• Photography Showcase

    A great selection of caving photographs to see!

    Many thanks to everyone who supports this ever popular thread. Why not join in if you have taken a shot you are pleased with? I'll pop some of my favourites up in notices from time to time - to cancel the notice, clck the X top right.

    Click here to see more stunning shots

Bouncing metal work

caving_fox

Member
Generally if it's basically looking ok I don't expect to replace any of my metal SRT gear (Stops when worn, croll if missing teeth, maillons and karabiners never unless deformed). We (eg not me) managed to bounce a maillon 20 odd m down a shaft yesterday. It looks unmarked, and still does up without any friction.

Would you use it?

Obviously if you'd dropped it from hand to the floor it would be fine. If you'd dropped it so far that it was nicked/damaged/bent you wouldn't (all of titan? - if you could find it again anyway). How far would you consider too far to safely use again?

Would you use it just the once to finish the trip you were on if it was the only option for continuing? (much more comfortable if it was the last Y-hang rather than single re-belay).

Is there nay testing data on metalwork?
 

Pitlamp

Well-known member
Maillons are relatively inexpensive, so I'd just replace it, if it was me. It can still get used with the digging toys (e.g. with a wire rope winch).
 
Maillons are relatively inexpensive, so I'd just replace it, if it was me. It can still get used with the digging toys (e.g. with a wire rope winch).
If it still does up I would reuse it.
A metal component can suffer damage that is not obvious to the naked eye, eg by repeated cycling below the elastic limit producing fatigue cracks, but after a one-off that still leaves it looking and working ok I wouldn't even consider replacing it.
 

Pitlamp

Well-known member
Do we have any metallurgists who might make useful comment here?
(I'm not a metallurgist but I've seen failed equipment a time or two.)
 

mikem

Active member
If you're not there then you can't say for sure either way - what it ricochets off or lands on will make the difference
 
If you're not there then you can't say for sure either way - what it ricochets off or lands on will make the difference
I am sure that is true if an item has internal components that will suffer damage at forces lower than those needed to leave a trace on the outside (like an old-fashioned watch, perhaps), but I don't believe that is true of a maillon.
 

pwhole

Well-known member
I remember bouncing ball-bearings on a ceramic tile floor in the changing-room at school and they used to bounce as high as a powerball, so I suspect the elasticity of solid steel is what would protect it in a fall.
 

SamT

Moderator
"you should immeadiatly retire dropped krabs due to micro fractures".

I've heard this 'rumour' loads of times.

Bit of googling and this is the most scientific bit of info I could find.

'In a test conducted by REI, thirty carabiner bodies (half ovals, half Ds) were each dropped six times onto a concrete floor from a height of 33 ft. (10 m). Following the drops, their open-gate strength was measured and compared to thirty control samples from the same production batch that had not been dropped. The statistical result was no loss of strength.

According to Chris Harmston, the quality assurance manager at Black Diamond, £I have test-broken hundreds of used, abused, and dropped biners (even some that fell 3000 ft. (1000 m) from the top of the Salathe Wall on El Capitan). Never have I noticed any problem with these unless there is obvious visual damage to the biner. While somewhat reassuring, this does not give you carte blanche to use carabiners that have been dropped a significant distance. Immediately retire any carabiner that is crooked, has deep indentations, or has a gate that doesn£t operate smoothly."

At the International Technical Rescue Symposium, 2000, Garin Wallace and Kevin Slotterbeck of SMC presented data on the strength of carabiners that had been dropped 27 or 54(m or ft - not sure) onto concrete or asphalt. One by one, they dropped 115 new, SMC locking D aluminum carabiners. Then they broke the carabiners, measuring the breaking strengths.

What do Garin and Kevin say about using climbing hardware that has been dropped? Retire your hardware if you drop it (they do work for a manufacturer, after all). What do their numbers say? The carabiners that were dropped were no weaker than the un-dropped carabiners. In fact, the average strength of the dropped carabiners was slightly stronger than the un-dropped carabiners, but the difference was not statistically significant (during the presentation a certain engineer from an unnamed airplane manufacturer in the Seattle area was heard muttering something about forge hardening). It surprised me that the dropped carabiners did not lose strength, because a number of the carabiners suffered significant damage to the locking sleeve and/or hinge, and gouges on the frame.'


The above quote can be found on numerous outdoor forums it should be pointed out, I guess I've just added UKcaving to that list.

