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adatesman
Apr 23, 2008, 6:32 PM
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reg
Apr 23, 2008, 6:50 PM
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not all that familar with quick links. memory tells me they're larger at the thhd's. the 7 mm (apx 1/4") link has a 5/16 thhd dia.. is that about right? anyway - 15 to 22 ft-lbs sounds right. we would want the right coefficient of friction on the thhd's to keep um tight!
u must be bored today 
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adatesman
Apr 23, 2008, 6:59 PM
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jt512
Apr 23, 2008, 7:10 PM
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adatesman wrote: Yup, the diameter of the body of the quicklink is 7mm and the threads are considerably larger (M10x1.25). I always figured that 15 - 22 ft-lb was where its at, but having just realized the documentation that comes with Petzl's links says something completely different I'm a bit perplexed what the correct value to use is. It could be a misprint, but that's also what's listed in the PDF on their site. -aric.
I wonder if Petzl might have printed the wrong units, or equivalently, misplaced the decimal points. If the figures in the table are actually daN-m, then 2.5 daN-m = 18.4 ft-lb, which is in the expected range. Maybe you should email Petzl.
Jay
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tradklime
Apr 23, 2008, 7:14 PM
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Perhaps, we should look at it differently. What would be a reaosonable torque to represent what is done in the field. In my mind, part of the benefit of tighening the links to a specified torque (for the purpose of testing) is consistency. I would guess that finger tightening could result in more variable tightening than wrenching to a specified torque.
When you snug them down to what seems appropriate, what kind of torque are you applying?
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reg
Apr 23, 2008, 7:21 PM
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1.85 ft-lbs? i can get that with my fingers on a good day (i think) - a couple flats past finger tight is what your lookin for. if i was leaving them behind on a rap - finger tight would be fine with me. even if they vibrated open, i think there good for ah bit more then 3kn (open). but leaving em some where for others to use - well, i'd want to see ah dozen or so ft-lb's on um.
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tradklime
Apr 23, 2008, 7:24 PM
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Aric,
Take a look at this site : http://www.directindustry.com/...link-7993-53159.html
Under "specs." in the upper left side there is a link to torque requirements as follows:
Tightening torque (N,m)
Ø F Couple
2,5 0,15
3,0 0,30
3,5 0,60
4,0 0,70
5,0 0,80
6,0 1,20
7,0 2,50
8,0 3,00
9,0 4,50
10,0 7,00
12,0 9,00
14,0 12,00
16,0 18,00
18,0 30,00
20,0 40,00
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krusher4
Apr 23, 2008, 7:59 PM
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Please don't leave these when you bail off a sport route mid-route. They have to be removed before the bolt can be clipped i.e. many times enroute one handed, when they've rusted shut.....this is what 'bail' biners are for.
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jt512
Apr 23, 2008, 8:00 PM
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krusher4 wrote: Please don't leave these when you bail off a sport route mid-route. They have to be removed before the bolt can be clipped i.e. many times enroute one handed, when they've rusted shut.....this is what 'bail' biners are for.
That would be a good point in the right thread.
Jay
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adatesman
Apr 23, 2008, 9:37 PM
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james481
Apr 25, 2008, 7:05 AM
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I understand that you're seeking these figures primarily for testing purposes, but we should keep in mind that the torque specs Petzl gives are probably for getting maximum strength from the link, which (at least with a well rated link like a Petzl) is probably not the primary consideration when using one in the wild.
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adatesman
Apr 25, 2008, 1:33 PM
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james481
Apr 25, 2008, 5:36 PM
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adatesman wrote: Hey James481, True, I'm looking for it for testing purposes
Speaking of, in my first post I forgot to thank you for the informative and entertaining testing, so, you know, thanks. 
adatesman wrote: but the bigger issue arising out of it is that it appears that conventional wisdom regarding use of their links is wrong per the manufacturer's installation instructions. If that's the case, trying to correct this may be a good idea, especially if it turns out that severe overtightening (as would be the case with finger tight + 1/4 turn if the correct spec is 2.5Nm) reduces the strength considerably.
Well, I suppose the intended usage of the links and what exactly constitutes "considerably" determines the seriousness of this potential issue. I somewhat doubt that the links are weakened what I would call considerably with any reasonable amount of torque on the threads.
adatesman wrote: As for how they're used in the field, in permanent installations its just as easy to put a dab of releasable locktite on it as it is to overtighten them, so why install them in a manner contrary to the manufacturer instructions?
