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During the recent Glencoe jamboree I was reminded that about a year ago there were some threads about dropping krabs and other bits of aluminium kit down crags discussing whether it was OK to re-use them. I said I would write a note on the subject, I did and sent it in with some photos provided by MikeC.
As Mick has been too busy with other things it has not be published yet so I have put it here:
http://bullroar.vox.com
As Mick has been too busy with other things it has not be published yet so I have put it here:
http://bullroar.vox.com
In reply to Horse: What's your background in this field Horse? This is what I've been telling one of my friends for years and he's going to argue with me when I send him a link to your article!
In reply to Horse: From what i can glean the best advice is just bin it ... after all £5 for a new crab is a tiny price to pay in comparison to catastrophic failure in use.
ps. retired crabs make natty earings, knuckledusters (for those in South Shields) and keep the kids amused for hours!!
ps. retired crabs make natty earings, knuckledusters (for those in South Shields) and keep the kids amused for hours!!
In reply to muppetfilter:
The pertinent bit is at the end "...make an informed choice.." and that choice is yours but dropping a krab is not a disaster. If you replace a krab or belay device everytime you drop it those £5 are soon going to mount up.
The pertinent bit is at the end "...make an informed choice.." and that choice is yours but dropping a krab is not a disaster. If you replace a krab or belay device everytime you drop it those £5 are soon going to mount up.
In reply to Horse: So will a few months in traction, even as a yorkshire man i value my health above mere money.buy new gear.
did you drop gear in a controlled replicatable manner and destruction test it or submit it to MPI,UT or x-ray ? If you didnt follow a repeatable series of tests and claims are not surely valid??
did you drop gear in a controlled replicatable manner and destruction test it or submit it to MPI,UT or x-ray ? If you didnt follow a repeatable series of tests and claims are not surely valid??
In reply to muppetfilter:
I haven't tested anything although the likes of BD have tested old/used krabs. What I was doing was explaining why minor damage to the surface of hot forged aluminium krabs is not a cause for concern because of the fundamental material property of toughness.
I am not sure what the testing would tell me other than the surface of an item tested might contain surface breaking flaws, of itself unsurprising.
Like I say your choice. I have never replaced a krab because of I have dropped it and I have dropped and fallen on plenty.
I haven't tested anything although the likes of BD have tested old/used krabs. What I was doing was explaining why minor damage to the surface of hot forged aluminium krabs is not a cause for concern because of the fundamental material property of toughness.
I am not sure what the testing would tell me other than the surface of an item tested might contain surface breaking flaws, of itself unsurprising.
Like I say your choice. I have never replaced a krab because of I have dropped it and I have dropped and fallen on plenty.
In reply to Horse: light surface scratches are not an indication of sub-surface fractures. All i would suggest is it is a bold statement to say dropping a crab is not going to weaken/damage it. I bow to your obvious professional knowledge but it is shakey ground to suggest an impact will not affect a crab.The real crux is to identify what will and will not compromise the safety of a crab. They are tough little buggers, i have had to de-comission a number a few years ago and it takes some welly with a 12lb hammer... ;0)
In reply to muppetfilter: Do you often get sub-surface fractures in materials with relatively high fracture toughness?
I know fatigue cracks usually propogate from the surface, but not surea bout these "sub-surface" fractures? Have you got any good references......it's always good to learn more!
I know fatigue cracks usually propogate from the surface, but not surea bout these "sub-surface" fractures? Have you got any good references......it's always good to learn more!
In reply to muppetfilter:
Have you got that new nut key yet??? 8-0
> (In reply to Horse) So will a few months in traction, even as a yorkshire man i value my health above mere money.buy new gear.
