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Protect ya neck (aka Bad bolts in Sardinia)


Original Post
Dustin B · · Steamboat · Joined Jan 2006 · Points: 1,300

Not new news to those who are in the know, but thought I'd post a link anyhow. Many people are completely unaware of the corrosion issue at seaside limestone cliffs.

In april my wife and I went to Sardinia. The place is absolutely a paradise, and I am going back as soon as I can afford to.

However, it ain't perfect. We went to many beachside crags and found much of the fixed hardware uninspiring. Bad enough that we avoided climbs and entire crags in favor of ones with better hardware (usually inland a bit). The locals in the area have been catching onto the real deal when it comes to sea cliffs and fixed hardware. A while back they went through and replaced alot of the old stuff with stainless 5 piece and wedges. Seems the stainless stuff doesn't do too well either...

Shortly after we left, an accident occoured on one of the routes that we walked to the base and decided not to climb due to the condition of the hardware. In this case a visiting swiss dude took it upon himself to do some upgrading. Awesome! Problem is he spent 4000 euro and only redid 25 routes.

Anyhow, go to Sardinia,like right now. It's awesome and the local people are top notch. Just be aware of the issues concerning fixed gear near the sea, I'm glad I was.

http://www.planetmountain.com/english/News/shownews1.lasso?l=2&keyid=42820

John Byrnes · · Fort Collins, CO · Joined Dec 2007 · Points: 582

Dustin, Kudos for posting here. You are right to warn people.

However, as well-intentioned as Louis is, rebolting with "Marine Grade" stainless steel (316/316L) is futile. He's wasting his money. ALL Series 300 stainless steel will crack in that environment, even glue-ins. The UIAA knows this but is dragging their feet on making it public due to politics.

A big problem is that many climbers think that seawater is the primary cause of Stress Corrosion Cracking (SCC), and therefore what works for boats should work for bolts. But boats live in water and bolts live in rock, and it's water-borne ions from the rock as it dries that causes SCC.

Moving inland sometimes improves your safety but inland bolts crack too; it just takes a little longer.

The following image is a broken bolt from Sardinia.

Classic broken stainless bolt. Absolutely NO visible indication of cracking.
This image is from Kalymnos, which has the same environment as Sardina. In fact ALL Mediterranean Limestone has the same problem.
A approximately 10 year old Raumer 316 "marine grade" stainless steel bolt in Kalymnos.

These glue-in bolts, ~10 years old, broke with a tap of a hammer. Notice the sharp edges and granular surface at the break. There's no ductile (pulled taffy) material which indicates they were completely cracked through before being struck.

There is hope that certain stainless steel alloys, such as 904 and 2205, will not crack when used as bolts, but that remains to be proven. Currently, the only proven material is titanium, with 15 years of perfect service in the harshest environments.

David Coley · · UK · Joined Oct 2013 · Points: 70

John, does this imply that we would be better off cutting slots for nuts on easier routes on sea cliff limestone? I've never worked out why this isn't done.

I don't expect it would work on steep hard stuff where one needs to clip fast, but on the 4,5 and easy 6's it would seem possible.

Finn The Human · · The Land of Ooo · Joined Jul 2008 · Points: 106

I'm not a bolter, but I thought I'd read that titanium glue ins were the solution to seaside corrosion. Is that not the case?

John Byrnes · · Fort Collins, CO · Joined Dec 2007 · Points: 582
David Coley wrote:John, does this imply that we would be better off cutting slots for nuts on easier routes on sea cliff limestone? I've never worked out why this isn't done. I don't expect it would work on steep hard stuff where one needs to clip fast, but on the 4,5 and easy 6's it would seem possible.
Yes, removable gear would be a good solution. As far as cutting slots... that I leave to you!
John Byrnes · · Fort Collins, CO · Joined Dec 2007 · Points: 582
Finn the Human wrote:I'm not a bolter, but I thought I'd read that titanium glue ins were the solution to seaside corrosion. Is that not the case?
You may have missed my last sentence buried under the photos, but you're right, titanium is currently the only proven solution.

