Minimum Maillion Size for Rigging

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Minimum Maillion Size for Rigging

Postby Extremeophile » Jun 20, 2011 8:09 pm

I'm curious what size Maillion Rapide others would consider a safe minimum for rigging purposes. I generally always choose stainless for permanent rigging and I was a bit surprised when I saw that SS appears to be rated quite a bit stronger than galvanized for the same size. Although a 5 mm SS Maillion looks pretty thin it has a safe working limit of ~1,000 lbs and a breaking strength of ~5,000 lbs. I believe that makes it similar to the failure strength of most 3.5" x 3/8 bolts. So a 2 bolt anchor rigged with a pair of 5 mm Maillions would hold up to ~10,000 lbs. It seems most people use 7 mm or even 9 mm for connecting ropes to bolt hangers. I believe some may be concerned with the small radius of a 5 mm Maillion reducing rope strength. Other opinions?

http://www.onrope1.com/pdf/2006/Maillon_Rapides.pdf
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Re: Minimum Maillion Size for Rigging

Postby Scott McCrea » Jun 20, 2011 8:24 pm

The 5mm only has an opening of 1/4". Will your rope fit in it?
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Re: Minimum Maillion Size for Rigging

Postby Extremeophile » Jun 20, 2011 9:57 pm

Scott McCrea wrote:The 5mm only has an opening of 1/4". Will your rope fit in it?

That's a good point. The inside diameter is large enough, but the gate is too narrow to accept 11 mm rope. You would have to use a knot that can be tied by doubling back, so it won't work with a double figure-8 or double bowline. So maybe 6 mm is the more practical minimum.
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Re: Minimum Maillion Size for Rigging

Postby PeterFJohnson » Jun 20, 2011 10:09 pm

Extremeophile wrote:So a 2 bolt anchor rigged with a pair of 5 mm Maillions would hold up to ~10,000 lbs


I am not disputing the safety of those quicklinks, but the numbers above assume that you are rigging a true load sharing system, which very few people do in a cave.

That being said, some of the larger quicklink gates don't even fit larger diameter rope...
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Re: Minimum Maillion Size for Rigging

Postby NZcaver » Jun 20, 2011 10:18 pm

Scott McCrea wrote:The 5mm only has an opening of 1/4". Will your rope fit in it?

I agree this is a good point, unless you do a re-thread knot every time (which would be a PITA). I find those little ~5mm stainless maillons great for footloop attachments, pack strap attachments (on a Swaygo), and other little applications where it's nice to have something light and compact but with a fairly high rating if I ever need to improvise with it.

For fixed rigging, I'd probably go with 6mm minimum too. It would be nice if that On Rope chart listed proper metric specs instead of all this fractional nonsense :big grin: but I think 6mm should suffice. When using stainless you should be aware of possible binding/galling issues, as previously discussed here. Potholer from the UK posted a disclaimer about SS maillons from a caving equipment supplier website, but the link is now defunct. Here's what it said:

Be aware that the threads on stainless steel are prone to 'binding' and it doesn't take much in the way of muck to cause the collar to jam. Specialist stainless thread lubricants are available from industrial suppliers but they are very expensive. We would only advise the use of stainless steel if it is absolutely necessary. If the collar locks up this does not constitute a manufacturing defect, it is a trait of the material used and it's unsuitability to the caving environment. The only reason we sell the stainless version is for use in marine environments or permanent fixed rigging situations. For general caving use the ordinary mild steel one.
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Re: Minimum Maillion Size for Rigging

Postby PeterFJohnson » Jun 20, 2011 11:17 pm

NZcaver wrote:When using stainless you should be aware of possible binding/galling issues, as previously discussed here.


Perhaps, but what would be the alternative for quicklinks? Especially ones that are used in permanent rigging. Zinc Plated/Galvanized is often no good. Titanium?
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Re: Minimum Maillion Size for Rigging

Postby NZcaver » Jun 21, 2011 2:41 am

PeterFJohnson wrote:Perhaps, but what would be the alternative for quicklinks? Especially ones that are used in permanent rigging. Zinc Plated/Galvanized is often no good. Titanium?