>
>
Have you got that new nut key yet??? 8-0
In reply to Horse:
I've got a norweigan mate (good credentials) who has always recommeded binning them after being dropped. I'm quick to recommend mine being replaced if SOMEONE ELSE drops it 8-)
Personally i just use my own judgement... after all it's my life...
like i'll use biners that have been knocked about a bit...
i'll abseil off one good anchor...
i'll climb without a helmut most times...
and if i fancy eatin an out-of-date yoghurt, well i'll jolly-well eat it!
NB:Cragrat rich reserves the right to refusal of any persons offering the use of their climbing gear and maintains a strict policy of persons bringing their own gear to use when climbing in partnership with him. Climbing is a dangerous activity and should only be undertaken by individuals of sufficient mental capacity for risk taking. Those suffering from psychological disorders which affect their ability to be responsible for themselves or others should take up snowboarding
I've got a norweigan mate (good credentials) who has always recommeded binning them after being dropped. I'm quick to recommend mine being replaced if SOMEONE ELSE drops it 8-)
Personally i just use my own judgement... after all it's my life...
like i'll use biners that have been knocked about a bit...
i'll abseil off one good anchor...
i'll climb without a helmut most times...
and if i fancy eatin an out-of-date yoghurt, well i'll jolly-well eat it!
NB:Cragrat rich reserves the right to refusal of any persons offering the use of their climbing gear and maintains a strict policy of persons bringing their own gear to use when climbing in partnership with him. Climbing is a dangerous activity and should only be undertaken by individuals of sufficient mental capacity for risk taking. Those suffering from psychological disorders which affect their ability to be responsible for themselves or others should take up snowboarding
In reply to Alasdair Fulton: I couldnt find info on the alloys used in crabs but the (i have been reliably informed) charpy bar test can be used to determin the likelihood of a material to fracture under impact, Its main industrial uses are quality monitoring and material selection.The other methods of testing are a bit impracticle, my mum gets a bit annoyed when i bring radioactive sources home for a bit of bombing!! :0(
ps. rich, nutkeys aren,t as worrying as overcammed friends!!! Thats a whole different area of physics you might want to look up. ;0)
ps. rich, nutkeys aren,t as worrying as overcammed friends!!! Thats a whole different area of physics you might want to look up. ;0)
In reply to muppetfilter: Yeah, I know ho wfracture toughness is tested, I was just quite interested in these sub surface cracks.
In reply to Horse:
Hi Horse you might remember me. I was the one who made the thread last winter after dropping my belay device (BD ATC Guide) from over 100m. See
http://www.ukclimbing.com/forums/t.php?t=234809&v=1#x3452919
I replaced my ATC at the end. Although I did inspected it and think it's alright, I wouldn't be so happy to recall even the tiniest hidden doubt when I'm literally hanging two lives on it.
A few weeks ago I went climbing at my local limestone (15m high) and found a rather worrisome object... half of a broken karb. How it was broken is a mystery - perhaps jammed in a crack while someone fell on it. Couldn't imagine these things do break until I saw one.
Hi Horse you might remember me. I was the one who made the thread last winter after dropping my belay device (BD ATC Guide) from over 100m. See
http://www.ukclimbing.com/forums/t.php?t=234809&v=1#x3452919
I replaced my ATC at the end. Although I did inspected it and think it's alright, I wouldn't be so happy to recall even the tiniest hidden doubt when I'm literally hanging two lives on it.
A few weeks ago I went climbing at my local limestone (15m high) and found a rather worrisome object... half of a broken karb. How it was broken is a mystery - perhaps jammed in a crack while someone fell on it. Couldn't imagine these things do break until I saw one.
In reply to muppetfilter:
I think Black Diamond did a lot of controlled destruction tests like this and results shown no weakening with dropped gear.
We can't possibly destruction test any gear we're using (new or old) so we can only trust the current engineering theory and experience.
> did you drop gear in a controlled replicatable manner and destruction test it or submit it to MPI,UT or x-ray ? If you didnt follow a repeatable series of tests and claims are not surely valid??
I think Black Diamond did a lot of controlled destruction tests like this and results shown no weakening with dropped gear.