Also, be aware that inland bolts corrode from SCC too! Being exposed to salt spray is a catalyst, so seaside stainless bolts break sooner, but salt spray is not necessary for SCC to proceed.

BACKGROUND (Reposted)

When Sport Climbing started back in the ’80s, all manners of bolts were used, many of which were too weak to hold multiple falls and most of which would rust or have galvanic corrosion in a few years. This was a clear and present danger to all climbers.

Afterwards came a period of time I’m calling the Stainless Era. Stainless steel quickly became the defacto standard because it was clearly far better than what we had. Stainless steel bolts, both expansion type and glue-ins, quickly populated cliffs throughout the world and the popularity of Sport Climbing skyrocketed.

Stainless bolts, made almost exclusively of “Series 300” stainless steel, solved the problems of strength, rust and galvanic corrosion. At the time, no one suspected we had only removed another layer of the onion. Few climbers had ever heard of Stress Corrosion Cracking (SCC) and no one believed it could happen to a climbing bolt.

In the early 2000’s P. Muraleedharan, a professional metallurgist, wrote that the occurrence of Stress Corrosion Cracking (SCC) in austenitic stainless steels (Series 300) in ambient conditions “depends on the patience of the observer.” In other words, all you need to do is wait and SCC will occur. This was a huge divergence from previous metallurgical doctrine which stated that SCC could never happen in temperatures under 80C (176F).

Few metallurgists believed him until 2008 when Angele Sjong published her analysis of a 316 bolt hanger in a peer-reviewed article in the ASTM Journal of Failure Analysis. Of course by this time climbers in Thailand and Cayman Brac had been dealing with breaking stainless bolts for a decade and broken stainless steel bolts and hangers were being reported all over the world.

No matter if the cliff is marine or inland, tropical or temperate, rainy or moderate rain, of sandstone, limestone or basalt, stainless bolts and hangers are breaking. They have broken in Thailand in as little as 9 months. In Kalymnos, about 9 years. Muraleedharan was right.

The UIAA’s upcoming corrosion guidelines will NOT approve Series 300 stainless bolts for most outdoor environments. The goal of the guidelines is that bolts should be safe for at least 50 years and in many places should far exceed that.

The rate at which SCC proceeds in stainless climbing bolts is determined by four accelerants:

1) Higher temperatures accelerate corrosion.

2) Rainwater dissolves rock creating ions and the ions are carried to the bolts in the runoff either over the surface or by percolating through the rock (limestone & sandstone). The runoff wicks into the crevices behind bolt hangers and into bolt holes due to the capillary effect.

As the water evaporates, the ions re-combine into new compounds, which are concentrated by the “crevice effect”. After each cycle of rain/dry, these corrosive agents becomes more concentrated. The bad ones are Magnesium Chloride, MgCl2, and Calcium Chloride, CaCl2, which are highly corrosive and trigger SCC.

3) Carbonic Acid from rotting vegetation accelerates the dissolution of rock by rainwater, thus increasing the number of ions in the runoff. It also acts as a catalyst for corrosion when deposited on the bolts by rain runoff.

4) Seawater has a high concentration of dissolved Cl, the other half of MgCl2 and CaCl2. Thus sea cliffs develop SCC most rapidly but it’s wrong to think that seawater is necessary for SCC and that inland areas are safe. SCC has been found far inland in Cuba, Taiwan and Okinawa. In Cuba, for example, the cliffs are 26 miles (43km) from the sea.

The above factors explain things like why tropical areas are worse than temperate areas; why sea cliffs are worse than inland cliffs; why glue-ins (no crevices) last longer than expansion bolts; why the bolts at the bottom of the cliff are worse (the runoff has longer to collect ions and unfortunately low bolts also see the highest fall factors), why limestone is worse than granite, and why no one’s yet seen SCC in alpine (too cold) or desert (too dry) environments.

