Southern Yosemite Climbing Discussions
Southern Yosemite Categories => General Discussion => Topic started by: mungeclimber on March 23, 2015, 10:19:07 am
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http://www.safeclimbing.org/education/fallforces.htm
Toprope falls develop lower impact forces, but can still load the anchors as much as mild leader falls. In live drop tests using a dynamometer to measure peak loads, we generated over 1000 pounds in top-rope falls when there was slack in the system or the wall was so steep the climber swung out when he fell. Because the failure of a top-rope anchor would likely lead to a serious or fatal accident, make sure top-rope anchors are as strong as those you would set for a belay.
Here's one article mentioning the testing of toprope falls generating forces in excess of 1000lbs.
My recollection was that in at least one set of tests (not necessarily this articles' tests), forces up to 1800 were generated. As a result, that's why I never use the smaller screw gates on my anchor set ups (1760lbs).
edit - subject title for clarity only talking screw gate quick links. Not carabiners.
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Are you talking about quick links or screw links, munge? 5/8" or smaller?
What do you prefer to use?
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At 1760# per 5/16" quicklink times two( two bolt anchor) =...........calculating........calculating.......3520#'s total load strength evenly shared between the two bolts.
Depending on the intended use of rigging hardware (such as for lifting people as opposed to lifting "stuff") the rated strength marked on the item is actually up to 50% or more of the tested failure strength. Ask the Dan Merrick Laboratories to break some, he has the rig for it. Or I bet he has already.
Why would you toprope from quicklinks when you can simply clip the hangers with draws? The quicklinks are for rapping only.
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Pretty sure we are talking about mini locking carabiners right munge?
1,800lbs in a TR fall? Man, that would be hard in the real world me thinks.
Like a monster loop of slack, and a overhanging fall?
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O man, and I liked my small screw gate carabiners.
Isn't it the more slack, the less the impact unless there's so much slack there's impact.
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At 1760# per 5/16" quicklink times two( two bolt anchor) =...........calculating........calculating.......3520#'s total load strength evenly shared between the two bolts.
Depending on the intended use of rigging hardware (such as for lifting people as opposed to lifting "stuff") the rated strength marked on the item is actually up to 50% or more of the tested failure strength. Ask the Dan Merrick Laboratories to break some, he has the rig for it. Or I bet he has already.
Why would you toprope from quicklinks when you can simply clip the hangers with draws? The quicklinks are for rapping only.
1. Assumes even spread of weight distribution, generally.
2. Rated strength whether over built or not can be subject to manufacturing flaws.
3. You wouldn't toprope through them regularly. Sessions you use your own gear. But why put in something you can't let the last person top rope through? e.g. I lead Mrs. Munge up, I don't want her to clear gear and loop back in, so I lower her often times. It would be nice to be able let her TR that one time through the anchor set up so that I don't have to relead. *** This in no way suggests that Mrs. Munge weighs 1760lbs. ***
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What's wrong with small screwlocks? The article doesn't mention them. I have a bunch of Trango SuperFly Screwlocks, like them and use them often. They about have the same load rating as carabiners generally do.
Strength - Gate Closed: 24 kN (Major), 7 kN (Minor)
Strength - Gate Open: 9 kN
24 kn is 5395 lb
I guess we are talking about quicklinks. The Chinese ones suck.
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Pretty sure we are talking about mini locking carabiners right munge?
1,800lbs in a TR fall? Man, that would be hard in the real world me thinks.
Like a monster loop of slack, and a overhanging fall?
I don't know what length of slack it would take, but a big guy like me flailing around, and a stoner belayer? Happens all the time.
Not 'mini locking biners'.
Talking about oval shaped screw gate quick links.
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What's wrong with small screwlocks? The article doesn't mention them. I have a bunch of Trango SuperFly Screwlocks, like them and use them often. They about have the same load rating as carabiners generally do.
Strength - Gate Closed: 24 kN (Major), 7 kN (Minor)
Strength - Gate Open: 9 kN
24 kn is 5395 lb
I guess we are talking about quicklinks. The Chinese ones suck.
screw gate quick links. NOT Trango.
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I bought some 5/16" stainless quicklinks on Ebay once and tested a few. The threads didn't engage on one end and they pulled open at something like 1500lbs. I sent them back the the seller and he relisted them as 1500 lb capacity. I suppose somebody bought them.