Haven't seen titanium screw links, but I imagine they'd be a little too expen$ive for the average caver.

Read the quote at the bottom of my previous post again. It recommends stainless for permanent rigging, and non-stainless for most personal (i.e. on your person) applications. Personally I'm happy using the small rated stainless screw links for footloops and pack links as I explained previously, and I mostly use Zicral (aluminum alloy) for primary connections like my Petzl Omni and 10mm oval screw link connecting to my micro rack. YMMV.
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Re: Minimum Maillion Size for Rigging

Postby paul » Jun 21, 2011 6:28 am

I always use 7mm GO (Grande Overture) Maillons. Thes are what most UK cavers use for SRT rigging if not using carabiners - mainly because if the "Grande Overture" or Large Opening which makes it easy to get 10 or 10.5mm diameter rope in plus the strength (25KN when done up in the long axis so similar to a carabiner) when compared to smaller diameters.

They also have the benefit of fitting the screw-up part of the 10mm "D"-shaped Maillon most UK cavers use to connect their harness at the front so make a useful spanner (or wrench) to loosen or tighten the central Maillon. I use a 7mm GO Maillon for this reason to attach the Safety Link from my top jammer to my central Maillon in my Frog SRT setup for this reason.

I bought a few 7mm GO Maillon Rapides made from Zircal some years ago and when I saw that they were substantially weaker than the steel versions (10KN along the long axis when doen up as opposed to 25KN for the steel versions - see https://www.expe.fr/catalogue-sport/mousquetons-maillons-rapides/maillons-rapides-normaux-maillon-go-7-mm-zicral-c1_45_192-p819.html?language=en , I never used them for SRT rigging.
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Re: Minimum Maillion Size for Rigging

Postby PeterFJohnson » Jun 21, 2011 2:46 pm

NZcaver wrote:Read the quote at the bottom of my previous post again. It recommends stainless for permanent rigging, and non-stainless for most personal (i.e. on your person) applications.


I get an F for reading comprehension...
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Re: Minimum Maillion Size for Rigging

Postby potholer » Jun 22, 2011 11:30 am

The opinion I grew up hearing was that 7mm maillons were thought to be about the minimum for rigging, since passing rope over thinner bar could put unbalanced loads across the rope, and might lead to a greater strength loss than happened in knots.

I'm not sure of the source, since it just seemed to be the general wisdom a few decades ago.

Presumably it would depend to some extent on rope diameter (maybe someone who used 8mm rope could use thinner maillons), but possibly not by enough to make a meaningful difference.
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Re: Minimum Maillion Size for Rigging

Postby Jeff Bartlett » Jun 22, 2011 3:52 pm

7mm GO maillons are about the only thing I can fit 11mm rope into.

Also, the diameter of the bar is indeed a big deal -- is rigging into a 5mm maillon all that much better than just tying knots through the bolts? You know, like we're taught never to do? Maybe slightly, because it's a curved surface, but it can't be much. Of note, when talking about a rescue load (2kN), several references specify 10mm as the minimum diamater, which further leads me to believe that 7mm is the most appropriate size for sport caving:

Life on a Line, 2d ed. wrote:Never tie a rescue-loaded rope directly into a maillon that’s smaller than 10mm diameter. It’s not the strength of the maillon we’re worried about, it’s the effect such a sharp bend has on the strength of the rope.
"Although it pains me to say it, in this case Jeff is right. Plan accordingly." --Andy Armstrong
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Re: Minimum Maillion Size for Rigging

Postby jharman2 » Jun 23, 2011 12:13 pm

Extremeophile wrote:I'm curious what size Maillion Rapide others would consider a safe minimum for rigging purposes.


For exploration / push rigging we've been using 5mm SS links and 9mm rope. Once it becomes a trade route we switch to 7mm SS links and 11mm rope.
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Re: Minimum Maillion Size for Rigging

Postby Moff » Sep 22, 2011 4:01 pm

7 mm or bigger 'petzl GO' or analogs (Kong, Raumer) is what Russian and xUSSR cavers use for permanent rigging.
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