We can't possibly destruction test any gear we're using (new or old) so we can only trust the current engineering theory and experience.
In reply to Alasdair Fulton: they are fractures under the surface.. ;0) ones you cant see that could be caused by an impact.£4 is such a small amount of money to quibble over.
google "impact fracture metal" hours of fun and probably a Phd.
And mum really does get upset when i have the rad-haz tape in the conservatory...
google "impact fracture metal" hours of fun and probably a Phd.
And mum really does get upset when i have the rad-haz tape in the conservatory...
In reply to jamestheyip: I have seen 30 year old kong crabs sent away for testing and fail at 30kn!!!
There are so many factors involved it is impossible to say "dropped crabs are ok" If im on the fourth pitch of a route i rally dont want to lean back and think that crab i dropped 100ft will probably be ok.
dropped hasn't been quantified 10mm or 100m?
There are so many factors involved it is impossible to say "dropped crabs are ok" If im on the fourth pitch of a route i rally dont want to lean back and think that crab i dropped 100ft will probably be ok.
dropped hasn't been quantified 10mm or 100m?
In reply to muppetfilter:
Of course you can argue this and that in search of certainty but that is not what it is about. Experience shows that krabs don't fail in a brittle manner, see BD, others tests and a lack of reports fo krabs spontaneously cracking. What I have done is offer an explanation for this observation. And I have not said dropping a krab will have no effect what I said was minor scratches from dropping are not a cause for concern with regard to crack propagation in a brittle manner and gave some guidance on how to assess the damage. I am comfortable with that, I find it neither "bold" nor "shakey".
As to sub surface defects, how do you know they are not there before it was dropped? You don't. In fact there are millions of them between the individual grains in the alloy much like there are millions of cracks in every concrete bridge you drive over. The method of krab production, hot forging, produces a very good microstucture that is less prone to inherent defects where sub surface defect would initiate than other methods of production. In fracture terms surface breaking defects are worse than buried ones, things get concentrated at one rather than both ends of a crack. Taking these factors into account for any subsurface defect to be a problem it is going to have to be very much larger than the surface defect to cause failure.
Of course you can argue this and that in search of certainty but that is not what it is about. Experience shows that krabs don't fail in a brittle manner, see BD, others tests and a lack of reports fo krabs spontaneously cracking. What I have done is offer an explanation for this observation. And I have not said dropping a krab will have no effect what I said was minor scratches from dropping are not a cause for concern with regard to crack propagation in a brittle manner and gave some guidance on how to assess the damage. I am comfortable with that, I find it neither "bold" nor "shakey".
As to sub surface defects, how do you know they are not there before it was dropped? You don't. In fact there are millions of them between the individual grains in the alloy much like there are millions of cracks in every concrete bridge you drive over. The method of krab production, hot forging, produces a very good microstucture that is less prone to inherent defects where sub surface defect would initiate than other methods of production. In fracture terms surface breaking defects are worse than buried ones, things get concentrated at one rather than both ends of a crack. Taking these factors into account for any subsurface defect to be a problem it is going to have to be very much larger than the surface defect to cause failure.
In reply to muppetfilter:
Charpy testing is not a direct measure of toughness it is a measure of the energy absorbed by a specimen in a standard impact test at a given temperature. Of itself it cannot be used to predict crack stability or propagation. For some materials there is a correlation with actual toughness (measured in a Crack Tip Opening Displacement (CTOD)test)and Charpy tests are particularly good for estimating the transition temperature from ductile to brittle behaviour in materials (for example steel) that show such a transition.
I am not sure what use bombing (X-ray) would be in estimating toughness, it might tell you there was a defect and give some estimate of size of said defect. It won't tell you if said defect will propagate under load.
To jamestheyip, indeed that was one of the threads I had in mind. Your call and you have to make the one you are happy with.
