Zinc plated va stainless steel, anchors chains and quick links

20 kN wrote: I dont think that they will. Some will, but the problem is that some will not. Corrosion is an extremely localized mechanism. I have pulled bolts off routes and tested them to find the first bolt failed at 2kN, the 2nd failed at 35kN, the 3rd at 39kN and the 4th at 4kN. They were all the same bolt, same hanger, installed at the same time by the same person. So while most stainless bolts may last 100 years, random bolts here and there will not. Then the problem becomes that if you cannot trust a random bolt here and there, and you dont know which bolts can be trusted and which cannot because the corrosion is occurring in the hole, then you need to replace them all. The entire area is limited by the lifespan of the weakest bolt, sorta speak, unless you can be confident no corrosion is occurring in the hole, which you could never be if the bolt was 100 years old.

I would be interested in knowing what areas these SS bolts came from and what make and model the bolts were. Rather than spread fear please provide us with relevant information so that we can all decide whether this is a common problem for all climbing areas.

I try to use stainless. its expensive. Its hard to get folks to use anything more expensive than a redhead. on the other side... red heads are strong enough seem to last at least 10-25yrs in zion

Bruce Hildenbrand wrote: I would be interested in knowing what areas these SS bolts came from and what make and model the bolts were. Rather than spread fear please provide us with relevant information so that we can all decide whether this is a common problem for all climbing areas.

This was in a marine environment where the bolts were suffering from SCC, so it's different than your standard desert environment for sure. However, I have seen similar cases in non-marine environments. A common issue related to corrosion that can cause a massive difference in pull-out strengths occurs with wedge bolts. It's quite common that the cone can fuse to the shaft of the bolt, in which case the bolt essentially just becomes a static friction-held anchor with no active caming component. In cases like that, it's not uncommon for one bolt to pull nearly by hand while other bolts on the same route may be extremely difficult to remove and may even require breaking the bolt and drilling the core out. While this is typically an issue more common with plated steel, I can think of at least one case where this has occurred with stainless steel.

I am not spreading fear, I am simply annotating the well-known fact that corrosion resistance can vary greatly depending on a million factors and while a particular stainless bolt might last xxx years in one area, the same bolt might not last 1/2 as long in a nearby area. It's always a possibility, and more so in areas where corrosion is more prominent (e.g. limestone, wet areas, marine, ect.).

Zinc plated quicklinks on SS hangers is okay from my understanding...

@Quicklinks in a "non-marine" environment - 3/8" SS or 1/2" plated?

Marine and tropical environments definitely pose a next-level threat to climbing anchors. Even in cool climates like northern California, it appears that stress corrosion cracking occurs. This is a super-scary type of corrosion, very fast (bolt failure after 3 years) and extremely destructive (new-looking bolts failing at less than body weight). For these areas, titanium glue-ins are the only safe bolt. Rapbolting.com just started distributing for the British company Titan Climbing, who makes titanium bolts.

20 kN wrote: This was in a marine environment where the bolts were suffering from SCC, so it's different than your standard desert environment for sure. However, I have seen similar cases in non-marine environments.

Areas with confirmed SCC are certainly an issue. However, I'm curious if there's any documented SS bolts with corrosion issues in areas without SCC? Jim, 20kn, John? Any that you've come across?

J Achey wrote:Marine and tropical environments definitely pose a next-level threat to climbing anchors. Even in cool climates like northern California, it appears that stress corrosion cracking occurs. This is a super-scary type of corrosion, very fast (bolt failure after 3 years) and extremely destructive (new-looking bolts failing at less than body weight). For these areas, titanium glue-ins are the only safe bolt. Rapbolting.com just started distributing for the British company Titan Climbing, who makes titanium bolts.

SCC occurs in all outdoor environments, it's just a question of how fast. Temperature does play a role in SCC, so tropical environments are certainly going to have more issues. It is however important to note that a "marine environment" is classified as such because of the chloride ions in the water. Many areas may have high chloride concentrations in runoff water that flows over the bolts from chlorides that are picked up from the vegetation and minerals on or above the cliff face. This means that we can have environments as bad or worse than your typical "marine environment" even if they are no where near the ocean.

This post isn't meant to scare everyone since these types of environments are fairly rare, but just as a reminder that harsh environments can and do exist away from the ocean.

kennoyce wrote: SCC occurs in all outdoor environments, it's just a question of how fast. Temperature does play a role in SCC, so tropical environments are certainly going to have more issues. It is however important to note that a "marine environment" is classified as such because of the chloride ions in the water. Many areas may have high chloride concentrations in runoff water that flows over the bolts from chlorides that are picked up from the vegetation and minerals on or above the cliff face.

I can smell the ocean when I drill into most limestone.

I'm not sure SCC in climbing hardware has been noticed anywhere inland, say, in the interior of the Western U.S. And, really, despite some sketchy reporting from certain locations, it really isn't prevalent around the GOBS of fixed anchors near the Mediterranean sea. You'd think, even progressing slowly, we see massive bolt failures at the crags near the sea in Europe. But, there hasn't been.

