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Chockstone Forum - Accidents & Injuries

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biner breaks on Forever Young 12-Dec-2011 At 9:34:20 AM Climboholic

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I am also an engineer and I think people are making too many assumptions to come up with a reliable explanation of what happened. A failure like this could have serious consequences and it is worth while figuring out the facts.

The anecdotal evidence from the climber that there was “absolutely no take in the rope when I heard a snap” is completely unreliable. Firstly, this is physically impossible (and if a very low load there is more going on than just torsional failure). Secondly, the failure would be almost instantaneous so the climber wouldn’t notice (spline looks like brittle fracture (btw, how cold was it?)). Thirdly, there is too much going on in a fall for the climbers account to be reliable anyway.

From the photo there are clearly 2 failure surfaces; one on the main bulk and the other on the spline. This could be consistent with torsion failure but possibly also with fatigue if there are striations. We could tell better if there was a close up picture of the failure.

The point made by pecheur that it wasn’t bending failure because of where it broke isn’t necessarily correct. I’ve tested biners to failure with design load (bending) and they’ve broken in the same place. Fatigue is possible if the biner had an indentation from a heavy fall on a fixed hangar which could act as a crack nucleation point.

I suggest either sending the failed biner back to the manufacturer or sending it to someone like Mikl (who I believe is a Materials Engineer), to figure out exactly what happened.