Safety factor on Carabiners

[Jamie]

I was just looking at my Petzl catalog and I notice the Owal oval carabiner is rated at 24 kN. Does that mean you might expect it to fail around there, or is there a safety factor so 24kN is like a working load and there is no problem using it at its limit? If there is a safety factor what is it? x2? x3? etc...

Just curious.

[genepires]

i would like to see how you can get any normal situation to reach 24kn on a biner. I forget the actual numbers, but I thought a fall factor 2 was the most force achieved while climbing and that resulted around a 16kn force.

[G-spotter]

I was just looking at my Petzl catalog and I notice the Owal oval carabiner is rated at 24 kN. Does that mean you might expect it to fail around there,

 

yes

[johnsonjj22]

Check out this: http://www.dmmclimbing.com/video.asp?id=5 to see nylon/dyneema runners fail and at what load. A fall factor of 1 (distance of half the length of the runner) on dyneema generates 23kn of force. The Owal oval 'biner might be okay, but I've seen oval 'biners rated at 18kn.

[selkirk]

i.e. falls on static cord are very bad.

 

Falls on Dynamic cord (even factor 2) not so bad.

[kurthicks]

BD Quality Control

 

3 SIGMA

 

ISO 9001

To rate our climbing gear with a meticulous degree of accuracy, Black Diamond uses a rigorous, best-in-the-industry rating standard called Three Sigma. By batch testing our climbing equipment following 3 Sigma methodologies, we can ensure that there is a 99.87% probability that the strength of any item taken from the same batch will be above the rating. And though the rigorous 3 Sigma testing method results in a rated strength that is three standard deviations lower than the average value found during testing, we feel climbing hardware requires testing with an absolutely consistent and conservative approach to ensure the high levels of quality you have come to expect from Black Diamond.

[lancegranite]

Industrial carabiners have a safety factor, usually 5:1.

Recreational carabiners have a breaking strength, the listed number is 'it'.

[G-spotter]

By batch testing our climbing equipment following 3 Sigma methodologies, we can ensure that there is a 99.87% probability that the strength of any item taken from the same batch will be above the rating.

 

Given that they don't tell you the width of the sigmas, all this means is that the breaking strength of your 24-kn-rated biner could be 24.01 kn

[kurthicks]

but they do, if you remember statistics!

 

"3 Sigma testing method results in a rated strength that is three standard deviations lower than the average value found during testing"

[stevetimetravlr]

Try and break a dyneema sling by jumping off above the anchors and falling full impact onto the sling. Won't happen. You won't break the biners either, but your back might not like it.

[G-spotter]

but they do, if you remember statistics!

 

"3 Sigma testing method results in a rated strength that is three standard deviations lower than the average value found during testing"

 

Well but what distribution do those three sigmas follow?

 

In other words for the same mean you can have two different standard deviations. High Cv = high sigma relative to mean and vice versa.

[kurthicks]

it's true, it does depend on the alpha value (if i can dig back into my stats class in the back of my brain). enough discussion about it though...

 

you'll only break them if they're loaded over an edge or have an open gate, if used in a climbing application.

[Jamie]

Thanks kurthicks.

I'm that is quite helpful. I'm a safety consultant and sometimes have to evaluate the likelihood of climbing gear failing. Of course the cause of accidents is much much more likely to be human failures (unsafe acts) rather than equipment failures (unsafe conditions).

 

Edited October 15, 2014 by Jamie

[Jason4]

i would like to see how you can get any normal situation to reach 24kn on a biner. I forget the actual numbers, but I thought a fall factor 2 was the most force achieved while climbing and that resulted around a 16kn force.

 

Won't a tight slackline get close?

[Jason4]

i would like to see how you can get any normal situation to reach 24kn on a biner. I forget the actual numbers, but I thought a fall factor 2 was the most force achieved while climbing and that resulted around a 16kn force.

 

Won't a tight slackline get close?

[tvashtarkatena]

Yes, a tight slackline can exceed 24kN when weighted.

 

Biners rarely fail, but they do come unclipped from bolts if not properly oriented on quickdraws - as they very often aren't. Don't oppose the gates on your quickdraws. Face both gates the same direction:

 

Linky