In reply to Peter Herold:
L&G,
Sorry for the slow reply to this thread, but I wasn't a member of this forum before.
I'm the South African Delegate to the Safety Commission of the UIAA. And I'm a materials engineer. Plus I'm on the Working Group that's working on the revision to the UIAA Anchor Standard 123.
We're aware of various failures to anchors, caused by a number of mechanisms. The one that has got the most discussion in the past 5 years has been chloride stress corrosion cracking (SCC) but there are other failure modes that are just as serious.
We did a survey of anchor failures and found that as many as 20% of anchors in some hot/tropical locations had suffered either cracks or severe corrosion. Some of these failures are very likely due to SCC. Without a detailed individual metallurgical analysis we cannot say exactly how many were due to SCC, and how many due to other corrosion causes. But many have cracks that are characteristic of SCC. And these problems are not restricted to hot/tropical areas either, altho the incident rate in other areas is lower.
And looking at the photos of the failed anchors reported on the Italian site in this thread, it seems to me that SCC is a possible culprit:
http://www.planetmountain.com/News/shownews1.lasso?l=1&keyid=39611#
However, even if they aren't due to SCC, they are still failed anchors. And it's a problem.
We have re-issued our 2009 warning/caution in the UIAA Newsletter, see here:
http://www.theuiaa.org/news_375_Safety-Commission-issues-update-of-corrosio...
In addition, we will be posting updates of our work there in case you want to check again.
The overall issue of environmental degradation (i.e corrosion as well as SCC) of climbing anchors is not an easy subject to address. Not only is it a fairly complex technical subject, but the economics of bolting adds difficulty. Climbers, especially bolters, can tend to be quite short of money and are thus very cost conscious, altho they place little monetary value on their time. So the anchor selection process in climbing is done quite differently from in industry.
Plus there is usually no specified lifetime for climbing anchors, nor frequently any regular inspection and replacement system, unlike in industry. There are exceptions to this, but it tends to be done on an ad hoc basis.
We propose a three part solution to address these issues:
(1) Anchors be classified in terms of their resistance to corrosion and stress corrosion cracking
(2) Standard tests and requirements are identified to rate anchors according to these classes
(3) The UIAA issue some recommendations about what anchors to use where, and help pass on any other good ideas on how to address this issue
We believe that the following anchor classes would be appropriate:
Class 1: High resistance to both general corrosion as well as to chloride SCC
Class 2: High resistance to general corrosion and moderate resistance to SCC
Class 3: High to moderate resistance to general corrosion and no specified/required SCC resistance
Class 4: no specified/required resistance to corrosion or to SCC
We're still working on the best way to specify each class.
Class 1 is likely going to be anchors made from extremely corrosion resistant materials such as 904L, 254SMO and some titanium alloys.
Class 2 will likely be 316, perhaps only the 316L grade of 316. We need to think about that.
Class 3 is 300 and 304 grade stainless steel.
Class 4 is for indoors, altho swimming pool locations, if any, are a special case.
It's perhaps somewhat simplistic to characterize the anchor class just by the materials used to make them. However maybe that will work. It would be very nice if we can come up with a simple means to classify them.
So the idea is that when you buy an anchor, it will be designated as one of these classes by the manufacturer. And the end-user (you) will need to decide what class anchor to use where. That is going to be difficult to nail down in many cases, however we will all learn as we go on.
Please note that we are NOT going to try to "ban" any type of anchor, altho some types of material are known to cause problems, such as type 303 stainless steel. But in that case, it can still be given a class: in the case of 303, likely Class 4: indoor use only.
Also note that we see no fundamental problem with using thickly coated galvanized anchors, like the French use on the coast. Indeed, in many cases they have been used quite successfully. The issue with them goes back to what I said earlier tho. They do not tend to have a very long service lifetime, quite often under 10 years, and then need replacement. However when the galvanizing is either worn away, or is corroded, the underlaying steel starts to rust and this is usually quite obvious, and gives notice that they need replacement. So in effect, quite often they are "fail safe".
The problem by contrast with many 300 series stainless steels (like 304 and 316) is that when they start to crack/fail, it can be very sudden, and often there is no obvious warning beforehand.
But it is not our aim to try to tell people that all 300 series stainless steels are "bad" (300, 304, 316) just because of a relatively small number of failures. However they CAN fail, and are quite capable of causing serious injury or death. So we need a way to decide when 304/316 can be used safely and when it is not appropriate.
What we expect is that if climbers aim to bolt for longer times, say a 50 year lifespan, then they will want to use a higher class. And the initial greater cost of this anchor class will be substantially diluted by the longer lifetime. And the idea of a 50 year lifespan is not unreasonable: that's considered "normal" in the construction industry.
Please note that a lot of this is still a work-in-progress and we still need to get our detailed plans approved by the entire Safety Commission. However we presented these ideas at the latest meeting in St Petersburg and they were favourably received.
Anyway, sorry for the long email, but that's what we're working on. Your comments are welcome.
Alan Jarvis
MCSA Delegate to UIAA Safety Commission