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Fixed Hardware Etiquette? and a question re: glue-in bolts
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This isn't cutting edge research - it's a fundamental concept studied in civil mechanical engineering, chemistry, material science, and a host of other fields. https://en.wikipedia.org/wiki/Galvanic_corrosion If the electrolyte is not present, then no corrosion can occur. The metal-metal interface will get wet occasionally but will dry quickly because it is incredibly small and exposed to the air. Unless it stays wet for long periods of time the galvanic corrosion that occurs will be negligible. So, unless you are replacing quick links in a rain forest . . . Let's assume that you are correct, and that significant galvanic corrosion will occur between the plated quicklink and the stainless steel bolt on a route. Plated steel is more anodic than stainless, so the quicklink degrades instead of the hard to replace glue-in. Since stainless steel quicklinks are about 3x the cost of a plated quicklink and the quicklink is easy to monitor and replace if necessary, I take back my statement about both choices being equal - plated is without a doubt the better choice. |
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This article seems to have a good explanation. http://www.worldstainless.org/Files/issf/non-image-files/PDF/Euro_Inox/Contact_with_Other_EN.pdf |
James Schroeder wrote: I'm sorry, really really really trying not to be a jerk here, but it's getting harder and harder with each post you make. No, I didn't ever say that galvanic corrosion can be a problem in humid environments, it's not (for the external portions of the anchor). I said to use stainless because of general corrosion which has nothing to do with galvanic corrosion. No, climbtech doesn't sell their wave bolt tool to prevent galvanic corrosion, the sell it because if you pound on a stainless bolt with a non stainless hammer it can damage the protective chromium layer and can deposit iron from the non stainless tool onto the damaged portion of the stainless bolt which makes for a perfect spot for general corrosion to begin making the stainless no longer stainless. No, galvanic corrosion is not a low-probability issue in dry environments, it is a zero probability issue, and even if it were an issue, the consequences of failure are not worthy of consideration because on the external portions of an anchor it is extremely easy to see if corrosion is occurring. No, matching metals are not a better combination in all environments, in fact, it is so unimportant that even Hilti, one of the largest anchor bolt manufacturers in the world (who I guarantee you understands galvanic corrosion) uses stainless steel clips on their plated steel wedge bolt the Hilti KB-TZ. As was mentioned by someone else, galvanic corrosion is a very well understood phenomenon, and it is well understood that it won't happen on the portions of an anchor that are out in the air because once again, there is no electrolyte present. |
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I can vouch for Ken's expertise in this area (of course who am I? Just some other guy on the internet). This corrosion topic starts a rubber sword fight every time. The science is well understood. Application is different. For instance, you're confusing the bolt hanger/stud metal combination (lots of surface contact area and where water can be trapped) to a quick link on a hanger where there is very little surface contact, let alone an area where water can be trapped. There are more dissimilar metal combinations on your car and bicycle! Aluminum and steel have even more galvanic potential when compared to plated vs. stainless steel. But that's not stopping you from putting quick draws (or leaving them on your proj) for long periods of time. Matching metals is a good idea in general. But for this case, it doesn't really matter. |
Ken Noyce wrote: I think you're mistaking my questioning and my line of reasoning, and maybe we're getting off track. My original claim was: Your direct response was: I think where we're getting hung up is what I've highlighted in bold. I'd guess we have different definitions of wet/humid environments and/or we're both probably overestimating the the amount of climbing that takes place in environments similar to those we each live in. Layton, UT get 17.34 inches of precip annually, whereas Sauk County, WI gets 35.57 inches - more than double. To be sure, in dry, desert-like environments, it's almost certainly not an issue, but at the seaside galvanic corrosion is clearly a problem. So the million-dollar questions are:
It seems to me, at least in the absence of certainty about the mechanics of the real-world process and conditions, we should err on the side of using consistent metal types for all components of a fixed anchors (because we know this eliminates galvanic corrosion). Of course this isn't always possible given what's in the pack, financial considerations, etc. But, "in a perfect world" we'd always match metal types in all environments. That is a conclusion I'll standby, because, even if we had perfect knowledge of the galvanic corrosion process in a lab, we have imperfect information about the real-world environments most fixed anchors will face. There is such a thing as better than good enough. |
Charlie S wrote: I fully understand that the hanger/stud metal combination is considerably more important. I have, throughout this discussion, maintained that it is better, ideal, a good idea, etc., but never claimed that it is necessary. I feel like you guys are projecting your prior "rubber sword fights" on me. If it isn't better, why do you say, "Matching metals is a good idea in general."? And why does Ken say, "Just use plated for a dry environment or stainless for a wet/humid environment (or titanium for tropical)."? You guys are arguing for acceptable, and I'm talking about ideal. They are different standards. |
James Schroeder wrote: What part of "It doesn't matter" are you having difficulty grasping? |