Maybe its more a "tropical marine environment"? Seems to happen in spots that are way more humid and have more plant decay on the cliff sides?

Be interesting to note if anyone has pulled 20 year old hardware from a relatively dry, non-tropical marine environment, and looked for the start of SCC. Hmmm. Anyone know?

Interesting read:

theuiaa.org/upload_area/Saf…

According to that document, there's been confirmed or highly suspected SCC at a number of Mediterranean locations. Hmmm. More information would be great. Anyone have a source?

Interesting that Minorca is mentioned, but, not Mallorca (which has a GOB of seaside bolted routes).

Crazy scary stuff.

I'm wondering out loud if what could be current "best practices" might change in the next 5-10-20 years as more information becomes available?

Brian in SLC wrote:Interesting read: theuiaa.org/upload_area/Saf… According to that document, there's been confirmed or highly suspected SCC at a number of Mediterranean locations. Hmmm. More information would be great. Anyone have a source? Interesting that Minorca is mentioned, but, not Mallorca (which has a GOB of seaside bolted routes). Crazy scary stuff. I'm wondering out loud if what could be current "best practices" might change in the next 5-10-20 years as more information becomes available?

Ask the UIAA, they are the ones making the claims and basing/justifying their decision making on those claims.
I know of no independently proven occurances of SCC in the Mediterranean in 316 anchors and the occurances in 304 anchors have turned out to be sub-standard materials which were not 304 stainless.
There are many hundreds of thousands of 304 and 316 anchors in place around the Mediteranean coastline.
The belay failure in Sicily mentioned in the report involved neither 304 nor 316 anchors, the route is now rebolted (by the first ascencionist) with 316 hardware which should have been used in the first place.

Brian in SLC wrote: I can smell the ocean when I drill into most limestone. I'm not sure SCC in climbing hardware has been noticed anywhere inland, say, in the interior of the Western U.S. And, really, despite some sketchy reporting from certain locations, it really isn't prevalent around the GOBS of fixed anchors near the Mediterranean sea. You'd think, even progressing slowly, we see massive bolt failures at the crags near the sea in Europe. But, there hasn't been. Maybe its more a "tropical marine environment"? Seems to happen in spots that are way more humid and have more plant decay on the cliff sides? Be interesting to note if anyone has pulled 20 year old hardware from a relatively dry, non-tropical marine environment, and looked for the start of SCC. Hmmm. Anyone know?

Brian, I agree completely with everything you wrote. SCC is not a problem in the vast majority of locations in the time frame that we are talking about. My point was just that SCC susceptible materials will eventually fail due to that mechanism, and that it doesn't have to be in a tropical environment or by the ocean for it to happen. It may take 500 years for it to happen, but eventually it will happen. My guess is that 304 stainless in most of the US will last at least 100 years, and 316 much longer than that.

Interesting to hear different reports about "gradual" SCC. My research led me to understand that SCC was a process believed to have a temperature threshold. Just like paper will never catch fire no matter how long you hold it next to the heat vent in your car, SCC will simply not occur below a certain temperature, regardless of high chloride concentrations. Pitting and crevice corrosion may occur, but those are completely different things, far less catastrophic than SCC. Yet the temperature threshold seems to be lower than originally thought. The bolt failures in Thailand were quite shocking and theoretically interesting to the industrial-accident-analysis community when Angele Sjong (a climber and professional materials-failure analyst) released her paper on that topic, which I assume most of you geek posters (like me) have read.

Sorry, OP. Your post has been hopelessly hijacked.

J Achey wrote: Sorry, OP. Your post has been hopelessly hijacked.

No problem. It wouldn't be a MP post if it didn't go way off the original question/topic..

S. Neoh wrote:@Quicklinks in a "non-marine" environment - 3/8" SS or 1/2" plated?

I would do 3/8" SS unless the links are used to lower off in a sandstone area (e.g. Red Rocks). In that case, the links will be toast well before corrosion sets in.

J Achey wrote:Interesting to hear different reports about "gradual" SCC. My research led me to understand that SCC was a process believed to have a temperature threshold.

If we are talking purely about chloride-based SCC, then that statement is correct, some materials will never* suffer from SCC below a temp threshold. *Never being it will not occur in the serviceable lifespan of the device.

As far as "all" material eventually failing from SCC, that's an entirely moot point for our purposes. Stainless steel in inland environments that is not exposed to chlorides will not suffer from SCC in the serviceable lifespan of the bolt. With the rare, specific exception, there arnt really any cases of SCC occurring in bolts in inland environments. In the rare occasion that I have heard of it happening, it has always occurred as a result of a manufacturing defect (e.g. the 2015 issue involving Fixe anchor chains) or because chlorides were present in the area (one hanger failed from SCC because a chemical plant dumped crap into the rainwater runoff nearby).

Micah Klesick wrote: Areas with confirmed SCC are certainly an issue. However, I'm curious if there's any documented SS bolts with corrosion issues in areas without SCC? Jim, 20kn, John? Any that you've come across?

