Deep groove in carabiner?

[harness man]

Tom- to your earlier post:
our calculation for the grooving was for the total loss of material at the narrowest cross section of the groove.
To calculate we measured the thickness of the cross section at different angles, made a scaled drawing and compared to the original round cross section then used some basic math (and eye-ballin) to approximate the difference.
the calculations were conservative: the worst biners were probably a full third grooved...

[ratagonia]

Tom- to your earlier post:
our calculation for the grooving was for the total loss of material at the narrowest cross section of the groove.
To calculate we measured the thickness of the cross section at different angles, made a scaled drawing and compared to the original round cross section then used some basic math (and eye-ballin) to approximate the difference.
the calculations were conservative: the worst biners were probably a full third grooved...

Thanks for the clarification, and for putting in the effort to do a thorough job.



Tom

[harness man]

Thanks for your helpful comments
and thanks to nkanarik for starting this thread!
Best
Todd

[spinesnaper]

Todd

OMG! I am a 20 percenter. I am a 30% pretender.

Awesome to get real data. Thanks for the investigation.

I guess I will just keep retiring stuff when it looks funky.

Ken

[nkanarik]

Thanks everyone. I'm amazed what a deep discussion my simple question generated :)

[harness man]

nkanarik
While it may be a "simple" question you asked it is an IMPORTANT one we ALL have to ask: when is our safety equipment no longer safe?
spinesnapper
thanks for encouraging and contributing to the test- it helped a lot to have your samples.
Having a 20% or 30% 'notch' carved in a carabiner just LOOKS bad!
None of us would tolerate a 30% cut in a rope or sling- but carabiners seem to be a different animal...
More testing fun to come, surely...
How strong are those worn rappel devices?
How strong are old canyoneering ropes?
How strong are old harnesses (check your belay- loop lately?)
Best
Todd

[mcweyen]

Can we get a list of which carabiners are which in that list of tested biners?

[harness man]

Sure:
all the gold biners (B1, B3, B4, B5, B7) are Petzl Attaches.
The grey color (B2) is a Petzl William
The orange color (B6) is a Rock Exotica Pirate.
Please note that the breaking results we got do NOT necessarily demonstrate which carabiners are "stronger"- only that
loading this type of HMS carabiner further from the spine seems to lower the strength.
Note that the Rock Exotica Pirate has a higher listed strength (26 kN) than the others and it did well in this test.
Funny thing is we found that it seemed to wear out (develop grooves) faster than the Petzls.....go figure?!!
Best
Todd

[ratagonia]

Sure:
all the gold biners (B1, B3, B4, B5, B7) are Petzl Attaches.
The grey color (B2) is a Petzl William
The orange color (B6) is a Rock Exotica Pirate.
Please note that the breaking results we got do NOT necessarily demonstrate which carabiners are "stronger"- only that
loading this type of HMS carabiner further from the spine seems to lower the strength.
Note that the Rock Exotica Pirate has a higher listed strength (26 kN) than the others and it did well in this test.
Funny thing is we found that it seemed to wear out (develop grooves) faster than the Petzls.....go figure?!!
Best
Todd

"Funny thing is we found that it seemed to wear out (develop grooves) faster than the Petzls.....go figure?!!"

a good example of the saying: "the plural of anecdote is not data".

The Petzl Attache biners are made from the same stock on the same machines in the same factory at the Rock Exotica Pirate. There may be some variation in the batches of material (unlikely) and in the heat treatment (unlikely). More likely is that how they were used in the field was different.

Tom

[moab mark]

Excellent thread. Be interesting to see how many feet of rope wearing in the groove for one of the 30%ers to fail. Need some load on rope.

[Rob L]

I'm sorry, did I miss the part where someone said that none of the breaks were at the rope wear groove?

Rob

[spinesnaper]

I'm sorry, did I miss the part where someone said that none of the breaks were at the rope wear groove?

Rob

The engineers can jump in here. But yes, even the grooves leaving only 70% of the biner did not weaken the biner. So we are retiring this gear with still a vast safety margin. For me, that's ok. I like buying new gear. A nice shiny biner on the harness is just one less thing to worry about. On the other hand, if you are out there in the field and seeing some daylight in your biner, no reason to fret, it is going to support your body weight. I suspect that the engineers would also remind us that this was a small sample, your milage may very, and things are closer than they appear in the mirror.

Ken

[harness man]

Hey Ya'll
Rob, you can see on the group photo on page 2 all the broken carabiners have the groove/pull point at the bottom marked- and you can see the breaks were mostly low on the spine.
Agree completely with Tom about anecdote making POOR evidence!
Thing is, Desiree (115 lbs) on a new Pirate, and Todd (145 lbs) on a new Attache, both using CRITRs in all the same canyons, swapping first person down/ LAPAR and she saws thru her Pirate first....but why?
I had also assumed that the raw aluminum stock is IDENTICAL for the two biners since they are both made at the same
Rock Exotica factory.
Have to as Rock (the owner) about this one.