Particularly in a climbing application such as a rap anchor, I would be more inclined to trust a well-torqued link with a lower absolute strength than one that's held closed by something like Loctite. I may be incorrect, by my notion is that Loctite on a very loosely torqued link won't hold up to constant weathering and cyclical loading very well. Of course, you should visually and manually inspect any link (or anything else) before trusting your life to it, but I don't generally make a habit of carrying Loctite on my rack if I were to encounter one that had loosened up.
adatesman wrote: I'd be curious to do more testing on them to include finger tight + 1/4 turn and really wrenching down on them, but at $5 a pop I'm not so inclined to do it unless a bunch of people each donate one for the tests to spread out the costs.
I'd be interested to see this as well, but they are pretty expensive hardware to be breaking very many of them. Personally, I only own one of them, which I use to secure my Rescuecender to my belay loop for solo top rope. If it ever wears out or I find something better, you'll have first dibs on it.
adatesman wrote: For what its worth the non-Petzl quicklinks Tradklime sent me all failed by the threads shearing off the body of the quicklink (at only finger tight), so I suspect that when I get a chance to test the additional ones he sent that are finger tight + 1/4 turn that they'll fail at a much lower load. And given that they were arguably marginal in the first place, a lower failure load due to overtightening isn't a good thing. While the threads on the Petzl links weren't the source of their failure, there are non-Petzl links in use out in the field (as in Mojomonkey's gym, for instance) so this might be a somewhat major issue that's so far gone unnoticed and is in need of attention. -aric.
Although I'm very interested to see the results of any tests you might end up doing, I again have to voice my skepticism that this could be qualified as potentially a "somewhat major issue", due to my assumption that the torque probably doesn't affect the strength to any great degree along with the lack of reported field failures of even the cheapest Chinese links, given the numbers of them out there in use every day.
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Roasta
Apr 25, 2008, 11:16 PM
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For what it is worth; in my old trade several items I worked with were secured at 25in lbs. This roughly equated to a little more than finger tight - give or take the 'gorillas' hand/finger strength.
Even with the Torque wrench this figure could easily be achieved prior to the thread being at it's correct bottom out point if it was slightly dirty, poor thread condition, weight and incorrect alignment of item etc. This highlights the need to know the bolt/nut/collar is correctly bottomed out rather than relying on a figure that is now useless.
When trying the 'calibrated elbow' method of hand tightening, using some sort of non indicative wrench; where you grasp the wrench etc makes a massive difference due to leverage. Also, assuming you are using a 'crows foot' attachment on your torque wrench; ensuring it is at 90degs to the head avoids our length extension and therefore leverage issues which will contribute to over tightening (as I am sure a lot here are all well aware).
To me if the collar is run down to where the threads are bottomed out, (and no further to cause thread damage), then this engagement of the threads is what will maintain the links 'loop continuity'. Sufficient (IMHO)- depending on it's intended environment of use and ability to monitor.
To torque accurately, as you have stated, serves to avoid thread damage and stress. The other thing it seems to achieve is a viable safe 'minimal/maximal' (ideal) working torque or load to help reduce the likely-hood of the nut/bolt/collar vibrating loose or being knocked loose.
In the real life climbing world - they are probably going to be hand tightened for a 'bail' type scenario. In this case I would be aiming to make sure the threads are completely engaged / bottomed out and firm enough to avoid the loosening issue.
If they are used in a permanent fixture type environment and the applicable tooling is available (and calibrated), then following the specs makes sense.
I would be happier to use one that had been loosely but completely tightened and engaged and then coated with a torque sealer or super-glue or alike to allow you to inspect it's integrity rather than hoping some dude didn't wrench on the thing with a pair of crappy vice grips and an extension bar.
If we have a spanner/shifter but no indicative torque wrench - 'choke' the spanner/shifter close to the head to avoid leverage and over tightening issues and run the collar down to bottom out point and tighten to a firm but not to tight position..... The question is what is my version of that as opposed to someone else?? Well I guess unless you have tightened a million items (quick links) with a valid torque wrench to the manufactures specs to develop some sort of feel and experience for that amount (kind of what Reg mention about using the flats of the collar as a guide) - you can only guess what the variations will be. Hence why manufactures specify specific torques.
It would be interesting if they have a + or - allowance to their torque figures for the case in question in this thread...
I guess we don't torque our screw-gates closed; firm but not too tight concept.
