Maillons, WHY?

[Bottlebank]

Not a big fan of triple action or twistlock in caves, they're fine when shiny and clean but fiddly when full of mud

 

[Mike Hopley]

ah174 -- I feel the same way. I much prefer rigging with carabiners. If you can afford them, go for it.

But as people have already said, maillons do have their advantages. Most importantly they are cheaper. If you're buying 150 connectors for an expedition, that would be about ?1080 of the carabiners I prefer. Or you could pay ?450 in maillons (both these prices could maybe be reduced by bulk).

Steel connectors are clearly better for long-term placement.

I think people may be worrying too much about locking carabiners rotating. Obviously it's something to be aware of, just as you want to watch out for loose bolts or hangers (as Mark mentioned). It seems the French, and probably others in Europe, are moving towards "carabiners by default", as convenience gradually wins out over cost.

 

[Mark Wright]

Bottlebank makes an imortant point about mud getting into the mechanism of a triple action carabiner. I use a Petzl Omni Triact connector on my harness and I always have to pay special attention to making sure it closes properly when I put the harness on in a muddy cave. Once they are locked they won't come undone but they can be a bit fiddly.

Although I've got about 100 x 7mm 'long' Maillon Rapides, these days I usually use carabiners for rigging UK caves because they are easier. I don't have too much of an issue with bulk as I usually get somebody else to carry them!!

Mark

 

[Mike Hopley]

I use a Petzl Omni Triact connector on my harness and I always have to pay special attention to making sure it closes properly when I put the harness on in a muddy cave. Once they are locked they won't come undone but they can be a bit fiddly.

Mine actually did come undone after being locked, and it was outside the cave and brand new when I put it on.

Later testing revealed that, when my harness was loaded, the webbing loops pressed in on the Omni so that the first lock stage was undone. The second lock stage is a twist, and that was probably held undone in a similar way, and then later made "permanent" by some grit entering the mechanism.

When I removed the grit and lubricated the Omni, it became unstuck. But it was still prone to at least the first locking stage being undone, pretty much every time I got on rope.

I haven't heard of anyone else having this problem (although it is easy to miss). It may be a peculiarity of my body or my harness.

 

[ah147]

Maillons may also be smaller than biners, but they are also heavier than many modern locking biners.

My rule of thumb is rigging long term? Maillons, everything else? Biners.

As much as everything else it is faster, if I forget to do one up it loses no strength at all, etc etc etc

If the French are using them exclusively now however, I'm sure we shall be soon.


Sent from my iPhone using Tapatalk

 

[Mark Wright]

Mike,

Thats an interesting story about your Omni Triact. I've been using one since they first came out a good few years back and have used it in some pretty muddy caves but have never had it come undone on me as you describe. I've not heard of any similar problems with them in the industrial arena either. I use a Petzl Superavanti harness, what harness was you using when it came undone?

Mark 

 

[Mike Hopley]

Mike,

Thats an interesting story about your Omni Triact. I've been using one since they first came out a good few years back and have used it in some pretty muddy caves but have never had it come undone on me as you describe. I've not heard of any similar problems with them in the industrial arena either. I use a Petzl Superavanti harness, what harness was you using when it came undone?

Mark

Hi Mark,

I was using an MTDE Picos harness. The webbing loops are quite substantial and tight, and it's such a different "shape" from a Petzl harness that they could definitely behave differently.

It was slightly alarming to realise, as I took off my SRT kit, that I'd just climbed ~650 metres with a snaplink carabiner holding my harness together. Then again, I know people who have climbed more than that with an open maillon. 

Just like you, I've never heard anyone else having the same issue. From all other sources than my own personal experience, the Omni would seem to be a very secure piece of kit. And of course, Petzl will have tested it extensively.

I do like it, and it also prevents the "start chatting / helping other people with their kit and forget to do up your maillon" hazard. I might give it another try, and see if I can get it to stay put.

 

[Mike Hopley]

Oh, I should also clarify this:

I'm pretty sure that, when I was taking off my SRT kit, the Omni was totally unlocked.

However, once the Omni was off the harness, I am not entirely sure how unlocked it was. The first stage (push) was definitely disabled, and I remember needed to remove grit and lubricate it before it would auto-lock again.