If you look at climbing forums world-wide over the last 5 years, replacing corroding stainless steel bolts is a very hot topic. And if we don’t change our ways, it will continue to be a very hot topic. We need to get out of the rebolt mind-set, and get into the bolt-it-once mind-set.

The bottom line is that anyone who replaces a corroded stainless steel bolt with another stainless steel bolt is wasting their time and money, and creating a future hazard for other climbers. The new bolt will soon corrode as well, and a few years down the road someone else will spend more money and more time and drill more holes to replace it.

Currently, titanium bolts are the only certified bolts proven to be SCC resistant.
Brian in SLC · · Sandy, Utah · Joined Oct 2003 · Points: 14,995

Bolts I've heard about that were sketchy in Sardinia weren't stainless.

The bolts that broke and were replaced in Kalymnos weren't stainless, AFAIK. I trust Aris on this much more than someone who didn't take the photo's.

I think if stainless bolts were an issue in the Mediterranean areas, it'd be a huge and widespread issue. There are 10's of 1000's of bolts on crags from Spain, France, Italy, Greece, Croatia, Turkey...and, they just aren't failing. The ones that look terrible and break aren't 300 series stainless, but, plated bolts.

Could it be an issue? Sure. But, there's no strong evidence of it. Despite pictures of broken bolts that folks claim to be from somewhere, and, claim to be stainless.

ALL Series 300 stainless steel will crack in that environment, even glue-ins.

Well...they aren't all cracking.

Not here:

Capo Noli Finale Ligure, Italy

Nor here (but the plated bolts look terrible!):

Isula Rossa, Corsica

Domestic:

Otter Cliff, Acadia, Maine

Closer to Greece:

Akyarlar, Turkey

Reason for referencing the above, is, these aren't inland crags. These are pretty much on the water. These and many other seaside areas on the Mediterranean just aren't seeing widespread failures.

I want to believe...I just don't see the evidence. And, certainly haven't seen it firsthand in the number of locations I've climbed at over there.

If it really is an issue, then, its a HUGE issue.

Nick Votto · · Unknown Hometown · Joined Jul 2008 · Points: 320

TONS of bad bolts in Sardegna....just gotta be aware. Problem seems to be there's only a small local community of climbers and they cant' re-equip the thousands of routes there. Lots of tourists climbing obviously but they just go through and probably don't even think of the issue that much .....it would be cool to see an ASCA type organization in Italia take charge of this. I would think Maurizio Oviglia has probably made an effort towards it already.

John Byrnes · · Fort Collins, CO · Joined Dec 2007 · Points: 582
Brian in SLC wrote:Bolts I've heard about that were sketchy in Sardinia weren't stainless. The bolts that broke and were replaced in Kalymnos weren't stainless, AFAIK. I trust Aris on this much more than someone who didn't take the photo's. I think if stainless bolts were an issue in the Mediterranean areas, it'd be a huge and widespread issue.
The first stage of SCC is DENIAL.

It IS a huge and widespread issue. Go look at climbing forums world-wide. I think you'll find that just about every one of them has a forum dedicated to bolt replacement and that many of the bad bolts are stainless.

I'd say every Mediterranean climbing area has a spectrum of Series 300 stainless bolts including "plated" bolts. So the time-to-failure will vary according to the alloy and whether it is plated, a glue-in or expansion bolt. So just because one bolt fails sooner then one next to it, it doesn't mean the broken one wasn't stainless or was plated. It also doesn't mean the unbroken bolt will stay that way.

If you don't believe me, will you believe Alan Jarvis, Materials Engineer and leader of the UIAA safety committee responsible for developing anti-corrosion standards for climbing bolts?

I quote from an email he sent me, et al, in May of 2013, when we were discussing the role of Mg+. My previous post on this topic (above) is a distillation and refinement of this information written for the layman. Notice that he doesn't qualify his opening statement by addressing plated or Marine Grade (316) bolts, and that's intentional.

"It is VERY well known that chloride SCC can happen to austenitic stainless steels. That is, the 300 series. But conventional wisdom was it only happened at temperatures higher than about 50 Celsius. Well, except for some isolated cases.

