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General Climbing Discussion

Topic Date User

biners never break :( 8-Feb-2005 At 10:17:50 PM AlanD

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On 8/02/2005 tonybro wrote:
>>Biners are aluminium alloy and the strength is derived from an artificial
>aging process, so the actual age of the gear is insignificant, in theory
>the older the better. However, age includes history and some shock loads
>may have induced weeknesses.

While I agree with your post generally, this bit is a bit misleading. The ageing process can be described by a bell shape curve (time vs strength). Generally the aim is to achieve the optimum (max) strength, so extra ageing beyond this would result in the loss of strength. However, the ageing process is normally down at elevated temperatures (somewhere around 130 - 170 deg C). Although room temperature ageing is possible in a few aluminium alloys it's generally so sluggish for most other aluminium alloys to say that no ageing has occurred. It's unlikely to be the alloys used for biners would be one that ages at room temperature.

Put me down as some one saying ductile overload caused by the position of the biner when the fall occured combined possibly with a small amount of previous abuse. A biners strength is not uniform, they have specific directions of strength.

But without looking at the biner, it's only guess work, it could be a manufacturing flaw that wasn't detected, such as an inclusion in the metal. Non destructive testing want detect every flaw, just the obvious ones that are being looked for.