But the second stage (twist) -- I'm honestly not sure. I think it might have been partly disabled.

 

[topcat]

Having spent most of my adult life so far falling off / hanging off and using krabs for mountaineering I'm happy to use them for rigging caves.  My fingers are pretty stiff these days too and I find  screwing Maillons very hard: krabs screw much faster and with less resistance.

Weights:  My screw gate Grivel Plumes weigh 38g  22kN
                7mm MR steel weight is 61g

[Random selection from my rack]

No contest really.

 

[droid]

I've tended to use maillons for sinle loops, and steel oval screwgates for multiple loops. But that was years ago.

 

[Mike Hopley]

I've tended to use maillons for sinle loops, and steel oval screwgates for multiple loops. But that was years ago.

Yes, GO maillons can get pretty cramped with more than one rope inside them.


[insert generic caution about lightweight rigging here]

For really lightweight rigging, it's worth remembering that Petzl Speedy alloy maillons weigh only 23 grams, and have a nice shape for clipping (compared to a GO maillon).

They live up to their name, taking just a few turns to open and shut. They are a bit like using a very light snapgate carabiner, but I reckon they are more secure. And they are certainly more compact.

They make lovely wind chimes clipped as a bunch to your chest harness; but also, being speedy, they have a reputation for quietly unscrewing themselves as you tramp along, and then mass-suiciding themselves into an inaccessible crevice.

 

[Mark Wright]

Mike,

I'm not familiar with the MTDE harnesses so can't really comment on their compatibility. The Omni Triacts work well with the two Petzl caving harnesses though. The Omni Triacts have a quoted Breaking Load of 20kN along the major, spine (gate) axis (Min. allowable for the EN standard is 15kN), 15kN across the gate and 7kN along the spine with the gate completely open so as long as your harness is a snug fit you should still be OK even if the Triact did completely open. Not an ideal situation though.

Petzl and DMM carabiners generally have a Breaking Load which is between 10% and 20% greater than the quoted strength. DMM actually manufacture the Petzl Freino carabiner as well as the Reverso belay devices. If Petzl had a carabiner that failed at only e.g. 6% stronger than that quoted they would scrap the entire batch! Every carabiner that Petzl manufacture is individually proof loaded as well as being subjected to regular destructive testing. I had a tour of the Petzl factory with Bob Toogood a couple of weeks ago and the quality controls they have in place are way ahead of other manufacturers which is why Petzl gear is usually a bit more expensive. You get what you pay for.

I remember working on a block of flats back in the 80's and Chris, who I'm sure a few on this forum will remember, did not pay attention to screwing up his central 'D' Maillon Rapide on his harness after returning to work after lunch. To cut a long story short, Chris took about a 5m fall onto his Petzl Stop descender and almost straightened the Maillon Rapide it was attached to via a short cow's tail and carabiner. The home made workseat he was using snapped in half! The threads on the Maillon Rapide had dug into his cow's tail material and the screwed sleeve had somehow jammed against his harness webbing and held the fall. He was quick to link a number of carabiners he had on him to make his harness safe and immediately abseiled to the ground, where he then took the rest of the afternoon off. He was very lucky.

On the point of abnormal loading. I was at a Lyon Equipment technical symposium a few years ago and a group of Arborists were demonstrating some of the issues they had with rigging pull-throughs around branches for access and egress of a tree. They showed an alloy 35kN carabiner to fail at around 0.375kN when being abnormally loaded. Effectively trying to bend the carabiner in half. Very worrying. Most Arborists use a 'Cambion Saver' system to eliminate the problem these days. In the rope access industry we would generally use a Maillon Rapide for rigging a pull-through system unless the ropes could be rigged around the structure in such a way that there was no possibility of abnormal loading of the connectors.

Be very careful with the Petzl Speedy quick links. They fall well short of the standards required of EN362(Q) which is what the Petzl Go quick links conform to. They used to include a Petzl Speedy with one of their adjustable footloops and the alloy screwed sleeve would soon wear allowing the sleeve to undo itself very easily. Getting mud in the threads will wear them out even quicker. 