However, research work by Shoji and then Prosek, as well as a few more, showed it COULD happen with a salt crust at lower temperatures. Oldfield & Todd did a failure analysis on the swimming pool roof collapses and used Shoji's work to explain: it was due to a salt crust.

Then Angele did a failure analysis on the Thailand failures and found was also due to a salt crust. Made worse by acidic conditions and high Mg levels from the karst. She based it on the research reported by Oldfield, and a few tests she did herself. She didn't have access to Prosek yet, but he just added to what she already knew from what Oldfield had said. Same conclusions.

So what does Mg do? It PRIMARILY affects the concentration of chloride. So far that's ALL we know.

If you put a drop of NaCl on 316 and leave it under controlled humidity it will not crack.....even for a VERY long time. If you put a drop of CaCl on it, it DOES crack., in a few weeks. A drop of MgCl2 it also cracks, also in weeks. Or CsCl2 it cracks too, in weeks.

WHY?

It is the CHLORIDE in each case that is doing the nasty work: NOT the Mg, or the Na, or the Ca or the Cs.

What happens is that a SATURATED salt made of NaCl is just not concentrated enough to have a critical level of chloride to crack: at low temperature. If you had it at over 50 Celsius then you expect to see cracking if you left it long enough. At 80 Celsius would expect quicker cracking.

Now the chemistry is that a SATURATED solution of MgCl2, or CaCl2 or CsCl is indeed concentrated to cause problems in quite a short time. In lab tests. Or a MIXTURE of salts. But NaCl on its own is NOT.

And we see to see this in real life. We get FAST SCC in Thailand, but we also get it on non-limstone rocks. Unfortunately not very well documented....hence Matteo and hopefully others will help.

(Incidentally the University of Cape Town is about to release a failure analysis of some failed samples, but i'm not sure if all SC, some are due to 303 (high sulphur levels).

So you can see there is no particular DIRECT magic with Mg. It just makes the chloride concentration higher in a saturated solution.

Thus you would expect the SAME sorts of issues with cracking on a basalt or sandstone cliff with sea salt crusts on the anchors. Maybe take a bit longer. But still expect SCC to occur within a few years.

HOWEVER, what is known to affect the story is acid level. If you have a more acidic environment it can make SCC happen QUICKER. But it will STILL happen without it if:
- you are in the critical humidity range
- you have enough stress
- you leave it long enough without washing off the crust

And for sure, the presence of Mg can affect the acid level. But that's an INDIRECT effect."


- Alan Jarvis, 5/16/13

theuiaa.org/news-865–Safety-Commission-issues-update-of-corrosion-notice-for-anchors-in-marine-locations-.html
Dustin B · · Steamboat · Joined Jan 2006 · Points: 1,300
Brian in SLC wrote:Bolts I've heard about that were sketchy in Sardinia weren't stainless. The bolts that broke and were replaced in Kalymnos weren't stainless, AFAIK.
We saw both stainless and non-stainless bolts that had corrosion. One area, Cala Luna, had been rebolted sometime around 97-99 according to the guidebook, with stainless. Many of these looked "ok" but quite a few looked horrible. The hangars were stamped stainless (inox) though one can't be too sure of the bolts. Mr Oviglia and the other locals do a lot of bolting and do a great job so I would assume that they are stainless also. Same goes in the cave of Biddiriscottai, which were redone in '01 by the local Alpine Rescue Team, full stainless and some looked sketchy. These two spots in particular are exposed to an almost ever present sea spray fog that just hangs on the beach.

"Reason for referencing the above, is, these aren't inland crags. These are pretty much on the water. These and many other seaside areas on the Mediterranean just aren't seeing widespread failures.
I want to believe...I just don't see the evidence. And, certainly haven't seen it firsthand in the number of locations I've climbed at over there.
If it really is an issue, then, its a HUGE issue."

