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).


Stress Corrosion Cracking in Stainless Steel Anchors

Hello All,

What is happening here is called Stress Corrosion Cracking. There are many different forms and it can effect any type of metal metal if the conditions are correct. These conditions include, but aren't limited to: high temperatures, a preload (static load) on the anchor, and the presence of a corrosive element. In tropical marine environments we encounter all of these. The large seasonal swings in humidity play a role to accelerate the process as well as the hummic acid rich waters that permeate the limestone itself. Marine environments also can have high levels of magnesium salts which contribute to this problem with stainless steels.

one of the main difficulties, as pointed out above, is that it is impossible to adequately inspect the anchors. there may be little to no rust visible, but where the anchor enters the rock small cracks can penetrate through the entire bolt (perpendicular to the stress vector). Another issue is that the porosity and salt content inside the rock can vary greatly from place to place and so some anchors on a route may be affected whereas others are not. The bottom line is that stainless steel is dangerous in tropical marine environments.

How do we climb safely? The guys at Petzl make great points above. Additionally, glue-in anchors are safer by definition as there is no axial static stress. Unfortunately, this problem is inherently a material problem and some stainless steel resin anchors have still failed in the field. Without doubt, the Petzl Bat'inox and Collinox have shown them selves to be the safest stainless steel resin anchors used in Southern Thailand, but they have still failed in laboratory testing with the the same environment.

The solution that we have found to address this problem on the Pra Nang Pennisula in Southern Thailand (Tonsai) is using titanium resin anchors with a marine (impermeable) resin. Titanium is not subject to stress corrosion cracking under the same circumstances as 304 and 316 stainless steels. The anchors have proven safe in the field and in labs. Currently this is the best practice and is being done in several locations throughout the world. For more information check out Josh Lyons has made a great video on this dangerous issue and it is full of information. We are currently working hard to replace all of the anchors in Southern Thailand. Be educated, be safe, and I hope to see you in Thailand!

-Stephen Gladieux
Metallurgist and member of the Thaitanium Project

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