I dropped a locking krab off Dow crag the other week, probably 20m or more. Its back on the rack and I have no qualms in using it.
 

mikem

Active member
I am sure that is true if an item has internal components that will suffer damage at forces lower than those needed to leave a trace on the outside (like an old-fashioned watch, perhaps), but I don't believe that is true of a maillon.
The question was how far is too far, my reply of "it depends" on factors that we aren't aware of (as keyboard warriors) still stands
 

andrewmcleod

Active member
Given that carabiners dropped off big walls (up to 1000m) that pass visual inspection have all tested fine, I don't think we need to worry about a 20m drop...

Either it passes inspection or it doesn't.
 

SamT

Moderator
The question was how far is too far, my reply of "it depends" on factors that we aren't aware of (as keyboard warriors) still stands

The first question was 'Would you use it',
My answer is yes.
The second question - how far is too far, is impossible to answer, but based on the only evidence I can find online, and whilst it veracity is not 100%, I'm reasonably confident that as has been said, krabs dropped massive distances have tested OK, thus the usual distances invovled underground, say 175m absolute max, it should, subject to inspection, be ok.

However, everyone is individual and has differing levels of tollerance, how long is a piece of string.
 
Last edited:

DługaLonża

New member
Hi everyone! This is my first post here, so I would like to say hi.
Do we have any metallurgists who might make useful comment here?
(I'm not a metallurgist but I've seen failed equipment a time or two.)
It just happens that I am metallurgist and I have got developed opinion about legendary "microfractures" in aluminium alloys.

I have done my own research, as part of my master thesis in college, where I was describing microstructure of samples from both new and old, many times dropped, climbing carabiners made from 7075-T6 Al alloy. Haven't seen any fractures under light microscope, SEM or TEM. Mechanical properties, as hardness or tensile strength were even slightly better in old ones. I can also tell, from my best knowledge, that this kind of behavior is highly unlikely in this type of alloy.

I would use dropped aluminium carabiner if it only works and doesn't show deformation.
 

Wardy

Member
Interesting post, but one thing springs to mind.
If you take more care and avoid dropping things, then you never have to consider any of this!

A well known rope access trainer, who posts on here, once told me - I don't drop things, I am a rope access technician - simple.
It always stuck in my mind and in 40 yrs of caving I don't remember dropping a biner down a pitch - its sort of part of your skills.

On that basis then, if I did, scrapping it would be no big thing as it is not a common thing.
The minor saving if I used it is unlikely to be worth any risk, no matter how unlikely.

So Caving Fox, this could be your one fluke or freak moment that proves your normal proficiency, so no big deal, but if its a regular thing and the costs are mounting.............
 

pwhole

Well-known member
I dropped my only cleaning rag down a 10m pitch last week after putting a resin anchor in above it, and had to abseil down to get it and prussick back up in record time before the resin went off. I didn't have a lanyard on that ;)
 

cavetroll

New member
I agree with Wardy, reduce dropping to an absolute minimum. You, your kit and your friends will last longer. Secondly I have a hierarchy of karabiners. They start as good for anything, then become good for somethings, then good for one thing, then binned. It's likely a big drop might downgrade a karabiner a rung or two on the ladder. Following Wardy's advice, I reckon this costs me £8 every 2-3 years - an order of magnitude cheaper than life insurance.

Finally I will say that many people still successfully use karabiners older than I am. The argument being metalwork doesn't seem to deteriorate with age. This may be at least partly true, but one thing that has changed dramatically is quality control. If it's super old, and I drop it, I'm more likely to dispose of it it than if it's relatively new and I drop it.
 

Cantclimbtom

Active member
If you can tolerate the very American (so sick bro!) delivery there may be something of interest here. Be interesting to hear DługaLonża's opinion of it as a metallurgist

 

rm128

Member
As Wardy says, the best course of action is to simply not drop things. I have to confess to reading this thread with interest, but perhaps also ever so slightly smugly, assuming that I had reached a point where I was careful enough to avoid dropping anything other than the occasional small stone. Then, on Wed... I dropped a krab down the 1st pitch in Hardrawkin while setting up one of the deviations. With this thread in mind, I spent the rest of the abseil wondering whether I would use it again or not. I decided I would probably relegate it to solely deviation or gear hauling duties, even though it was relatively new. Any such dilemma was avoided anyway by not being able to find it. If anyone does find it, feel free to use it as you see fit, or subject it to destructive testing.

On the positive side, I found a tape sling on the cascades between the pitches, presumably also dropped down the 1st pitch. I’m happy to return it if the owner reads this.
 
Top