Fixe PLX HCR - "New"? Metal as alt to Titanium?

Brian in SLC wrote:^^^Wow...that's a wild looking mild steel bolt! I'd think between the usual concerns for a galvanic cell situation, and, the harsh environment, a carbon steel bolt wouldn't last that long. Things that make you go "hmmm"... Treasure trove of information...thanks Martin!! Edit to add: If you know that the bolt takes 40Nm of force to break with a torque wrench, could you estimate its shear strength? 40Nm of torque is really close to installation torque for a grade 5 fastener? Question is...would this bolt have held a fall? What kind of impact could it have taken? Can that be estimated? Sorry...my math skills are lacking this morning...

Brian, I was thinking the same about estimating the breaking force from the torque required to shear it off. I'm afraid I can't tell you, that's beyond my expertise.
One of the points for showing those photos was to show how shallow the rust was on the mild steel and how long a stainless hanger can actually last for in just one location in Thailand. Also to compare this to good quality stainless hangers failing with bodyweight in just a couple of years.
Did you see the bolt from Malta that is on page 4 of this thread? It looked far better than the one pictured above but failed with less than 40kg load.

Typical installation torque for 10mm bolt is 35Nm and 50Nm for a 12mm bolt.

John Byrnes wrote: I'll copy you on the email. I may be munching on my chapeau eventually, but I meant staying on the wall during a pull-test. I've seen total-crap bolts stay on the wall for 18 years if they're not stressed, but you can break them off with your fingers.

Thanks John.
I did pull those bolts to around 3kN~4kN in an outward pull and they stayed. They don't get any action though, they just sit on the wall, nobody falls on them and the torque drops off over time and nobody re-torques them until I do the next inspection. Some bolts dropped off to less than 7Nm in 18 months, some dropped off only about 10% and most loosened to around 50% of their installation torque in 18 months.
All the above are more reasons that glue-in bolts are better than expansion bolts

Martin Roberts wrote:Typical installation torque for 10mm bolt is 35Nm

Well....let's see. Recommended installation torques are around 75% of yield for a fastener?

35Nm would mean a yield at around 47Nm. Assuming 40Nm is the number...which is 85% or so of the strength expected in the fastener?

So, a 3/8" or 10mm diameter fastener starting out the shoot at, say, 8280lbf shear would be reduced to around 7000lbf?

Based on the lack of material loss of the fastener across its diameter, I'd expect it to be nearly full strength, so, 85% might make sense. And, assuming shear strength and % yield based on fastener torque is linear. Anyone?

Not bad for a 20 year old mixed metal fastener in a full on marine/humid environment!

There will be some who think that Slc is what?...a marine environment?

Brian in SLC wrote:If you know that the bolt takes 40Nm of force to break with a torque wrench, could you estimate its shear strength?

Sort of. To do the full calculation you are referring to, you would need more information on the exact diameter of the good metal, any stress risers created by pitting corrosion, and some more information on the torque wrench itself as it also imparts some bending moment along with the shear stress of torque.

However, my back of the envelope calculation says the bolt broke at ~66,000-psi shear stress which is inline with what the steel was likely originally rated too speaking to the comment that the bolt was not affected by SCC. Some more back of the envelope calculations with assumptions puts the bolt failing at around 4,000-lbs but it likely would fail at a slightly lower strength pulling on the hanger as that is not pure shear.

If you've lost 15% of the diameter you have lost 28% of the cross-sectional area which is what determines the strength of the bolt. So you would need to derate by 28% of original strength.

BTW, in the picture of the 316 Expansion bolt in the 'Thailand Long Term Corrosion Test', the installation of that bolt looks to be out of spec. I think the bolt shouldn't extend past the nut more than 1/2". That might affect the results of any pull tests.

TheIceManCometh wrote:BTW, in the picture of the 316 Expansion bolt in the 'Thailand Long Term Corrosion Test', the installation of that bolt looks to be out of spec. I think the bolt shouldn't extend past the nut more than 1/2". That might affect the results of any pull tests.

Why? If it´s a wedge bolt then it can stick out loads, I´ve a box on my desk which says 50mm sticking out and the longest ones in my suppliers catalogue allow 140mm. Standard embedment depth for 10mm bolts is 50mm and then they are just made longer to go through thicker things.

Jim: probably because I was generalizing based on what I see in Petzl's documentation here: petzl.com/sfc/servlet.sheph…

Here's a snippet from that document:

TheIceManCometh wrote:BTW, in the picture of the 316 Expansion bolt in the 'Thailand Long Term Corrosion Test', the installation of that bolt looks to be out of spec. I think the bolt shouldn't extend past the nut more than 1/2". That might affect the results of any pull tests.

The reason for that thread sticking out was because of softer than average rock.
If the torque was still rising then I continued to tighten until I reached manufacturers recommended torque.
This is another reason that supports the fact that glue in bolts are superior to mechanical expansion bolts

TheIceManCometh wrote:Jim: probably because I was generalizing based on what I see in Petzl's documentation here: petzl.com/sfc/servlet.sheph… Here's a snippet from that document:

That´s because Petzl only sell one length and if too much thread sticks out they aren´t conforming to the embedment depth, other companies sell longer bolts as well.
It´s better if they don´t stick out too far for sure to reduce the possibility of getting the karabiner hooked over but affecting the pull-out strength is unlikely. As Martin says sometimes you need to keep tightening until you get the correct torque, not all rock is equal.

