Skip to main content

The Test UIAA in a nutshell, 7 things that every climber should know

Aimed for all.

Part 3 / 3
The Test UIAA in a nutshell, 7 things that every climber should know

1️⃣ The decision criterion

The decision criterion is based on the observation of a constant link between a specific environmental circumstance, a specific alloy composition and the pitting "phenomenon".

2️⃣ The experiments

Specifically, the UIAA team examined bolts from the widest possible range of rock walls, and for each anchor examined

  1. The alloy composition
  2. The minerals deposited on the anchors (from the rock in which the anchors were fixed)
  3. the composition of he rock in which the anchors were fixed
  4. The morphology of the surrounding environment.


Calcium Sulphate
Calcium Sulphate
from web

3️⃣ The results

The results of the experiments show two common circumstances in all the anchors affected by the pitting phenomenon:

  1. The steel alloy was for all classifiable as A2 (different from A4).
  2. The presence of sulphate traces (Sulphates are salts in which a sulfur atom is bounded to four oxygen atoms) on all the A2 steel anchors affected by the pitting phenomenon


4️⃣ The difference  between stainless steel A2 and A4

To put it as simple as possible: the stainless steel l’A4 is an A2 “spiked” with a 2.5-3% of molybdenum, to achieve a better corrosion resistance.



A2 vs A4
A2 vs A4: note the inscription A4-80
on the nut.
On the A2 nuts, instead,
there is A2-70
from web

5️⃣ Distinguishing at a glance between stainless steel A2 and A4

We put this question to Emanuele Pellizzari: “The only way to distinguish at a glance between the two consists in  reading the markings, that (as regards the expansion bolts) is written on the nut. Specifically: on the A2 bolts there is A2/70, whereas on the A4 there is A4/80 [cfr see the third pic n.d.e.].


6️⃣ UIAA Conclusions

Thus the UIAA commission

  1. Absolutely banned the use of stainless steel A2 in marine environment and anywhere outdoors.
  2. Recommended for all the marine rock walls a test to detect the presence of sulphates into the rock.


7️⃣ How to choose the anchors according to the presence of sulphate in the rock

  • If the results of the test indicate a percentage of sulphate greater than a  pre-set threshold, even if only in some points, titan anchors should be used. The usi of stainless steel is forbidden (whether it's A4, or A2, or HCR).
  • If the results of the test indicate a percentage of sulphate lower than a  pre-set threshold, instead, stainless steel A4 or Her can be used, but you need to carefully monitor the behavior of the anchors.
Part 3 / 3

Leave a comment

Plain text

  • No HTML tags allowed.
  • Lines and paragraphs break automatically.
  • Web page addresses and email addresses turn into links automatically.