I didn't mean to Make it seem like all sport climbs there are death routes, or that rusty bolts are just falling out of the rock when sneezed on. Perhaps I should change the title of my thread, it is a little dramatic. I'm sure that if you went around the island and whipped on every single bolt, once, the percentage of failures would be relatively low. I just wanted to start a discussion in hopes that people who don't know about this can make more informed decisions about what to climb and hopefully to optimize their systems. We still climbed a ton of rock both on the beaches and inland, but were more selective than most of the other tourists who were happily whipping on poor looking gear without hesitation (I know, It's europe).

John:"Moving inland sometimes improves your safety but inland bolts crack too; it just takes a little longer."

then,

"Also, be aware that inland bolts corrode from SCC too! Being exposed to salt spray is a catalyst, so seaside stainless bolts break sooner, but salt spray is not necessary for SCC to proceed."

I didn't mean to give the impression that this was a problem limited to seaside cliffs or that we found a false sense of security on cliffs that weren't overlooking the sea. There are of course some manky looking bolts on the inland crags too and we approached these with the same mentality that I approach all bolts with. But we found these crags had (generally) better looking hardware than the beach crags. I think due to two reasons:

1-The crags on the beaches had hardware that, according to the book, was generally older than the crags that weren't right on the beach. I think this is due to the beach crags being developed earlier being more accessible and desirable.
2-the sea spray creates a fog that just hangs on the beaches really hammers on the bolts and of course overhanging routes that seep alot.

But what to do? On a personal scale, there is always the obvious:never trust a single point and always try to back up, don't clip into only one point (or even go off belay) when threading an anchor, etc etc...the usual stuff.Be picky when choosing routes. If the hardware looks like shit, smells like shit (hmmm), then it's more likey to be shit.
On a bigger level, organized rebolting is a short term solution, but if the gear goes bad every 5-20 years, then it can be a waste of both time and money. Also in the tourist areas it's probably challenging with lots of non locals putting up routes with whatever hardware they have, and likely not intending to return every so often to rebolt all their routes, leaving the locals with tons of routes and potentially substandard gear. Of course it's easy to say that people should be more conservative with their route development. All being said, I would gladly give money to local organizations at the places I visit for hardware maintenance. In some areas like Arco, the local government has taken to maintaining many local crags as if they were city parks. In other areas the local guides and shops have adopted crags (RockStore in Finale Ligure for example) and taken on the task of rebolting routes. I have no idea what is the best way forward in Italia, but look at Rifle, maybe the way they have handled the hardware situation there would be a start.
Brian in SLC · · Sandy, Utah · Joined Oct 2003 · Points: 14,995
Dustin B wrote: In other areas the local guides and shops have adopted crags (RockStore in Finale Ligure for example) and taken on the task of rebolting routes. I have no idea what is the best way forward in Italia, but look at Rifle, maybe the way they have handled the hardware situation there would be a start.
Ugh. Gnarly issue.

Yeah, I dunno. Inconel 718 for my hangers and bolts, please (ha ha).

Be nice if hangers were available in Ti and bolts as well. I have a couple I picked up somewhere, similar to the Petzl Longlife bolts, that were Ti and came with a hanger. Light and well made. Russian I think. Another example was a simple expansion bolt/hanger combo. Have to see if I can dig them up for reference.

Be interesting to follow what the UIAA comes up with. I'm just glad I don't install fixed anchor in/near a marine environment...

Clip, tug hard, and hope for the best...!

Scary stuff.
John Byrnes · · Fort Collins, CO · Joined Dec 2007 · Points: 582

Dustin, you've got it right about inland/sea-side, etc.

You're also right on the money in that "what to do?" isn't always a simple answer.

Just like your original post, I try to spread awareness of the problem. As people become aware, they will (eventually) change their actions, and hopefully switch to other materials besides Series 300. The UIAA guidelines are now almost a year "overdue" (in my mind), I keep pinging Alan but... ;-(

The second thing I do is to bolt/rebolt exclusively with Ti bolts in Cayman Brac. In places where SCC is proven, this is the only responsible material to use.

