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WARNING: 370 lb breaking strength lower offs
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miklaw


Mar 10, 2009, 6:27 PM
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WARNING: 370 lb breaking strength lower offs
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This biner was removed from the top of "These People are Sandwiches" at Shipley NSW Australia. It was a single point lower off and looked like a nice stainless wiregate. An eagle eyed climber saw a fine crack (possibly it was more open under body weight) and retired it. At this point it looked like a standard bent wire biner with an unnecessary weld in it.

I was eager to see if there was a weld defect that caused the crack, so broke it in gate open mode to try and preserve the fracture surface.
It broke at 169 kg (372 lb). Wow.

The strength with the gate closed is difficult to estimate, the gap between the wire gate and notch was 3.5 mm, under load the gate must have engaged otherwise it probably would have broken in use. Lets assume the unit would have held twice the breaking load or 338kg or 744lbs.

On inspection it was cast and had a shrinkage defect in it (across about 30% of the shaft). The edges of the defect were probably fused closed and thus looked ok when it was new, they appear to have torn under use. There was a dimple at the end of the crack (just visible) showing some plastic deformation. After sectioning a number of other things were observed.
1) The significant corrosion inside the crack was probably an ďoriginal sinĒ being high temperature oxides that formed in the hot tear during casting.
2) Amazingly there was a weld repair at one point also

What does this teach us?
Itís better to have redundancy, twin independent anchors
Be careful using non-climbing gear. Cast gear is particularly variable in strength, fatigue strength, toughness etc.
Attachments: IMG_9811s.jpg (45.5 KB)
  biner1.jpg (24.0 KB)
  biner3.jpg (56.5 KB)


adatesman


Mar 10, 2009, 6:40 PM
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miklaw


Mar 10, 2009, 6:44 PM
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Re: [adatesman] WARNING: 370 lb breaking strength lower offs [In reply to]
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No markings anywhere, just a number 10 on it (diameter in mm?)
A local has been rebolting and shelled out his hard earned for these, they look bomber, not unlike the nice Fixe product, but are obviously very much weaker.
Thanks for posting the photos


Partner angry


Mar 10, 2009, 6:49 PM
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Re: [miklaw] WARNING: 370 lb breaking strength lower offs [In reply to]
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Do you know the intended purpose? If they're not climbing gear, I don't really know what they are.


miklaw


Mar 10, 2009, 6:53 PM
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Re: [angry] WARNING: 370 lb breaking strength lower offs [In reply to]
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marine accessory biner?
clipping dog/child to leash/ back of pickup?
clipping waterbottle to pack?
I don't know, but there appears to be a market for them.


Partner angry


Mar 10, 2009, 7:04 PM
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Re: [miklaw] WARNING: 370 lb breaking strength lower offs [In reply to]
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They just look a lot beefier than the toy stuff. Even an old retired biner would be better.


miklaw


Mar 10, 2009, 7:14 PM
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Re: [angry] WARNING: 370 lb breaking strength lower offs [In reply to]
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Agreed, any old climbing biner would be better. We will have a posse replacing these ASAP.

I mostly posted this result as the low strength (because they were cast) surprised (and terrified) me, and I was concerned that they may be available in the US. I still haven't found where they came from


(This post was edited by miklaw on Mar 10, 2009, 7:37 PM)


rschap


Mar 10, 2009, 7:32 PM
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Re: [miklaw] WARNING: 370 lb breaking strength lower offs [In reply to]
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I repair cast (alum, ss, steel) all the time at work, itís brittle, very brittle. I would think one hard hit against the rock would be enough to fracture it. Beaners need to be rated or theyíre only good for holding up your chalk bag.


bill413


Mar 16, 2009, 7:47 PM
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Re: [rschap] WARNING: 370 lb breaking strength lower offs [In reply to]
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Man, that's scary. i do wonder what the intended purpose of these biners was.


acorneau


Mar 16, 2009, 8:02 PM
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It looks a lot like the Wichard biners (made for marine/boating purposes), although this one is welded so I can't be sure:

http://


billcoe_


Apr 18, 2009, 11:20 AM
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Re: [acorneau] WARNING: 370 lb breaking strength lower offs [In reply to]
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In either case: as they seem to look good (before they break:-) , I speak for all of us, and thank you for the heads up Mikelaw.


maldaly


Apr 18, 2009, 1:16 PM
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Re: [billcoe_] WARNING: 370 lb breaking strength lower offs [In reply to]
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I'm astonished that you think that is cast. Why do you think so? Of all the methods for forming metal to make a carabiner, casting would be on the bottom of most people's list, including mine.

The design is modeled after the Wichard marine hardware carabiner. Wichard products are very well made, extremely strong and quite pricey. The Wichard 'biner of that shape is cold forged (bent) and welded. Rich sailors use them to moor their $20M sailboats. West Marine currently lists that model for $37.99 All Wichard products are marked with a "W".