Charpy testing is not a direct measure of toughness it is a measure of the energy absorbed by a specimen in a standard impact test at a given temperature. Of itself it cannot be used to predict crack stability or propagation. For some materials there is a correlation with actual toughness (measured in a Crack Tip Opening Displacement (CTOD)test)and Charpy tests are particularly good for estimating the transition temperature from ductile to brittle behaviour in materials (for example steel) that show such a transition.
I am not sure what use bombing (X-ray) would be in estimating toughness, it might tell you there was a defect and give some estimate of size of said defect. It won't tell you if said defect will propagate under load.
To jamestheyip, indeed that was one of the threads I had in mind. Your call and you have to make the one you are happy with.
In reply to muppetfilter:
Ok.... here goes, {lights dim} [drum roll sounds].... wait for it... "dropped crabs are ok" da da! [bows] 8-)
> (In reply to jamestheyip)
> There are so many factors involved it is impossible to say "dropped crabs are ok"
> There are so many factors involved it is impossible to say "dropped crabs are ok"
Ok.... here goes, {lights dim} [drum roll sounds].... wait for it... "dropped crabs are ok" da da! [bows] 8-)
In reply to Cragrat Rich: totally agree , wonderful, like dennis leary as edgar in that demolition man speech
In reply to Horse: Of course they're ok, they probably see more abuse swinging around on your harness or bashed about in your pack.
Think of other bits of gear climbers clip themselves to such as a piton, after smashing it into a crack with a hammer!
Think of other bits of gear climbers clip themselves to such as a piton, after smashing it into a crack with a hammer!
In reply to Horse: Could you please have a word with the chaps at DMM I spoke to at the NEC as they seem to be under the Impression that dropped crabs should be retired. Obviously they only make inovative world class crabs. What would they know? Maybe its an evil plot to sell more crabs?
In reply to muppetfilter:
Is there not an obvious reason for this? There is an element of doubt and and element of the nature of the fall, so for legal and professional reasons they can't blanket say dropped krabs are ok. It is safer for them to say to retire and replace. Have you never read a leaflet in that comes with gear? They are ludicrously conservative with their advice - for example tiny micros are 'for aid use only'. Loads of us have them and use them for pro.
> (In reply to Horse) Could you please have a word with the chaps at DMM I spoke to at the NEC as...
Is there not an obvious reason for this? There is an element of doubt and and element of the nature of the fall, so for legal and professional reasons they can't blanket say dropped krabs are ok. It is safer for them to say to retire and replace. Have you never read a leaflet in that comes with gear? They are ludicrously conservative with their advice - for example tiny micros are 'for aid use only'. Loads of us have them and use them for pro.
In reply to muppetfilter:
Or called covering their a**es...
Out of interest - we know what GG (Horse) does, what do you do?
> (In reply to Horse) Could you please have a word with the chaps at DMM I spoke to at the NEC as they seem to be under the Impression that dropped crabs should be retired. Obviously they only make inovative world class crabs. What would they know? Maybe its an evil plot to sell more crabs?
Or called covering their a**es...
Out of interest - we know what GG (Horse) does, what do you do?
In reply to MJH:
filters muppets can't you read!
filters muppets can't you read!
In reply to Horse:
I am with Horse on this one, and recall reading stuff from the BD testers about this.
I am with Horse on this one, and recall reading stuff from the BD testers about this.
In reply to muppetfilter:
Or an individual (representing a respected company) offering the simplest safe advice to a person he does not know, who's judgement he has no reason to trust. Basically, a chap covering his ass.
If you want to bin dropped kit, fine.
The deepest surface defects in my krabs are bolt hanger nicks (which I occasionally file out), not impact damage from drops. Out of interest, would you bin a krab after a bit of redpoint abuse?