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And all of this blowback comes in response to my second after-thought in response to a person asking about lowering through anchors. So back to Edek's first question: Edek (if you're still reading), Avoid lowering through parts of fixed anchors that are difficult to replace. To facilitate that, carry a couple quick links in your pack. Ideally, if possible, match the metals of the hardware you're adding to that of the existing. Sub-note: If matching isn't possible, it's most likely not a huge deal, but if you're in a seaside or high-humidity environment, it's probably a good idea to either go back and fix the situation yourself, or if that's not possible, let locals know so they can fix it. |
Marc801 C wrote: The part where all of the info coming out dry Utah admits that it does, in fact, matter in some circumstances. You know where Ken, the now twice vouched for expert, says: Also, if it doesn't matter, why do all of you keep arguing? If it doesn't matter, why do all of you care if Edek carries stainless or plated quick links in his pack? Will that supposed error make the community more safe, less safe, or is it irrelevant? |
Charlie S wrote: But not in the climbing community. There are still a lot of myths, incorrect interpretations, skewed data, and folks who are just plain wrong and its all embedded right alongside the quality information. This is across forums on MP.com, Supertopo, etc. and also exists (although to a lesser extent) in reputable climbing publications and orginizations (Climbing, Rock and Ice, Access Fund, etc.). This applies to more than just galvanic corrosion as well. Outdoor crags also have some unique peculiarities that invalidate typical rules of thumb in the engineering world. I agree with Ken that galvanic corrosion from "mixing metals" on the exterior parts of the anchor (chain, rap ring, quick link) is nothing to be concerned about. However, each "link" in the exposed part of the anchor is going to have the exact same exposure to the elements. If the elements (ie general corrosion concerns) drive you to SS for one part, it should drive you to select SS for all parts. You should be matching metals for this reason. The possible exception to this is if you have a very popular route where you are wearing out the rap ring or quick links from rope wear much faster than from general corrosion. The idea being that in the name of saving money, you use a platted steel quick link for the rope end so its cheaper to replace it every few months/years but the rest of the anchor chain is SS to survive decades. This scenario is pretty rare so the rule of thumb would be to keep the same metallurgy across the anchor. |
Ken Noyce wrote: Ken, your science is off on this one. I can't vouch for why ClimbTech sells that tool, but damaging the protective layer on true stainless steel during installation is not a perfect spot for general corrosion to begin. Its true, manufacturers can use certain treatments to improve the protective layer before it leaves their shop (straight from Jim Titt). However, if you were to damage that layer during installation or during any other part of the hardware's life that protective layer (called a passivization layer in this case) will re-form during the natural oxidation of the metal surface. Stainless steel is "self healing" in this fashion. The passivization layer is mostly chromium oxide but is also made up some of iron oxide. Also, SS is still ~65% iron so depositing more iron from the hammer isn't going to change anything. The reason I say "true" stainless steel is the chromium content needs to be high enough for this passivization layer to be stable. The definition of SS usually starts at 10.5% chromium but even "low grade" SS (304/316) has at least 18% chromium. There is a decent amount of cheap/knock-off hardware out there that is falsely labeled as SS that is likely giving "true" SS a bad name in this case. I'll sheath my rubber sword now. |
James Schroeder wrote: And the sentence immediately before, which you didn't quote since it undermines your argument: "In 99% of climbing areas around the world matching metals between the hanger or glue in and quicklinks/rings doesn't matter at all."
We, well, I sure don't care what's in Edek's pack. The reason people keep arguing with you is that you've now become far more intent on winning an internet semantics argument than you are with getting accurate info into the hands of the climbing community. |
Mike Slavens wrote: Sorry, but my science is not incorrect, you have some correct information here, but you seem to have missed parts of my explanation (and if you want to ask Jim about it he will certainly corroborate what I am saying). You are correct when you say that if you damage the outer chromium layer of stainless it will self heal, the part you seem to have missed is when I pointed out that the non stainless tool that damaged that layer can leave iron from the tool on the damaged portion at the same time as doing the damage. This Iron that can be left inhibits the stainless from healing itself. That Iron then corrodes and creates a point where corrosion can begin on the stainless part. Edit to add: I didn't read your full post I guess before posting, but just to clarify a bit. Obviously stainless steel is mostly Iron, it wouldn't be steel otherwise, however, because the elements are uniformly distributed throughout the metal having a minimum of 12% chromium (that's where stainless generally starts) allows the chromium to oxidize and form the passivization layer. If you damage that chromium oxide layer and cover it with a large chunk of non-stainless steel it is impossible for the chromium to oxidize underneath the contaminant. The chromium has no way of growing over this newly introduced contaminant, so the contaminant rusts, now as you pointed out, SS is still mostly iron, so that rust can continue growing into the iron within the SS itself since no passivization layer was able to form between the contaminant and the rest of the stainless steel. This is why climb tech wants you use stainless tool to install their stainless wave bolt, the stainless tool will still damage the chromium oxide layer on the bolt, but because the tool is stainless, any contaminants left on the bolt will also be stainless, so both the bolt and the tool will self heal. |