Brian, you posted a picture of Arcadia. So far, we have not heard of ANY bolts failing due to SCC that were placed in granite! We expect to find them in sea-side granite because seawater has rather high levels of dissolved Mg and Ca, but we have not, and we (myself, Alan, et al) don't know why. Limestone seems worst, then basalt, then sandstone.

The Chinese company "Keith" produces Ti expansion bolts w/ hangers, but they look sketchy and cost $40ea. Ti is difficult to machine. Titan Climbing,titanclimbing.com, is currently the only place to buy certified Ti bolts and products that I know of.

zHoltzman · · Boulder, CO · Joined Nov 2007 · Points: 5
Brian in SLC · · Sandy, Utah · Joined Oct 2003 · Points: 14,995
John Byrnes wrote:So far, we have not heard of ANY bolts failing due to SCC that were placed in granite! We expect to find them in sea-side granite because seawater has rather high levels of dissolved Mg and Ca, but we have not, and we (myself, Alan, et al) don't know why.
Crazy. Corsica is mostly granite as well.

Anchor on Isula Rossa, Corsica

Old bolt - Isula Rossa, Corsica

Things that make you go, hmmm....
mpulquerio · · Unknown Hometown · Joined Nov 2014 · Points: 0

I live in Portugal and we have many spor climbing crags that are seaclifs. Recently, many bolts have broken at bodyweight or with a simple pull! Fortunately, until now without any injuries to the people involved.

All the bolts that have broken were stainless steel 304. Some of them were only 7-8 years old. This has happen in different types of rock: limestone, granite and basalt. All of them were placed in crags that are very exposed to spray from the sea, which means that they are exposed to high levels of salt. Also, in the summer the temperature of the rock can be quite high. However no study has been conducted to find out if these are in fact the conditions that make these bolts prones to break.

Additionally to maillon rapids of stainless steel 316 have been broken at bodyweight. No bolts from 316 have however been broken.

To add to all this we have found to be very difficult to distinguish the bolts that are in bad conditions. Some of the bolts that have been broken look ok at visual inspection. As you could imagine this leads to a very dangerous situation, since the climber cannot say anything about the safety of the bolt be visual inspection. This leads to a type of russian roulette when you fall on the bolts!

We have now a big project to rebolt these crags with titanium bolts. These are however quite expensive and the rebolting is going slower than we would like. In case you are interested have a look athttp://climbingpt.com/titan-project/the-problem/

I am afraid that like in Portugal and Sardinia this is very common in the mediterranean area. accidents have recently happen on Sicily because of this.

Be careful and be safe

John Byrnes · · Fort Collins, CO · Joined Dec 2007 · Points: 582
Brian in SLC wrote: Crazy. Corsica is mostly granite as well. Things that make you go, hmmm....
BTW, the bolt in your bottom photo is clearly NOT stainless. That's common rust in a uniform layer, thus it's mild steel. Possibly it was galvanized and the Zn is now gone.

Many people look at a "rusty looking" bolt, and assume it's not stainless. But bolts pitted and cracked by SCC looks rusty, but not it the same way. Stainless will "rust" only where it is pitted or cracked, and thus the rusty parts are patchy and non-uniform (in general).

The photo of a hanger at the link posted above (climbingpt.com/titan-projec…) is a CLASSIC example of rusty-looking stainless steel that's being pitted/cracked by SCC. Here's another; notice the rust is not uniform on identical surfaces.