Horse: An interesting though (as has been proven above) probably futile effort at shedding some light on modern materials. Now what about that pesky metal fatigue if I'm prone to resting on my quickdraws...
jk
> Could you please have a word with the chaps at DMM I spoke to at the NEC as they seem to be under the Impression that dropped crabs should be retired. Obviously they only make inovative world class crabs. What would they know? Maybe its an evil plot to sell more crabs?
Or an individual (representing a respected company) offering the simplest safe advice to a person he does not know, who's judgement he has no reason to trust. Basically, a chap covering his ass.
If you want to bin dropped kit, fine.
The deepest surface defects in my krabs are bolt hanger nicks (which I occasionally file out), not impact damage from drops. Out of interest, would you bin a krab after a bit of redpoint abuse?
Horse: An interesting though (as has been proven above) probably futile effort at shedding some light on modern materials. Now what about that pesky metal fatigue if I'm prone to resting on my quickdraws...
jk
In reply to muppetfilter:
It rather depends on the question you ask and whether the person you have asked is worried about product liability. If I were in DMM's shoes I suspect I might be equally cautious.
I am not convinced you have understood what I have been saying. I have not said keep damaged karabiners, I thought I was quite clear about that. What I have said is that if there is no obvious sign of visible damage on a dropped modern krab then the concern the part will subsquently fail by brittle fracture (based on what might have happened to old steel krabs) intiating from a crack is unlikely. As I have also said the choice to keep or bin is yours not mine or dare I say DMM.
It rather depends on the question you ask and whether the person you have asked is worried about product liability. If I were in DMM's shoes I suspect I might be equally cautious.
I am not convinced you have understood what I have been saying. I have not said keep damaged karabiners, I thought I was quite clear about that. What I have said is that if there is no obvious sign of visible damage on a dropped modern krab then the concern the part will subsquently fail by brittle fracture (based on what might have happened to old steel krabs) intiating from a crack is unlikely. As I have also said the choice to keep or bin is yours not mine or dare I say DMM.
In reply to jkarran:
I'd be careful as I suspect you are thinning down the metal in a place where you might want some. You call.
> (In reply to muppetfilter)
>
> [...]
Out of interest, would you bin a krab after a bit of redpoint abuse?>
> [...]
>
Redpoint? That is what I use when editing reports I don't like on behalf of lawyers I'd be careful as I suspect you are thinning down the metal in a place where you might want some. You call.
In reply to Horse:
Agreed. Though you don't need to take much off at all (<<1mm) to remove the nicks and burrs. Basically it's just refinishing the surface which wouldn't be needed if I was fussy about having gear-end and rope-end krabs (which I'm not).
jk
> I'd be careful as I suspect you are thinning down the metal in a place where you might want some. You call.
Agreed. Though you don't need to take much off at all (<<1mm) to remove the nicks and burrs. Basically it's just refinishing the surface which wouldn't be needed if I was fussy about having gear-end and rope-end krabs (which I'm not).
jk
In reply to Horse: If anyone that doesn't agree with Horse drops some gear, just send it to me. I'll be sure it gets recycled properly
In reply to muppetfilter:
It may well be me who you spoke to at the NEC, although I don't in all honesty remember the conversation, as I did talk to a very large number of folk, so apologies for that. However having read this thread I'd like to emphasise a few points.
We as a company need to err on the side of caution when offering advise on subjects such as this where there are so many variables and differing circumstances. Very often it is impossible to offer a hard and fast explanation. If I was asked a direct question such as 'Would you retire a carabiner if it were dropped from a route' I would have to say retire it as I don't know the damage that may or may not have been caused in this particular case.
Various people make valid points, such as verify the shape against another biner of the same sort, check for obvious signs of distress, see if the gate mechanism is still working smoothly, etc etc. However nobody can be 100 % sure it will be ok. As I said before there are so many variables, how high, what did it land on , did anything land on the biner in the fall etc etc.
Yes, we do have to cover our arses as somebody so succinctly put it.
No it isn't a subtle plot to sell more biners.