Marc801 C wrote: Yes, this. Even in a humid environment (which is what James seem to be hung up on) matching metals doesn't matter, all that matters is that you use something that isn't suceptible to corrosion, so you could use titanium on stainless which wouldn't be matched metal, but it also wouldn't corrode. Stop trying to twist what I said because as I have said over and over, matching metals in this case absolutely doesn't matter regardless of it being a humid environment or not. |
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I am still reading. This has evolved into quite a discussion. As an update for the specific situation, I messaged the Ontario Hardware Fund (the dudes who keep track of and replace a majority, if not all, of the hardware in Ontario, especially the crag at which I encountered this situation), and he's looking into stainless quick links for those bolts. The route I climbed was a classic trad route (The Camel at Mt. Nemo) so to be honest I am not sure what other folks who have climbed this route have been doing all these years. I'm not a scientist or versed in any metallurgy to have an opinion, I just want to do the right thing and get a safe, durable anchor up on that route. |
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Here is a better explanation of why you use a stainless tool to place a stainless bolt, taken from https://www.polymersolutions.com/blog/why-does-stainless-steel-rust/ "Have you ever used a steel wire wheel or steel wool to clean off a stainless steel tool, and then the stainless tool rusted in the same spot which was brushed clean? Or have you seen a stainless steel container or sink rust? Stainless corroding in the absence of a corrosive element (such as chlorine) is usually from very tiny steel particles touching the stainless steel surface. Chromium can protect stainless steel if the localized concentration is in excess of 12%, but if you cover the stainless surface with sufficient steel particles, then the localized concentration of chromium can fall below the 12% threshold and the chromium oxide layer fails to protect the stainless steel from oxygen attack. If this type of corrosion happens to stainless steel, it is fixable by: (A) Cleaning off all the rust, and then (B) removing the tiny steel particles by thoroughly cleaning the stainless steel part, usually with a solvent. These two steps should allow the chromium oxide layer to protect the stainless from further oxidation." |
Marc801 C wrote: You've pegged me wrong, yet again. I am not trying to "win an internet semantics argument". Rather, I am trying to make the strong point, that when people are uncertain, they should err towards what they are certain about - or at least making mistakes that have no (or fewer) negative consequences. Not sure whether differing metals are bad? Use the same type of metal. Not sure if that nut placement is good? Assume it isn't. Can't tell if that hollow-sounding, but not moving block, is good? Assume it isn't. Not sure if you know how to thread the anchors properly? Don't start up the route, or send someone who is sure. This is a baseline for risk management whether in fixed hardware, any other climbing situation, or in broader contexts beyond the climbing world. Forgive me for not being 100% certain when it comes to mixing metals, but I'm not, despite what 3 dudes who have yet to present any hard evidence of the research, or their own credentials for that matter, say. You might all be right, but then again, I have very little evidence for that, and until I do, I'm going to stick with what I am certain is correct, or in the worst case, if I am wrong won't damage me or the broader community one iota. To be clear, you guys (Ken, Alexander, and Marc) are arguing that it doesn't matter. Some folks argue that it might. If that's the case, then what harm is there in erring towards what is a more comprehensive solution? Let's assume there are two variables each with two states. You guys are right - it doesn't matter, you guys are wrong - it does matter. Community uses matching metals, community doesn't. Given this there are four potential combinations each with its own success value.
Further, Mike Slavens makes an excellent point, which I haven't been thoughtful enough to express yet: This is certainly the strongest argument for matching the metals. If the original developer thought it was appropriate to use X metal when putting in the hardware, people replacing small parts of the hardware ought to take that into strong consideration. Regardless, I'll go back to my statement that started this row: "In a perfect world you'd match stainless to stainless and plated to plated." Which is still true, regardless of galvanic corrosion considerations. It's not necessary, but better, even if just a tiny, fractional, microscopic bit. EDIT TO ADD: Of course, if you guys were somehow arguing that it was BAD, and not just "not better", then all of the excitement from your end would make sense. |
James Schroeder wrote: Yes, you are, because you finish with:
Which is essentially saying "There! I won!", despite the last 8 words of that sentence equaling "irrelevant". |
Marc801 C wrote: No, that's me saying, that it's irrelevant what you guys are saying, because even if you're right, it's still better to use the same metal. The best "mistake" to make is to think the group of you is wrong. That's risk management in a nutshell - making the best mistake. |
1. We aren't arguing, we (mostly Ken and Marc) are explaining the applied science behind why it doesn't matter. 2. There isn't any harm, except to your wallet. It's your money, you are free to do what you want with it. Just don't expect other people to do so, because it is completely unnecessary. |
