnos

I've just posted my report on the bolt failure at Ourania cave on Kalymnos. These failures can be tricky because they show zero signs of underlying weakness to the outside world.

Super interesting and fairly terrifying.  Thanks for posting.

Figure I'd repost the negative results of my earlier Iodine-Azide test of a stainless 304 hanger that was showing slight corrosion pulled from a marine environment:
https://www.youtube.com/shorts/NGI_Xwsh3Fo
We tested: the stainless washer, pyrite (positive control), and a rusted bolt from a non-coastal crag (negative control).

Have you ever seen a negative Iodine-Azide test on a failed stainless bolt?

bmdhackswrote:

Super interesting and fairly terrifying.  Thanks for posting.

Figure I'd repost the negative results of my earlier Iodine-Azide test of a stainless 304 hanger that was showing slight corrosion pulled from a marine environment:
https://www.youtube.com/shorts/NGI_Xwsh3Fo
We tested: the stainless washer, pyrite (positive control), and a rusted bolt from a non-coastal crag (negative control).

Have you ever seen a negative Iodine-Azide test on a failed stainless bolt?

I'm stoked to see people using the Iodine-Azide test. It really is a definitive means of distinguishing SSC corrosion from other modes of stress cracking.

Have I ever seen a cracked bolt that tests negative to this reagent? Yes I have a couple of examples, but they are rare. However, they are also very interesting given that I'm always looking for the dreaded SCC. It really doesn't seem to exist outside of the laboratory and industrial processes.

One example I have came from northern Queensland was where the bolt was found blackened at the base of the crag. This, I'm reasonably sure, is a case of lightening strike. Others that I have, can be traced to a batch of home-made U-bolts where the 316 bar stock was sensitized during manufacture, and all have developed IGC cracking at the outer bend surface after some years in service. I also have an example of bolts on a sea cliff in southern Brazil where all have failed in the manner of SRB attack, but no sulphide is present. Also the microstructure is quite anomalous. I suspect this is a case of excess sulphur within the steel itself, but need to do a lot more thinking and experimenting to draw a solid conclusion. There is no doubt that a high sulphur steel like 303 is a bad idea, and climbers have sustained severe injuries when such bolts have failed. It doesn't need to be a sea cliff for this to occur. I don't have enough data on 303 failures to draw solid conclusions, but I am working on simple tests by which route equippers could determine if they have been sold 303 in place of 304 or 316.

Wow, scary stuff! Thanks for sharing this info. 

Seems like there is a good path forward for identifying and mitigating the danger. Science!

Dave, you are doing exceptional, leading-edge work and I think everyone thanks you for it.  Excellent report!!    

I do have some comments on your report:

This is the “black ring of death”, so named by John Byrne many years ago when he was describing the catastrophic bolt failure that was occurring on Cayman Brac.

I can't take credit for that!  If I remember correctly, it was Sam Lightner or one of the other Thai guys (Cecil?  Josh?) who first called it that.  

We have evidence from the UIAA sponsored test sites in Railay/Tonsai, now coming into their 10th year. Simply based on observation, I assess 304 anchors to be in dire trouble, 316 to be pretty good, but definitely showing some superficial signs of corrosion, while titanium and the super-austenitics look as good as new. Make of that what you will. It is still early days, and the final destructive analysis must wait another ten years.

The oldest Ti bolts on Cayman Brac are now 25 years old. They not only "look good as new" as you mention above, they look brand-new, no simile needed.  And we've not had a failure of any kind.  

Note that I use the phase “seems to work”. This is not because I doubt the evidence, but because I am painfully aware that I don’t understand the mechanism for such resistance. It is actually worse than that, my chemistry 101 tells me that titanium should be quite unsuited to the reducing conditions that prevail just below the surface of the bolt hole. 

Sounds like the this is the next logical step for your research.  Meet me down there next year and you can do as many tests as your heart desires... and maybe a climb or two.  

John Byrneswrote:

Dave, you are doing exceptional, leading-edge work and I think everyone thanks you for it.  Excellent report!!    

I do have some comments on your report:

This is the “black ring of death”, so named by John Byrne many years ago when he was describing the catastrophic bolt failure that was occurring on Cayman Brac.

I can't take credit for that!  If I remember correctly, it was Sam Lightner or one of the other Thai guys (Cecil?  Josh?) who first called it that.  

We have evidence from the UIAA sponsored test sites in Railay/Tonsai, now coming into their 10th year. Simply based on observation, I assess 304 anchors to be in dire trouble, 316 to be pretty good, but definitely showing some superficial signs of corrosion, while titanium and the super-austenitics look as good as new. Make of that what you will. It is still early days, and the final destructive analysis must wait another ten years.

The oldest Ti bolts on Cayman Brac are now 25 years old. They not only "look good as new" as you mention above, they look brand-new, no simile needed.  And we've not had a failure of any kind.  

Note that I use the phase “seems to work”. This is not because I doubt the evidence, but because I am painfully aware that I don’t understand the mechanism for such resistance. It is actually worse than that, my chemistry 101 tells me that titanium should be quite unsuited to the reducing conditions that prevail just below the surface of the bolt hole. 

Sounds like the this is the next logical step for your research.  Meet me down there next year and you can do as many tests as your heart desires... and maybe a climb or two.  

Thanks for the kind words, John.

Perhaps you weren't the first with "black ring of death", but yours was certainly a prominent voice in pushing to get Safe Com to understand there was a very real issue that wasn't going to go away.

I'd love to catch up with you at the crag, and who knows I might get there, but four years in I am still recovering from a severe brain injury (climbing accident). I really can't complain because that part of it that does the chemistry was left unscathed, it is more vision and physical coordination that took the knock. I'm simply happy to still be able to do something useful for the community.

This is what mountain project should be

David Reevewrote:

I'd love to catch up with you at the crag, and who knows I might get there, but four years in I am still recovering from a severe brain injury (climbing accident). I really can't complain because that part of it that does the chemistry was left unscathed, it is more vision and physical coordination that took the knock. I'm simply happy to still be able to do something useful for the community.

All that makes your work even more impressive.  Thank you again.  

David Reevewrote:

I've just posted my report on the bolt failure at Ourania cave on Kalymnos. These failures can be tricky because they show zero signs of underlying weakness to the outside world.

Scary and really great info David.  Thanks!

Thank you very much for your excellent work on this, both here immediately, and history.

You're a champ David! Thanks for all your work and I wish you a full recovery sooner than later.