Old BD Biner Pull Test

I was messing around in the engineering lab today, and brought in an old BD oval carabiner to break with the tensile tester. I'm not sure how hold the carabiner was, but old enough that is was only rated for 18kN on the axis. I put it in the tensile tester, and maxed out the machine 3 times, at 8,800 lbs (40kN). The carabiner never broke. My test set-up picture is below. I realize that I am not loading in the basket section of the oval, but loading closer to the spine because I was limited by the machine fixtures. Still, it was surprising that it didn't fail even at 2.2 times its rated strength.

I would expect it to fail at a lower load if it were tensioned in the "basket" section, as you referred to it. If you were able to pull test where the carabiner and runner rest (a hook attachment to the tester?), that would represent a more realistic test.

Edit: Maybe you could clamp a shackle at each end of  the tester, then pull test the biner?

It looks like the pull in the photo is mostly tensile loading of the spine. In the climbing situation, the rope load is aways applied a little ways away from the spine and adds a torque/shear on the spine. A D carabiner or a carabiner with a rope well will keep the rope closer to the spine, thus reducing the torque and increasing the maximum load (relative to a similarly constructed oval carabiner).

John Wilder wrote:

I believe the pull test for a carabiner is with a 10mm pin through the basket on either side. Try that, and I'd expect it to fail around 18kn.

Precisely. The test in the OP is not realistic to any scenario in which the carabiner would be used in. The UIAA mandates the test is completed with 10mm pins. Below is an example, just replace the sling with a carabiner.

"Gear testing video" thread I put in this forum has the real thing. Lots of exploding biners, including being bent sideways.

Sorry I don't know how to link to that on my phone.

Best, OLH

Alex Zucca wrote:

I was messing around in the engineering lab today,

As you noted you were messing around and not doing anything all that productive other pulling testing a piece of aluminum 6060 of which the results have no bearing on the reality of how it is used with carabiners.

On a more serious note, if you want to learn something about destructive testing, research the UIAA guidelines.

Allen Sanderson wrote:

As you noted you were messing around and not doing anything all that productive other pulling testing a piece of aluminum 6060 of which the results have no bearing on the reality of how it is used with carabiners.

On a more serious note, if you want to learn something about destructive testing, research the UIAA guidelines.

Why so demeaning? I was just posting something I thought other people would find interesting. No need to be rude here.

will my chouinard that's rated to "4000lbs" still hold a whipper? What if I only use it to rack tricams (which I forget to carry anyway)

Alex Zucca wrote:

Why so demeaning? I was just posting something I thought other people would find interesting. No need to be rude here.

Alex, I'm like you, if I had the opportunity I'd do the same thing! Nothing at all wrong with being curious, so long as you don't actually set the place on fire. My hubby's parents were scientists at NIH when he was a kid, and the geniuses there (literally geniuses) were smart enough to let the kid have access to all sorts of stuff, with a few guidelines ("don't do this. It explodes"). He loves chemistry to this day.

Thanks for your post!

Best, OLH

Allen Sanderson wrote:

As you noted you were messing around and not doing anything all that productive other pulling testing a piece of aluminum 6060 of which the results have no bearing on the reality of how it is used with carabiners.

On a more serious note, if you want to learn something about destructive testing, research the UIAA guidelines.

If we're going to be picky... Pretty sure BD uses 7071 aluminum ;-)

Next time you get the chance, see if you can figure a way to load just the gate side of the biner. 

Fun with science and expensive toys

Is anyone else surprised that those jaws held on at those pressures? Did they gouge in pretty deep?

They did bite into the metal pretty good. Only surface dimples, no gouges.