Mark

 

[rsch]

On which note, having previously done the DMM factory tour, I can throughly recommend it for anyone who has more than a passing interest on where all those bits of kit come from.

http://dmmclimbing.com/news/2013/01/dmm-factory-tour-vid/

 

[Mike Hopley]

The Omni Triacts have a quoted Breaking Load of 20kN along the major, spine (gate) axis (Min. allowable for the EN standard is 15kN), 15kN across the gate and 7kN along the spine with the gate completely open so as long as your harness is a snug fit you should still be OK even if the Triact did completely open. Not an ideal situation though.

I'm not really concerned about the breaking load with the gate open -- as you say, these things are strong even in that situation. I am more concerned about potentially slipping out of my harness!

I had a tour of the Petzl factory with Bob Toogood a couple of weeks ago and the quality controls they have in place are way ahead of other manufacturers which is why Petzl gear is usually a bit more expensive. You get what you pay for.

I have the utmost respect for Petzl's quality control. They are a class act.

I remember working on a block of flats back in the 80's and Chris Rhodes, who I'm sure a few on this forum will remember, did not pay attention to screwing up his central 'D' Maillon Rapide on his harness after returning to work after lunch...

I have done that a couple of times myself. It is surprisingly easy to do when you are interrupted or distracted. This is definitely a point in favour of the Omni et al.

On the point of abnormal loading. I was at a Lyon Equipment technical symposium a few years ago and a group of Arborists were demonstrating some of the issues they had with rigging pull-throughs around branches for access and egress of a tree. They showed an alloy 35kN carabiner to fail at around 0.375kN when being abnormally loaded.

Yes, they can be shockingly fragile when loaded badly. It's important not to load them badly.

In the rope access industry we would generally use a Maillon Rapide for rigging a pull-through system unless the ropes could be rigged around the structure in such a way that there was no possibility of abnormal loading of the connectors.

Good advice.

Be very careful with the Petzl Speedy quick links. They fall well short of the standards required of EN362(Q) which is what the Petzl Go quick links conform to. They used to include a Petzl Speedy with one of their adjustable footloops and the alloy screwed sleeve would soon wear allowing the sleeve to undo itself very easily. Getting mud in the threads will wear them out even quicker.

Yes, they are clearly an item for true lightweight rigging only and are far weaker than their steel cousins. They are not suitable for general use. They may be used by very experienced, small teams who are also using 8 mm rope, AS anchors, and all manner of scary rigging methods that carry some additional risk.

They are categorically not suitable for (e.g.) replacing a club's GO steel maillons, any more than a club would replace all its 9 /10 mm ropes with 8 mm ones.

Light as they are, I shall not be rushing out to replace my full-strength carabiners with Speedy maillons.

 

[Inferus]

I have no knowledge of the technical side of things but here we go with my opinion:
Dangling from a piece of sting in a spray lashed shaft I want to be getting on with the job not twiddling with a MR. On a dry shaft where I'm not getting cold or some other less hospitable place then I'm happy using MR's. They both have their uses in my opinion, probably (along with cost) why I have a mix of the two.

 

[Antwan]

For steels there is considered to be a fatigue limit - a stress  below which fatigue will not occur in a specimen that does not already have a notch. This is about half the ultimate tensile stress (the stress at which it will break at once).

The picture may be useful if it clearly shows the face of the broken end, but a description of the geometry when it was cyclically loaded would be more useful. At the moment I am struggling to envisage the situation with the figures you give.

I'm only on my first year of an engineering degree so I am a bit green but everything I have read so far puts emphasis on how little is actually known about metal fatigue, one thing though is that increasing either the load frequency or the load force increases the risk of fatigue.

I have done a quick sketch of the machine and put the picture in the PDF below, The machine is kind of like a one arm bandit operated stapler. An end loop coil locking machine, used for binding books. I worked out the minimum force used to complete the operation by dropping two apples in a box onto the lever at the hardest point in the cycle when the handle is almost at 90 degrees from start and roughly worked it out from Mass*Gravity*Height at about 5n and doubled it for just incase. I can operate the mechanism with one finger.

The lever was not done up with sufficient torque into the screw slot and thus was not making full use of the mechanical strength of the fastening. I know there would have been some force multiplier going on here but I'm unsure how to work this out and would consider it to be fairly negligible.

www.3peaksuk.org/yss/metal_fatigue_in_handle.pdf


Back on to the topic of Krabs Vs. Maillions,  watch the Krabs at a pitch head next time someone (either fat like me or witha very rough technique preferably) is prussicing and pay attention to the amount of flex in the Krab.