Here's a photo of some tested quick links. The made in Thailand 5/16" failed at 14,600 lbs. The unmarked SS 5/16" is probably the same batch held 15,700 lbs and didn't fail although my test rig did. The 1/4" carbon steel went at 4950 lb.
Anyway, quicklinks are fine if you buy good ones. It is hard to tell good ones without testing. They are not well or accurately marked. If there are marks they are not consistent as to whether they indicate working or failure load.
Pretty hard to check capacity if you didn't buy or test them. That's why I never clip them for anything but rappels.
If you need to test something, I can do up to 20,000 lbs in the garage if you come by and help.
(http://danielmerrick.com/SOYO_photos/Quick_Link_Tests.jpg)
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Here's a SS 5/16" Marked safe working load (SWL) 1940 which I assume is lbs. It broke at 5810 lb.
5810/1940 = 3.0 safety factor
(http://danielmerrick.com/SOYO_photos/Quick_Link.jpg)
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I bought some 5/16" stainless quicklinks on Ebay once and tested a few. The threads didn't engage on one end and they pulled open at something like 1500lbs.
Anyway, quicklinks are fine if you buy good ones. It is hard to tell good ones without testing.
Yikes! the SS ebays failed at lower rated load than the carbon ones I see around various places?!
Exactly my point. You can't know in advance which are good and which are bad, unless you batch test the ones that are purchased over the counter. So on the whole, we should force everyone to go up a notch from the cheapo 1760lbs ones.
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Hahahaha. This is too good... Way to cover your rear.
*** This in no way suggests that Mrs. Munge weighs 1760lbs. ***
Hahaha, ahaha, haha.
I obviously got a kick out of that. Simple minds easily amused and all that I guess.
Just say no to links. Use ring hangers or rapp hangers. I've started to migrate away from links entirely, although I may have some in place on previous routes done in the area.
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O yah, by the way that did give a good giggle alright
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;D
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I was looking at the ratings for smash-links...only 700# for the most common type. Yikes!
These are "smashed" together for a cheapo rap anchor. Very common anchor.
These (pre-smash):
(http://www.southernyosemiteclimbing.com/SMF/photo_album_resized/smashlink_resized.jpg)
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I need to test some smash links. Always been curious about them. Used to be part of the standard issue rap anchor.
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I was looking at the ratings for smash-links...only 700# for the most common type. Yikes!
These are "smashed" together for a cheapo rap anchor. Very common anchor.
These (pre-smash):
(http://www.southernyosemiteclimbing.com/SMF/photo_album_resized/smashlink_resized.jpg)
Despise these. Hard to replace if damaged, and they always rust.
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I have trouble believing they have a 700 lb limit so I hope you test some in the laboratory, Dan.
I noticed our camp chairs only have a 200lb weight limit. Doesn't that seem unreasonable for a chair sold in well-fed Merica?
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You can't forget that the angle between anchors plays a big part in load generated.
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https://youtu.be/Ly8dIIH7a9Y (https://youtu.be/Ly8dIIH7a9Y)
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Cool Dan. Pretty stinkin strong! I have never seen a cold shut that was closed in an anchor just open. Like at Owens RG.
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Enjoyed the mesmerizing video!
Didn't see your results posted until just now below your video:
"The labels say the working load limits are:
5/16" smash link 700 lbs
3/8" smash link 1250 lbs
5/16" cold shut 1300 lbs
3/8" cold shut 1900 lbs
Based on my tests of one piece, the factors of safety are:
5/16" smash link 3.9
3/8" smash link 4.1
5/16" cold shut 2.4
3/8" cold shut 2.5
The load display in the video is kilopounds or kips."
What were you learning from the vice? Did you test just the ones shown or more? The Dan labs look like fun!
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You can't forget that the angle between anchors plays a big part in load generated.
(http://www.southernyosemiteclimbing.com/SMF/photo_album_resized/loads_resized.jpg)
Quick web search result yielded this photo.
Ironbasher, your name fits in well here. :)
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Enjoyed the mesmerizing video!