Anyway I understand you need the figures to be accurate for valid test results and comparisons.
To relate to our real world environment maybe the figures aren't really that helpful - only to give us a baseline to develop that feel we spoke of.
Coming up with a standard of say:
- Run the collar down until safely and completely engaged and tightening a further 2 flats (Like Reg suggested - or whatever actually roughly equates to the specs) maybe a more valid 'real world' use in a climber case.
If the links are used in an environment where the implementer of the said links maybe sued for incorrect installation - then definitely use a calibrated torque wrench and follow the manufactures specs to cover thy ass.
Just my view here - sorry if I am off track a little.
Keep up the generous work Aric.
(This post was edited by Roasta on Apr 26, 2008, 2:43 AM)
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jt512
Apr 25, 2008, 11:23 PM
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Roasta wrote: For what it is worth; in my old trade several items I worked with were secured at 25in lbs. This roughly equated to a little more than finger tight - give or take the 'gorillas' hand/finger strength. [..] If they are used in a permanent fixture type environment and the applicable tooling is available (and calibrated), then following the specs makes sense.
As a practical matter, at many crags, if the link is going to be used in a permanent anchor, it needs to be tightened enough so that it can't be unscrewed by hand and stolen, as well. Maybe that means that larger links, with higher torque specs should be used.
Jay
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Roasta
Apr 25, 2008, 11:26 PM
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Beat me too it Jay.
I just edited to add a comment about checking the integrity which may also contribute to stopping the issue you mentioned.
..
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andrewbanandrew
Apr 28, 2008, 10:46 AM
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not that this has anything to do with anything but you can improvise a wrench out of one quicklink to use on another
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acorneau
May 1, 2008, 8:07 PM
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Howdy folks,
Just thought I'd toss this in:
I found that CAMP is making CE-certified quicklinks; ovals and deltas in 8mm and 10mm. Unfortunately, no WWL or MBS ratings listed.
http://www.camp-usa.com/...l-quick-link-934.asp
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curt
May 2, 2008, 4:48 AM
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More importantly, how many angels can dance on the head of a pin, anyway?
Curt
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adatesman
May 2, 2008, 2:20 PM
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curt
May 2, 2008, 3:22 PM
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adatesman wrote: curt wrote: More importantly, how many angels can dance on the head of a pin, anyway? Curt I think you have the wrong forum, Curt. But since you asked, only four angels can dance on the head of a pin. There didn't used to be a limit, but OSHA passed the Angel Safety Law a few years back which limits the number and requires that the pin be inspected twice each year for structural defects.
My question is nonsensical, of course--as is the entire premise of your thread here. As I have stated before, tightening a quick-link 1/4 turn beyond finger tight (versus finger-tight only) will have absolutely no effect on the strength of the link.
Curt
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AlexCV
May 2, 2008, 4:05 PM
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acorneau wrote: I found that CAMP is making CE-certified quicklinks; ovals and deltas in 8mm and 10mm. Unfortunately, no WWL or MBS ratings listed.
From a table on the italian website (http://www.camp.it/....aspx?codicemenu=355) it seems that the quicklinks are at least 40 kN for zinc plated and 10kN more with slightly lighter weights for the stainless steel ones (the table seems to have ratings and gate opening reversed).
(This post was edited by AlexCV on May 2, 2008, 4:07 PM)
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adatesman
May 2, 2008, 6:07 PM
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curt
May 3, 2008, 2:31 AM
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adatesman wrote: Hi Curt, I have to disagree on the premise of this thread being nonsensical. From Petzl's response its quite clear that the conventional wisdom of going a quarter turn past finger tight is incorrect for their quicklinks, which leaves us with the question of how much will this overtightening effect the ultimate strength of the quicklinks. If you have any data or analysis to justify your opinion that it doesn't make a difference I'd love to see it. Engineering-wise, tightening the nut on the quicklink will load the threads in shear, so obviously this preload will reduce the ultimate strength of that part of the quicklink...
No, that is false. No linear relationship exists between the "pre-loading" you are citing and the ultimate failure limit of the quicklink. In other words, tightening the quicklink beyond finger tight will have no effect on its ultimate strength until you tighten the link so far that you structurally damage or weaken the metal in the thread area. My guess (although I have no proof) is that you need far more than 1/4 turn beyond finger tight to get to that point. I am certainly willing to bet that testing will bear my opinion out.
Curt
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