This research by the massechuset institute gives a table on page 15 listing how many cyclic loads of a specified mass it took to destroy standard D shape karabiners http://web.mit.edu/sp255/www/reference_vault/Fatigue_Presentation.pdf

It takes about 10, 000 loads of 8Kn which is reassuring, but the point I was trying to make to start with is remember how old your karabiners are if you want to use them for rigging, particularly pitch heads. which is why I would not like to see them in club stores unless its an affluent club who will scrap them after x-many years unlike maillions where if it looks okay, then it probably is

So yes, Karabiners may be accidentally loaded the wrong way and fail at very low forces through a number of means, Old well used karabiners may well fail without warning through fatigue. But if you look after your kit and replace it regularly enough and are careful with how you place it then that will probably be okay

Personally, I use a mix.

 

[Madness]

if I forget to do one up it loses no strength at all, etc etc etc

Unless it gets knocked against rock causing the gate to open momentarily.

 

[royfellows]

Back on to the topic of Krabs Vs. Maillions,  watch the Krabs at a pitch head next time someone (either fat like me or witha very rough technique preferably) is prussicing and pay attention to the amount of flex in the Krab.

What I have sometimes heard referred to as a "Condor Moment" after an advert for a brand of pipe tobacco

Plainspeak: Something to contemplate on

 

[Badlad]

I remember working on a block of flats back in the 80's and Chris, who I'm sure a few on this forum will remember, did not pay attention to screwing up his central 'D' Maillon Rapide on his harness after returning to work after lunch. To cut a long story short, Chris took about a 5m fall onto his Petzl Stop descender and almost straightened the Maillon Rapide it was attached to via a short cow's tail and carabiner. The home made workseat he was using snapped in half! The threads on the Maillon Rapide had dug into his cow's tail material and the screwed sleeve had somehow jammed against his harness webbing and held the fall. He was quick to link a number of carabiners he had on him to make his harness safe and immediately abseiled to the ground, where he then took the rest of the afternoon off. He was very lucky.

This story is worthy of a full outing.  These were 18 storey blocks in Brighton and the ropes were anchored to cradle bolts set well back from the handrails at the edge.  Before lunch the kids had been playing us up and swinging on the ends of the ropes.  To prevent this while we were in the cafe we had all pulled our ropes up 30ft and just tied them to the top railing with a hitch.  After lunch whilst chatting away Chris had overlooked this fact.  He calmly put his stop and shunt on the ropes and hopped over the railing.  As soon as he leant back, the hitch undid and he fell 30ft until the rope came onto the main anchors.  He had borrowed my home made workseat for the drop which was made out of 3/4 inch ply.  His impact snapped the seat in two and I remember watching in amazement as the de-laminated timber floated down to the ground while Chris hung there frozen, not daring to move.  I popped down to him to find his maillon as Mark described.  It was more like a hook, with a 3 inch opening, but still holding the harness together.  Chris cobbled together a repair with some of my krabs and descended to the floor in a fair amount of shock.  Just as he touched down the clerk of works for the council turned up to see how the job was going and as Chris was running the job he had to recover his composure pretty quick so that the client didn't cotton on to the near miss.

What I remember most from this episode was another lesson learnt altogether.  The day before Chris had received a severe blow to the head when a door had blown shut on him as he bent over in a doorway to pick up some drill bits.  He surely suffered concussion but wouldn't seek any medical help.  That lunchtime he failed to remember we had all tied our ropes up with a hitch.  The 30ft of slack rope at his feet didn't register as a hint.  If that wasn't enough the following day he drove straight through a set of traffic lights and had another accident.  I learnt that if you have a severe blow to the head you really do need to seek help.  Cheers Chris if you read this.

 

[ah147]

if I forget to do one up it loses no strength at all, etc etc etc

Unless it gets knocked against rock causing the gate to open momentarily.

If it's getting knocked against a rock it's either loaded, in which case it's not coming off the bolt.

Or completely unloaded, which means I'm not dying.


Sent from my iPhone using Tapatalk