An unsafe corroding stainless steel bolt and the titanium bolt that replaced it. Cayman Brac circa 2001. Photo by Skip Harper.
John Byrnes · · Fort Collins, CO · Joined Dec 2007 · Points: 582
mpulquerio wrote:I live in Portugal and we have many spor climbing crags that are seaclifs. Recently, many bolts have broken at bodyweight or with a simple pull! Fortunately, until now without any injuries to the people involved. All the bolts that have broken were stainless steel 304. Some of them were only 7-8 years old. This has happen in different types of rock: limestone, granite and basalt. All of them were placed in crags that are very exposed to spray from the sea, which means that they are exposed to high levels of salt. Also, in the summer the temperature of the rock can be quite high. However no study has been conducted to find out if these are in fact the conditions that make these bolts prones to break. Additionally to maillon rapids of stainless steel 316 have been broken at bodyweight. No bolts from 316 have however been broken. To add to all this we have found to be very difficult to distinguish the bolts that are in bad conditions. Some of the bolts that have been broken look ok at visual inspection. As you could imagine this leads to a very dangerous situation, since the climber cannot say anything about the safety of the bolt be visual inspection. This leads to a type of russian roulette when you fall on the bolts! We have now a big project to rebolt these crags with titanium bolts. These are however quite expensive and the rebolting is going slower than we would like. In case you are interested have a look athttp://climbingpt.com/titan-project/the-problem/ I am afraid that like in Portugal and Sardinia this is very common in the mediterranean area. accidents have recently happen on Sicily because of this. Be careful and be safe
mpulquerio, thanks for posting.

What you are describing is "classic" SCC affecting a large and popular climbing area. You are doing the right thing by rebolting with Ti, it will be cheaper in the long run!

I'm glad you mentioned the broken Maillon Rapid, because many people thought these wouldn't be affected because they weren't in direct contact with the rock. But they break too!

This cracked stainless lowering ring is from Thailand. In order to keep the titanium anchor bolts from being worn-out from lowering, they tied sections of rope to the bolts and to a stainless lowering ring which is easily replaced. Everyone was surprised when they found these rings crack!

Thai lowering ring
mpulquerio · · Unknown Hometown · Joined Nov 2014 · Points: 0
John Byrnes wrote: I'm glad you mentioned the broken Maillon Rapid, because many people thought these wouldn't be affected because they weren't in direct contact with the rock. But they break too!
Yes we were very surprised also, as they are not in direct contact with the rock. Even more strangely is that the stainless steel 316 bolt where the two maillons were placed did not brake!

Despite some studies have been done in world about this, the fact is we do not understand exactly what is going on. I sincerely hope we do not received bad news regarding the use of titanium bolts as they have not been used for long enough, and in the past we have also think that stainless steels bolts were the solution...
John Byrnes · · Fort Collins, CO · Joined Dec 2007 · Points: 582
mpulquerio wrote: Yes we were very surprised also, as they are not in direct contact with the rock. Even more strangely is that the stainless steel 316 bolt where the two maillons were placed did not brake! Despite some studies have been done in world about this, the fact is we do not understand exactly what is going on.
Looking at the photos and reading the description of the environment, I'm quite certain it's SCC.

If you want to be certain, take samples of bad hardware to a local university that has a metallurgy/materials engineering lab. Many universities will do an analysis for free. A commercial lab may charge as much as $20,000.

mpulquerio wrote:I sincerely hope we do not received bad news regarding the use of titanium bolts as they have not been used for long enough, and in the past we have also think that stainless steels bolts were the solution...
We have Ti bolts in Cayman Brac and Thailand that have been in service for 15 years. They show absolutely NO signs of corrosion at all in an environment where stainless steel breaks in 9 months (Thailand) to 18 months (Cayman).
Brian Sabo · · Unknown Hometown · Joined Feb 2012 · Points: 10

SCC requires both corrosion and a sustained tensile stress. While the expansion bolts are in tension, a glue in bolt would not be. Wouldn't this suggest a different failure mechanism for the glue-ins?

Brian in SLC · · Sandy, Utah · Joined Oct 2003 · Points: 14,995
Brian Sabourin wrote:SCC requires both corrosion and a sustained tensile stress. While the expansion bolts are in tension, a glue in bolt would not be. Wouldn't this suggest a different failure mechanism for the glue-ins?
Might be residual stress in a glue in from the bending/forming process. Would still have a stress field, methinks.
Guideline #1: Don't be a jerk.

Fixed Hardware: Bolts & Anchors
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