Stress Corrosion Cracking

Bob Mehew

Bob Mehew

Well-known member
BCA E&T has just got a report from BMC about a problem with chains used in an Climbing Wall anchor in Germany, see http://www.alpenverein.de/chameleon/public/da4c0207-b8d2-ac40-2fb8-6e4f172d99b0/techrock_warnhinweis_29_07_26208.pdf for a notice in English.  Whilst it does not look overly relevant to the UK set up, it would be useful to have a fluent german speak to improve on the Google translation of a related warning notice, see http://www.alpenverein.de/bergsport/sicherheit/fixe-umlenkung_aid_16119.html.  I would be grateful if someone could PM me with an offer.  Many thanks in anticipation. 
 
Joe90

Joe90

Member
If you haven't found anybody yet, my missus is a German lass.

Send me a message if you sill want it done.
 
Simon Wilson

Simon Wilson

New member
Interesting.

From the photos it looks like crappy steel and a crappy welding job.

It will be interesting to read a good translation.
 
O

Olaf

New member
The most important points I gathered from a quick read:

- It concerns fixed aids on *outdoor* climbing walls
- It appears that only the *last link* of each chain was affected, possibly because they were manually welded in place rather than the machine-welded other chain links
- However, the metal also showed some fissures *opposite* the welding spot, not just at the actual seam
- It is not yet clear, whether this also affects chains as shown in "Abbildung 4" in the website, i.e. where the chain is just a backup and not constantly under tension
 
Simon Wilson

Simon Wilson

New member
Olaf said:
The most important points I gathered from a quick read:

- It concerns fixed aids on *outdoor* climbing walls
- It appears that only the *last link* of each chain was affected, possibly because they were manually welded in place rather than the machine-welded other chain links
- However, the metal also showed some fissures *opposite* the welding spot, not just at the actual seam
- It is not yet clear, whether this also affects chains as shown in "Abbildung 4" in the website, i.e. where the chain is just a backup and not constantly under tension
Click to expand...

Welding stainless steel has to be done under very good quality control and is best avoided altogether if corrosion resistance is critical. I think the manufacturers will have taken this into consideration which is why they state that the item is intended for indoor use.

Since it was being used outdoors then it was not being used for the purpose it was intended for. I would expect that to be the first thing pointed out in the article. Does the article warn people to only use equipment outdoors if it is designed for outdoor use? 'Outdoors' includes caves - obviously (did you see what I did there?)
 
O

Olaf

New member
Techrock/Fixe does not state that it's for indoor use on their actual website. In fact they state "to be used in different areas (sport climbing routes, climbing walls...)": http://techrock.es/en/catalogo/productos/anclatges/desinox-v2-mosdracoinox2-plaq-d10mm/

The German website reads as if this was the gold standard anchor for outdoor use. No mention of it being used outside specifications or intended use area. Nevertheless, I don't think anyone is going to encounter one of these anchors in a cave.
 
Simon Wilson

Simon Wilson

New member
You're right but it does say it's for indoor use on this Fixe website.
http://www.fixehardware.com/shop/anchors/fixe-ss-3/8-draco-v-anchor/

The product appears to be made by Techrock and sold under their Fixe brand name.

The sentence about indoor use might have been changed after the corrosion problem was highlighted.

Fixe seem to be slightly vague about where it is to be used since it can also be found in every section of their website including the caving/canyoneering section.

I'm fairly certain we will never see one in a British cave but I know that Bob has a particular interest in stress corrosion cracking which I guess is why he wants to read a translation of the article.
 
Bob Mehew

Bob Mehew

Well-known member
I have one translator on the job and will come back at the weekend probably under a new thread in Equipment unless the mods transfer this thread with an amended title "- Stress Corrosion Cracking'.


[gmod]Done as requested.[/gmod]
 
Over the Hill

Over the Hill

New member
The Austrian Alpine Club in UK has thousands of UK members, they may be able to help more, there is a UK office (check the web).

If you need to understand some of the engineering side more I was caving only yesterday with another old lag who is the Forensic Engineering Lead (PHD) at a UK University and loves a challenge.  :coffee:
 
Bob Mehew

Bob Mehew

Well-known member
First apologies, this dropped of my to do list and I have only just found it again.  The topic will be discussed at E&T meeting on 15 November.  The line I will be pushing is no one is likely to be using this type of device so we can ignore the specific problem.  But there is a possible concern over 304 Stainless Steel which perhaps should be looked at.  The general position is you need three things for Stress Corrosion Cracking, presence of an aggressive ion (such as chloride), stress and temperature.  Given UK caves are well below the temperature threshold it perhaps is only a concern for steel work at the entrance.
 
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