# Steel vs Aluminum



## PinnaclePete (Feb 7, 2011)

Here's an example of what happens to steel and aluminum carabiners when subjected to overload. The steel biner is rated at 24kN (5,400 lbs.), the aluminum rated at 25kN (5,625 lbs.). Obvious that steel bends and aluminum snaps, both failed without warning. FWIW, the rope used in each did not break. These biners were brought in by customers, so I don't have exact failure factors. Thought it might be interesting.


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## 2dogs (Feb 8, 2011)

I can't believe they failed "without warning" if they were used as intended and within their limits. There is no way a biner used in climbing would be subject to over 5K pounds pull. Were these biners used as rigging? Maybe towing out a stuck truck? 

More info please.

BTW, nice pic.


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## PinnaclePete (Feb 8, 2011)

2dogs said:


> I can't believe they failed "without warning" if they were used as intended and within their limits. There is no way a biner used in climbing would be subject to over 5K pounds pull. Were these biners used as rigging? Maybe towing out a stuck truck?
> 
> More info please.
> 
> BTW, nice pic.


 
Exactly the reason for this forum. The biners were not used (at the time of failure) for climbing.

The non-locking steel biner was used to suspend a pulley in a removal and shock loaded. The aluminum Petzl was used to try and (static) pull a utility pole out of the ground during an ice storm.

Anybody else have pictures and stories.


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## ozzy42 (Feb 12, 2011)

PinnaclePete said:


> Here's an example of what happens to steel and aluminum carabiners when subjected to overload. The steel biner is rated at 24kN (5,400 lbs.), the aluminum rated at 25kN (5,625 lbs.). Obvious that steel bends and aluminum snaps, both failed without warning. FWIW, the rope used in each did not break. These biners were brought in by customers, so I don't have exact failure factors. Thought it might be interesting.


 
If nothing else ,this is a reminder to use all life supporting equipment at 1/10th or less of it's breaking strength,,,,as reccomended.

andFWIW
A 5000lb pull on a saddle would likely crush a climbers spine,so the failure would be of small consequence.















of it's breaking strehgth,,,,,as reccomended.


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## treemandan (Feb 13, 2011)

PinnaclePete said:


> Here's an example of what happens to steel and aluminum carabiners when subjected to overload. The steel biner is rated at 24kN (5,400 lbs.), the aluminum rated at 25kN (5,625 lbs.). Obvious that steel bends and aluminum snaps, both failed without warning. FWIW, the rope used in each did not break. These biners were brought in by customers, so I don't have exact failure factors. Thought it might be interesting.


 
Both of those beeners look to be ali. And they both look to be used inappropriatly .


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## treemandan (Feb 13, 2011)

2dogs said:


> I can't believe they failed "without warning" if they were used as intended and within their limits. There is no way a biner used in climbing would be subject to over 5K pounds pull. Were these biners used as rigging? Maybe towing out a stuck truck?
> 
> More info please.
> 
> BTW, nice pic.




I don't either.
You want more info? Sure! They got broke cause they were used for what they shouldn't be by an mo-ron. And I have seen plenty of guys go hucking weight onto those things. If anyone got hurt my sympathy would go to the beeners.


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## HeritageTree (Apr 16, 2011)

Improper use sums that up! Aluminum or steel doesn't matter.


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## Groundman One (May 15, 2011)

HeritageTree said:


> Improper use sums that up! Aluminum or steel doesn't matter.


 
Hence, the *Big Dan*. 






Never leave home without it.


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## VA-Sawyer (May 16, 2011)

I have no problem trusting Aluminum. I have been trusting it my whole life. I starting flying before I started driving. ( Dead True )

I just treat my aluminum gear carefully to avoid letting it impact against other hard things. I inspect it often for stress risers and retire any that takes a hard hit on a hard surface. 

Aluminum and alloy steel both tend to become more brittle as the hardness increases from heat treating or work hardening. The difference is one tends to need to push the hardness in aluminum closer to the strength limit in order to obtain the needed strength. This puts it closer to the brittle point than a steel part needing the same strength. The aluminum part will be lighter than the steel one and that can be an important point in climbing gear as well as flying machines. We just have to remember the trade off is the aluminum part will require better treatment and inspection in exchange for that lightness.
Rick


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## bomar (Jun 3, 2011)

hopefuly no one got hurt but ya i agree with dan thers no way those wer being used properly because if they were loaded with a rope that rope would break first especialy if it had a knot tied somewhere on it


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## barton174 (Jun 22, 2011)

PinnaclePete said:


> Exactly the reason for this forum. The biners were not used (at the time of failure) for climbing.
> 
> The non-locking steel biner was used to suspend a pulley in a removal and shock loaded. The aluminum Petzl was used to try and (static) pull a utility pole out of the ground during an ice storm.
> 
> Anybody else have pictures and stories.


 
Do these people know that they make stuff made just for this kind of thing, that's rated much higher? Amazing... This is why you don't buy used climbing gear... You never know what somebody has done with or to it...

Mike


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## Ghillie (Jun 29, 2011)

Was the key-lock portion of the non-locking caribiner deformed? As in, was the gate closed when it was loaded?


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## gwiley (Jun 29, 2011)

I do a fair bit of welding in addition to my tree work. Based on chatter on what I hear from other metal workers most aluminum alloys do not do well when subjected to forces cause even mild deformation - leads to fatigue related failures. Steel is much slower to develop fatigue related failures. If you are prone to pushing the limits on your gear it is a better idea to go steel (although even better to make more of an effort to work within the specs).


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