06-15-2014, 09:38 AM #1
Metal fatigue test pull of a out of service Croll
I pull tested this Croll to see what the force to failure would be at that connection point (to give an idea of what it would be at the main connection point). This Croll was taken out of service for obvious reasons after being in an offshore environment for a period of time (unknown to me how long). The upper was connected via a short Dynema sling that held salty moisture and would rum while being used. To me this was the cause for such damage. The pull test results are as follows:
Croll connected to hard anchor with a 5:1 MA pulling the opposite connection point. Temp was 61 degrees F, low humidity at about 200 ft above sea level (roughly). Slow pull to failure.
Failed at 114 lbs of force ( .51 Kn or 51.8 Kg).
From my understanding Petzl makes their equipment from a 7075 aluminum that is very strong!
So this goes to show how with some corrosion it can take strength away fast. Although this is a bit more then a little corrosion.
06-15-2014, 11:04 AM #2
- Join Date
- Jul 2006
- Southern Illinois
Salt environment is definitely hard on metal. Although, had this failure occurred in actual use, the user would still be in suspension, as the lower hole is the primary connection. The upper hole simply allows one to lean back and engage the upper half of a class 3 harness so as to rest the abs. For those of you who aren't familiar with how a chest ascender works...
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