I've seen some Chinese versions that sell for less than $12 that are only marked with a numeral indicating the diameter of the stock. In this case, 10mm.

Choose your gear carefully,
Mal


reno


Apr 19, 2009, 2:50 AM
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Re: [miklaw] WARNING: 370 lb breaking strength lower offs [In reply to]
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miklaw wrote:
It was a single point lower off

Kinda surprised nobody mentioned that little tidbit yet.


scrapedape


Apr 19, 2009, 6:38 AM
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Re: [reno] WARNING: 370 lb breaking strength lower offs [In reply to]
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reno wrote:
miklaw wrote:
It was a single point lower off

Kinda surprised nobody mentioned that little tidbit yet.

miklaw wrote:
What does this teach us?
Itís better to have redundancy, twin independent anchors


erick


Apr 19, 2009, 6:57 AM
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Re: [miklaw] WARNING: 370 lb breaking strength lower offs [In reply to]
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dang. thats pretty effed up.


miklaw


Apr 19, 2009, 5:46 PM
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Re: [maldaly] WARNING: 370 lb breaking strength lower offs [In reply to]
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maldaly wrote:
I'm astonished that you think that is cast. Why do you think so? Of all the methods for forming metal to make a carabiner, casting would be on the bottom of most people's list, including mine.

I agree casting would the last option for strength and reliability, but it is cheap. Why do I think it's cast?
1. Fracture appearence showing both a high temperature (oxidised) defect and dendritic structure.
2. Metallrgical examination showed large dendritic cast structure very similiar to ASTM standard cast structures.
3. Independendent confirmation by a (45 years experience) metallurgist
4. Presence of weld repair of a large defect, proabbaly autogenous with a TIG torch, the grain size in this was less than 1% as big


rschap


Apr 20, 2009, 5:08 PM
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Re: [miklaw] WARNING: 370 lb breaking strength lower offs [In reply to]
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Iím astonished that you quoted the post without adding anything to it, thatís almost as good as the second poster in the thread quoting the original poster like we donít know who they are responding to.


(This post was edited by rschap on Apr 20, 2009, 5:09 PM)


notapplicable


Apr 20, 2009, 5:28 PM
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Re: [rschap] WARNING: 370 lb breaking strength lower offs [In reply to]
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rschap wrote:
Iím astonished that you quoted the post without adding anything to it, thatís almost as good as the second poster in the thread quoting the original poster like we donít know who they are responding to.


desertwanderer81


Apr 22, 2009, 1:41 PM
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Re: [miklaw] WARNING: 370 lb breaking strength lower offs [In reply to]
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miklaw wrote:
This biner was removed from the top of "These People are Sandwiches" at Shipley NSW Australia. It was a single point lower off and looked like a nice stainless wiregate. An eagle eyed climber saw a fine crack (possibly it was more open under body weight) and retired it. At this point it looked like a standard bent wire biner with an unnecessary weld in it.

I was eager to see if there was a weld defect that caused the crack, so broke it in gate open mode to try and preserve the fracture surface.
It broke at 169 kg (372 lb). Wow.

The strength with the gate closed is difficult to estimate, the gap between the wire gate and notch was 3.5 mm, under load the gate must have engaged otherwise it probably would have broken in use. Lets assume the unit would have held twice the breaking load or 338kg or 744lbs.

On inspection it was cast and had a shrinkage defect in it (across about 30% of the shaft). The edges of the defect were probably fused closed and thus looked ok when it was new, they appear to have torn under use. There was a dimple at the end of the crack (just visible) showing some plastic deformation. After sectioning a number of other things were observed.
1) The significant corrosion inside the crack was probably an ďoriginal sinĒ being high temperature oxides that formed in the hot tear during casting.
2) Amazingly there was a weld repair at one point also

What does this teach us?
Itís better to have redundancy, twin independent anchors
Be careful using non-climbing gear. Cast gear is particularly variable in strength, fatigue strength, toughness etc.

What scares me is that people have apparently been rapping of this carabiner for quite some time.

Shame we can't find out who actually put this carabiner on the climb.....


kachoong


Apr 22, 2009, 1:53 PM
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Re: [desertwanderer81] WARNING: 370 lb breaking strength lower offs [In reply to]
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desertwanderer81 wrote:
Shame we can't find out who actually put this carabiner on the climb.....

Welcome to Oss-Tray-Ya! Wink


desertwanderer81


Apr 22, 2009, 2:00 PM
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Re: [kachoong] WARNING: 370 lb breaking strength lower offs [In reply to]
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As long as they're not placing that junk in MY country :P


mikes


Apr 23, 2009, 7:08 AM
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looks like a material imperfection located close to he weld. The material properties could have been changed more than they should have been by rapid quenching. The combination of a possible existing material flaw and a drastic change in the material properties combined with the play between the nose and the wire gate could cause a superficial crack to propagate into a visual crack. Considering the amount of bending caused every time the biner is loaded.


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