Didn't see your results posted until just now below your video:
"The labels say the working load limits are:
5/16" smash link 700 lbs
3/8" smash link 1250 lbs
5/16" cold shut 1300 lbs
3/8" cold shut 1900 lbs
Based on my tests of one piece, the factors of safety are:
5/16" smash link 3.9
3/8" smash link 4.1
5/16" cold shut 2.4
3/8" cold shut 2.5
The load display in the video is kilopounds or kips."
What were you learning from the vice? Did you test just the ones shown or more? The Dan labs look like fun!
what's a factor of safety?
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Fall factor?
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I have never seen a cold shut that was closed in an anchor just open.
Neither have I but this test was how they are intended to be used. I did this because I thought they might be stronger than a smash link which it seems is true. It would be better to use a cold shut in an anchor than a smash link. Quick links are of course even better.
what's a factor of safety?
A good thing. The factor of safety in this case is just the ratio between the breaking strength and the safe load. It is interesting that the FS seems to be different for the two types. I would have expected them to be the same since they have the same purpose. Factors of safety vary for different materials, load types, etc. Most buildings use a FS of about 2. lifting equipment in an industrial setting would probably have a FS of 2 or 3, lifting above people 4. If you are lifting people, I believe OSHA requires a FS of 7. FS is higher if there are lives at risk, if the failure type is brittle and if there is no redundancy. This paragraph takes the traditional Allowable Stress Design (ASD) approach. Up until the last 10 years or so, metal and wood structures were designed this way.
There is another way to provide for some safety which was for many years called ultimate load method or strength design (SD). In this approach the minimum breaking load is calculated then a factor is applied to increase the design load. Different loads have different factors. If a load is very predictable, the load factor is small. SD design has been used for concrete structures since the mid 1960's.
The version currently in favor is called Load and Resistance Factor Design or LRFD. The loads are factored up by various amounts based on their predictability and the strength or resistance is factored down based on predictability and brittleness. LRFD is becoming common for steel structures and is used for wood structures.
The three design concepts above will give the same size structure (beam, column, whatever) within about 10%. Steel designers like the 10% savings because it saves money. LRFD is more work and book keeping.
Climbing gear is rated according to an approach that is not ASD but has some aspects similar to SD and LRFD. For climbing gear the capacity or strength given (e.g. a 22 kN carabiner) is the minimum breaking strength so there really is no factor of safety incorporated in the strength. The load is unclear. For lead climbing the load is something like 2000 to 3000 lbs on the rope. Not because a falling climber can't generate larger forces but because it is assumed he will be dead if he does. Somplace around 10 G impact and your insides get scrambled. So, if the climber is to survive a 3000 lb force on the rope, the carabiner and anchor have to resist pretty much twice that. Small carabiners are rated at 22 Kn which is 5000 lbs
As far as I can tell, UIAA doesn't have seperate capacities for rappel gear. I think they feel it should be the same as lead gear. It is possible to shock load the rope on rappel but I personally think it is is acceptable to have rappel gear with a lower capacity than lead gear.
If a smash link is used to provide rappel capability at an anchor, The OSHA FS of 7 might be a reasonable place to start. A big climber with bear might weigh 300 lbs. 300x7=2100 lbs. I would hesitate to suggest using anything for rappel with less capacity than this. On the other hand, I have no doubt that I have used anchors with less capacity than that for rappel.
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It is possible to shock load the rope on rappel but I personally think it is is acceptable to have rappel gear with a lower capacity than lead gear.
If a smash link is used to provide rappel capability at an anchor, The OSHA FS of 7 might be a reasonable place to start. A big climber with bear might weigh 300 lbs. 300x7=2100 lbs. I would hesitate to suggest using anything for rappel with less capacity than this. On the other hand, I have no doubt that I have used anchors with less capacity than that for rappel.
Agreed, and while we can use differing less strong gear, for the uninitiated a clear standard clearly communicated proves better for the general public.
I found snap links in New Mexico used for lowering thru in a quarter inch diameter. It held one, why not more? Well because eventually the need for maintenance kicks in and lots of shit gear has no factor of safety.
Cold shuts for rap only would be hard to undo yes?
Unlike Clint, I don't carry tools for replacement, usually just a wrench. Wrench 🔧
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By the way, that's a typo. "big climber with bear" should be "big climber with beer"