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Myths Debunked 1: Discard a Dropped Carabiner

posted Mar 5, 2013, 11:55 PM by Ken Buscho   [ updated Feb 13, 2014, 9:47 PM ]
For as long as I can remember, there was a rumor that dropping carabiners was bad for them; it generated hairline cracks, and was a deathtrap waiting to happen.  Not.

Fortunately for all of us, there are folks out there who are have the credentials and are willing to take the time to actually research and test these things.  What follows is an excerpt from Geir Hundal's excellent site "The Climbing Mythbusters" (http://www.geir.com/mythbuster.html)
The picture on the left shows what it really takes to destroy hardware. And, as they say on TV, don't try this at home.  Read and enjoy.

From: The Climbing Mythbusters  (http://www.geir.com/mythbuster.html)

Myth 1: Carabiners are fragile  

Myth:  "Carabiners are susceptible to hair-line fractures if they are dropped. These fractures cannot be seen by the naked eye, but can drastically weaken a carabiner. So NEVER DROP YOUR CARABINER. If you do, it is best to discard it immediately and replace it with a new one."  (source: http://www.cbcnsw.org.au/docs/AbseilGuidelines.pdf)

Reality:  This is not true of modern carabiners.  First, the "grain" of the aluminum runs parallel to the stock, not perpendicular, so undetectable hairline fractures spontaneously causing carabiner failure just isn't true. Steve Nagode, a quality assurance engineer with REI, conducted an experiment in which carabiners were dropped six times from a distance of 10 meters onto a concrete floor.  The breaking strength of the carabiners was then determined with a 50-kN load cell.  The results:  no reduction in strength was observed when comparing the dropped carabiners with carabiners that had not been dropped.  

Black Diamond's website says this:  "It's best to inspect dropped gear for dings and significant trauma. If only light scratching is visible and gate action is still good, there is a good chance it is fit for usage."

Here's a more colorful test, this time done with a Petzl Reverso:  I call this "Reverso VS .357 Magnum". Shooting a small object with a snubnose .357 from a safe distance is tricky, but yields thrilling results.  This is akin to throwing the Reverso into a rock surface at 67m/s*, which would require dropping it 240m (790 feet).  And these calculations omit air resistance, which limits the terminal velocity of the Reverso free-falling to around 35m/s (the terminal velocity of a baseball).  In actuality, the piece of gear would not reach 68m/s even falling this far.  The Reverso bent various ways, but it took 5 direct hits before it actually broke.  This seems to indicate that a single, short drop for a piece of hardware does little to no damage.  


* 67 meters/second =149 miles/hour or 220 feet/sec (Ken)