Winter is basically here and it’s the time of year when people start heading off on climbing trips to warmer climes…particularly popular are those dreamy, tropical oceanside crags in Thailand, Vietnam, the Dominican Republic, etc. But before you go trusting those bolts and anchors, BEWARE! Following recent accidents, the UIAA (International Mountaineering and Climbing Federation) released a warning about the risks of (stainless steel) anchor failure on bolted routes in tropical, marine environments.

In fact, according to the UIAA, first samplings from some climbing areas in tropical, marine environments showed that 10 to 20% of anchors could have a breaking strength as low as 1 kN to 5 kN! Just so you know, nominal climbing falls load anchors with forces of 1 kN to 5 kN. UIAA standards require fixed anchor strength to be a minimum of 22 kN.

From the UIAA website: “Overall, some fixed anchors broke bearing only the weight of a climber. And all examined were stainless steel, which meets the UIAA safety standard and has a reputation of holding up well against corrosion. The corrosion in this particular locale appears to be accelerated by the proximity of the sea and year-round warm, wet weather.”

Some of the anchors found had visible - yet sometimes hard to see - cracks. But check out these scary photos of anchors that showed no visible cracks but broke between 1 and 5 kN:


Here are the UIAA’s recommendations when climbing in tropical, marine environments:

  • Before any climbing, we strongly recommend that you enquire with the local climbers and/or with the local people who equipped the routes about the quality of the anchors in place.
  • Some areas are regularly re-equipped. If the bolts are less than 3 years old, experience to date suggests that the probability of finding a weakened anchor is low, even though bolt failure has been known to occur within 9 months of installation.
  • On the other hand, if you detect signs of rust on the anchors, this can indicate a badly weakened anchor. In that case, do not load the anchor, and retreat from the climb (experience from the field shows that some anchors would break when loaded with only the weight of the climber). Alert the local climbers/local people who maintain the climbing area, so that they can inspect and replace the weakened anchor. You could also replace the weakened anchor yourself—please replace the anchor with one of similar or superior corrosion resistance.
  • As a precautionary principle, we strongly advise you NOT to climb on routes in tropical, marine environments that show signs of rust on anchors and/or where you do not know either the person responsible for maintenance of the climbing area, or when the equipment was installed.
  • In the absence of reliable information about the integrity of anchors from the locals who maintain the bolts at a tropical, marine cliff, climbers must consider coastal, bolted routes as adventure terrain where all fixed anchors are questionable, as is the case in alpine climbing.
  • Ultimately, it is the climber him/herself who is responsible for his/her decisions and actions regarding the integrity of the anchors.


The UIAA has launched a full study of this problem and once it’s complete they will post the results on their website. For more information, read the UIAA’s full warning and the Safety Commission’s report (includes more photos of scary anchors).



The study by the UIAA is really eye-opening. Thank you Petzel for working with the UIAA to commission the study!

Thanks for the warning. I am

Thanks for the warning. I am not a climber because I have a severe fear of heights but my son and daughter love to do all this climbing and I worry about them. I don't know if they keep up with all the news around it and they'll probably groan when I show them this but if it will help them stay safe I'm all for it.

I just would not take any

I just would not take any risks with the anchors at all, it's not worth it.


In these areas where they can get an abundance of rain it's really easy for the anchors to get rusted like that. Talk to the people who put them up and make sure that they have regular maintenance. I've been on a couple trips to Vietnam and had to abort the last climb I was on because I just didn't trust the anchor system. Rusted out and not well taken care of. My solution, in the end, was to find an experienced person in the area to help you find the most reliable places to go.


Interesting Info

I hadn't really thought about this risk too much but what life-saving advice you have offered. I will pass it on to my rock climbing friends just in case they are not aware. Thank you.
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Superb info, many thanks! At

Superb info, many thanks! At 68, my climbing days are over but sometimes I still have to do some rope access work, so I like to keep up with what's what with the equipment--the climbing equipment is SO much more usable than the incredibly clunky OSHA junk!

Some highly pertinent questions: were these rusted anchors 400 series stainless steel (magnetic, heat treatable for higher strength, less corrosion resistant, can crack) or 300 series stainless steel (non magnetic, not heat treatable for higher strength but can be quite strong if work hardened (e.g., cold rolled sheet), highly corrosion resistant (expecially type 316, which is what should be used in a severe marine environment), not usually subject to cracking unless highly work-hardened), pr perhaps one of the precipitation hardening alloys like 17-4PH (magnetic, extremely strong, good corrosion resistance (commonly used in marine environments for snapshackles & other highly loaded components, but NOT as good as 304 or 316), has some ductility even in the hardened state so doesn't usually crack unless severely deformed in the hardened state).

An even more pertinent question: What grade of stainless steel are the Petzl anghors made of?



Our anchors are made of 316L quality stainless steel. Concerning the other questions we suggest that you get in contact with the UIAA commission that works on the topic.

Thank you for your interest.


rusting stainless steel

strange this rusting stainless steel. surely the ss used in maritime(naval)applications, the 316 quality as i understand, should resist salt water!!!!
expensive ss. parts on ships are expected to last more than 3 years!
if all ss. fails, maybe we should switch to titanium, of extreme corrosion resistance! koen

Corrosion of Stainless steel anchors

Koen is correct: 316 stainless will not corrode in seawater. But it's not ordinary NaCl (table salt) from seawater that's corroding the bolts.

Limestone dissolves in rainwater which runs down the rock, also picking up NaCl deposited by sea spray along the way. This runoff water then gets on the bolts, and especially behind the hanger. When the rain stops and the water evaporates, the Ca and Mg cations from the limestone combine with the Cl in the seawater to form both CaCl2 and MgCl2.

After several rain/dry cycles the MgCl2 (Magnesium Chloride) and CaCl2 (Calcium Chloride) become highly concentrated on the bolt. It is these high levels of Chlorides that are causing Stress Corrosion Cracking (SCC) at ambient temperatures in ALL Series 300 stainless steels.

I have no reports of SCC in marine Granite at this time. We have credible reports of SCC in marine Basalt, one from the Northern hemisphere and one from the Southern. Formal analysis will be done this summer.

Koen is also correct about titanium. Currently, Ti bolts are the only material proven to resist these conditions with 14 years of perfect service.

Anchor failure

In the above discussion of anchor failure I assume it is the bolts that are failing and not the hangers. This is because the photos presented above show hangers that, although showing evidence of corrosion, appear to be intact. Close up photos of the bolt fracture surfaces would be useful. Were the bolts expansion bolts or glued in with resin?
I think there are three points to answer:
1) Why are the 316 stainless hangers shown in the photos showing evidence of rust? I don't think this is typical of 316 but it would be of a carbon steel with a plated finish.
2) Assuming that it is the bolts that are failing and that they are 316 what is the corrosion mechanism? The bolt fracture surfaces could provide a clue.
3) Is there a better material for bolts and hangers? This would have to be equally strong, more corrosion resistant and cost effective.

This discussion thread is interesting to me as I am an offshore structural engineer and there has been a failure of a 316 fixed anchor on a sea cliff where I climb. This occured under the static weight of a climber and the cliff is a type of schist, not limestone.

RE Anchor failure

Hello Alan,

In fact it is both hangers and the bolts that are failing. For more details or discussions on this topic you can contact


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