Absolutely. 304SS is the most common form of SS in use, and it's used in tens of thousands of products. There are plenty of examples where 304 have corroded outdoors and indoors. As far as bolts go, I can think of one example where an anchor was placed on the top of a cliff and the hole was constantly filled with runoff water. After awhile the anchor turned to crap and had to be replaced.

SS in climbing is still fairly new. We really havent been using SS bolts for more than 10 years or so. While there are SS bolts out there older than 10 years, prior to 2005 plated steel was by far the most common choice. As our SS bolts age we will start to see new things I am sure.

Sorry to resurrect dead thread, but it's right on target. Couple comments and a query.

304 isnt marine grade because underwater the passive chromate oxide cant reform. Lots of talk about this on boating forums for anchors (which is how I discovered it - google 'stainless anchor' and you'll find the nexus of climbing and boating (also for knots :).

As for 304 or 316 and SCC in 'marine' or 'chloride' environments, here in Ontario on limestone there's some slabby faces of incredibly dark black rock (stained black by runoff) - this runoff is full of tannins and other soil components from the cliff environ above, which may include chloride.

This creates a nice face angled at the sun, on a 38C day, with black rock, thats moist with runoff. It's quite possible that the bolt hole would be full of chloridated moisture and cooking at 60C.

Like very slow speed limits near schools that apply even in the dead of night, getting people used to the speed in the area ("always go slow in this area at all times"), perhap we should be using titanium bolts because of the 1 in 100 chance that the bolt you place will be in such an environ (there's a heck of a lot of examples of this in Southern Ontario at Devil's Glen and The Swamp climbing areas - black streaked (from runoff) rock, that faces the sun for hours a day).

That said, getting people to 304 is a good start. Here I think everyone's on the 304 train nowadays for the most part, and reequipping continues apace.

Beware: the fixe steel gym anchor biner (with the hex-unlocked locking bar) was advertised by MEC (Canada's answer to REI) as stainless, as were a few other fixed hardware products. I got them to pull and redo their descriptions as they're just plated steel. (ie for gyms, not outside.)

My question: There are often missing hangers (and nuts..) found on routes -- how bad is it to place a stainless quicklink or hanger on a plated bolt/anchor? Wont the plated bolt suffer the corrosion (according to the electrochem series) in this circuit? (Which is actually the OP's question, but I dont think it got answered completely - he went and changed his question in his next post...). Thanks.

Ken Chase wrote: My question: There are often missing hangers (and nuts..) found on routes -- how bad is it to place a stainless quicklink or hanger on a plated bolt/anchor? Wont the plated bolt suffer the corrosion (according to the electrochem series) in this circuit? (Which is actually the OP's question, but I dont think it got answered completely - he went and changed his question in his next post...). Thanks.

Stainless quicklink on a plated bolt hanger, not a problem at all in most environments as there is pretty much never an electrolyte present to promote corrosion.

Stainless hanger on a plated bolt, lots of people want to believe that this is a problem thanks to all the propaganda thrown out there from Fixe Hardware about mixing metals, but the truth is that it's really not much of a problem in most environments either. Probably better to avoid it if possibly, but the change in the life of the bolt is most likely negligible as the plated bolt will suffer from corrosion issues regardless of the hanger used and generally will end up corroding inside the damp or wet hole long before it corrodes at the contact area between the bolt and the hanger (which is where galvanic corrosion would occur).

kennoyce wrote: Stainless quicklink on a plated bolt hanger, not a problem at all in most environments as there is pretty much never an electrolyte present to promote corrosion.

Agreed

kennoyce wrote: Stainless hanger on a plated bolt, lots of people want to believe that this is a problem thanks to all the propaganda thrown out there from Fixe Hardware about mixing metals, but the truth is that it's really not much of a problem in most environments either.

Disagree. Maybe in UT desert its not but, along the east coast of this country, this is horrible advice and simply wrong. We have moist humid climates and mixing metals is a time bomb and should never be done.

Sounds like people should be advised to carry plated hangers instead, to act as the sacrificial anode as they can be inspected visually when the bolt cant - or, perhaps something even slightly more electrochemically active than plated, but I cant think of something that would be safe and act in this way.

Better to replace the bolt, obviously, but the diff between adding a hanger and a nut and redrilling is huge (ie "experienced bolter with a drill and related gear" vs "someone who happens to have a nut, hanger and wrench handy).

So what's the solution without dipping into paranoia?

Does Titanium corrode at all (I am sure in some acidic situation it must -- acid rain musta been a bigger problem for climbers in the 70s/80s!) - so again same issues with Ti with SS304/316 hanging on it?

Ken Chase wrote:Sounds like people should be advised to carry plated hangars instead, to act as the sacrificial anode as they can be inspected visually when the bolt cant - or, perhaps something even slightly more electrochemically active than plated, but I cant think of something that would be safe and act in this way.

As a chemist and climber, I wish everyone in this endless "mixed metals" discussion would become familiar with the sacrificial anode concept. It could be developed and used to a significant benefit. And it's not at all new; it's what "plated steel" refers to, after all. The outboard boat motor and underground fuel storage tank industries figured this out a long time ago.