Yes we do err on the side of caution with advice, and quite rightly so. We have 120 peoples livelyhood at stake her in North Wales, and wouldn't want to jeopardise this with a hefty lawsuite. But much MUCH More importantly we don't want to risk anybody getting hurt unneccessarily by offering ambiguous advice that could lead to confusion.
Our Instructions State in relation to Lifespan:
'It is very difficult to estimate this due to local use and storage conditions, but a conservative estimate would be ten years for metal parts................. however the following might reduce the lifespan to as little as one use: Fall Arrest/General wear/ chemical contamination/corrosion/gate malfunction/mechanical deformation/distortion/ heat contamination (over normal climatic conditions)'
Ultimately it is down to the individual to make a choice. In this case the consequences of the wrong choice could be catastrophic. That's not alarmist, that is merely stating that the consequences could be catastrophic. They might not be, but is it worth the risk.
Interestingly, and on a personal note, I have been climbing since the age of 12, and I am now entering my 50th year. I honestly can't remember dropping that many biners, certainly not enough to make me think that replacing them would be a major issue.(even if I had to pay for them all.)
As an aside, at the show we had a tensile tester to demonstrate the strengths of various biners. We had to abandon the demo on the second day as an Eclipse biner proved too strong for the test Machine. The biner went to 33kn and promptly blew the seals on the pump. Apologies to anybody who came along on the Sunday to see the demo and was disappointed.
I hope that this clarifies our position sufficiently.
Chris Rowlands
Brand Manager DMM
It may well be me who you spoke to at the NEC, although I don't in all honesty remember the conversation, as I did talk to a very large number of folk, so apologies for that. However having read this thread I'd like to emphasise a few points.
We as a company need to err on the side of caution when offering advise on subjects such as this where there are so many variables and differing circumstances. Very often it is impossible to offer a hard and fast explanation. If I was asked a direct question such as 'Would you retire a carabiner if it were dropped from a route' I would have to say retire it as I don't know the damage that may or may not have been caused in this particular case.
Various people make valid points, such as verify the shape against another biner of the same sort, check for obvious signs of distress, see if the gate mechanism is still working smoothly, etc etc. However nobody can be 100 % sure it will be ok. As I said before there are so many variables, how high, what did it land on , did anything land on the biner in the fall etc etc.
Yes, we do have to cover our arses as somebody so succinctly put it.
No it isn't a subtle plot to sell more biners.
Yes we do err on the side of caution with advice, and quite rightly so. We have 120 peoples livelyhood at stake her in North Wales, and wouldn't want to jeopardise this with a hefty lawsuite. But much MUCH More importantly we don't want to risk anybody getting hurt unneccessarily by offering ambiguous advice that could lead to confusion.
Our Instructions State in relation to Lifespan:
'It is very difficult to estimate this due to local use and storage conditions, but a conservative estimate would be ten years for metal parts................. however the following might reduce the lifespan to as little as one use: Fall Arrest/General wear/ chemical contamination/corrosion/gate malfunction/mechanical deformation/distortion/ heat contamination (over normal climatic conditions)'
Ultimately it is down to the individual to make a choice. In this case the consequences of the wrong choice could be catastrophic. That's not alarmist, that is merely stating that the consequences could be catastrophic. They might not be, but is it worth the risk.
Interestingly, and on a personal note, I have been climbing since the age of 12, and I am now entering my 50th year. I honestly can't remember dropping that many biners, certainly not enough to make me think that replacing them would be a major issue.(even if I had to pay for them all.)
As an aside, at the show we had a tensile tester to demonstrate the strengths of various biners. We had to abandon the demo on the second day as an Eclipse biner proved too strong for the test Machine. The biner went to 33kn and promptly blew the seals on the pump. Apologies to anybody who came along on the Sunday to see the demo and was disappointed.
I hope that this clarifies our position sufficiently.
Chris Rowlands
Brand Manager DMM
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