Jim Titt wrote: It´s better if they don´t stick out too far for sure to reduce the possibility of getting the karabiner hooked over but affecting the pull-out strength is unlikely. As Martin says sometimes you need to keep tightening until you get the correct torque, not all rock is equal.

Well said Jim.
Biners snap very easily when accidentally wedged horizontally along their spine between the threads and the hanger itself (a picture paints a thousand words but 18 words doesn't really paint a great picture but I hope you understand what I mean!).
That's yet another reason why I think glue in bolts are superior to expansion bolts and hangers

Martin Roberts wrote: Well said Jim. Biners snap very easily when accidentally wedged horizontally along their spine between the threads and the hanger itself (a picture paints a thousand words but 18 words doesn't really paint a great picture but I hope you understand what I mean!). That's yet another reason why I think glue in bolts are superior to expansion bolts and hangers

Yes glue-ins are better than expansion bolts but for decent rock in a desert climate far inland, a good sleeve bolt with a nice hanger is good enough and this failure mode doesn't apply since there aren't any threads sticking out. Glue-ins are obviously superior for corrosion resistance but they're expensive, more difficult to use, and only usable for top-down bolting. I like ground-up FAs, drilled preferably by stance, or by aid in an alpine desert. Sleeve bolts and nice big fixe hangers work pretty darn well for that.

eli poss wrote: Yes glue-ins are better than expansion bolts but for decent rock in a desert climate far inland, a good sleeve bolt with a nice hanger is good enough and this failure mode doesn't apply since there aren't any threads sticking out. Glue-ins are obviously superior for corrosion resistance but they're expensive, more difficult to use, and only usable for top-down bolting. I like ground-up FAs, drilled preferably by stance, or by aid in an alpine desert. Sleeve bolts and nice big fixe hangers work pretty darn well for that.

You can use some cheaper non stainless removable bolts for the FA and then replace them top down with the glue-ins (and maybe in better spots for those leading to come). The price of good glue-ins is not that expensive (check out the Boltproducts twist ones (similar to Wavebolts but you can get them in heavier gauge if you want, which I like) compared to a good quality 1/2'SS expansion bolt and hanger. The glue ends up being maybe a couple bucks per bolt if you look around for a good price on the 8oz tubes of A7. So it costs me about $7 to install a good heavy gauge SS glue-in bolt, less than it does for a 1/2" SS Rawl and Fixe hanger nowadays. I could get exterior threaded wedge bolts cheaper, but I am not a fan of them so rarely use them.

M Sprague wrote: You can use some cheaper non stainless removable bolts for the FA and then replace them top down with the glue-ins (and maybe in better spots for those leading to come). The price of good glue-ins is not that expensive (check out the Boltproducts twist ones (similar to Wavebolts but you can get them in heavier gauge if you want, which I like) compared to a good quality 1/2'SS expansion bolt and hanger. The glue ends up being maybe a couple bucks per bolt if you look around for a good price on the 8oz tubes of A7. So it costs me about $7 to install a good heavy gauge SS glue-in bolt, less than it does for a 1/2" SS Rawl and Fixe hanger nowadays. I could get exterior threaded wedge bolts cheaper, but I am not a fan of them so rarely use them.

Again, I'm talking about a desert climate. I used 3/8" plated steel sleeve bolts. That's $4 a bolt, hanger included. And Glue-ins are harder to install and easier to fuck up.

I'm unfamiliar with that plx material but welcome its arrival. I'd be happy if they just quit selling plated steel (they call it PS) for anchors and hangers. http://www.fixehardware.com/shop/hangers/

Hi all,
This is not correct about the UIAA deciding to "ban 304." See quote below.

In fact in our latest classification, we would like/intend to have a separate class for Class 4.
Which in effect is 304 & equivalent.
Of the 5 classes.

In the earlier classification we were looking at, it is indeed true we were trying to discourage use of 304 by making the corrosion test harsh enough to exclude it.

But after the US-based contingent made some good points about it being a viable option for them, we thought it made sense to add it.

It's difficult to balance having a classification system that includes enough options, without getting too complex. That was our concern.

In fact in Europe, 304 is not used by the construction industry: they use only 316 for their standard outdoor safety-critical anchors. In effect 304 has been "banned" in all of Europe for anchors. In industry, the differential in material cost from 304 to 316 is shadowed by anchor manufacture costs, as well as labour costs. So they say let's not mess around, and for the extra cost of 316, let's benefit from its superior corrosion resistance.

We hoped to do the same.

But the issue is in the USA many manufacturers offer only 314, and not 316. And continental USA is quite different from Europe: there are indeed very large regions where corrosion is being, and 304 is fine.

So we thought let's accommodate this by including a "304" class.

Jim Titt wrote: Because I can go and climb on routes adequately bolted with steel bolts, some of the ones around here are probably 40yrs old and still perfectly serviceable. Cheapo plated Home Depot is one thing, forged steel ring bolts another. Steel generally doesn´t get SCC which is a big plus! The entire Mediteranean isn´t plagued with SCC, I don´t know of a single example of a bolt failing from SCC when it was made of properly treated 304 or 316. What plagues the Med is innumerably bolts made from sub-standard materials which fail from all sorts of corrosion, there are at least four manufacturers guilty of putting on the market bolts which have been subsequently found to be made of material not to the required specification, this the UIAA then use as evidence that SCC is rampant in 304 and 316. For example Alan Jarvis decided to ban the use of 304 after a chainset made by Fixe failed at a climbing wall(outside) in Germany, the independent laboratory report showed failure was by SCC from unknown influences AND that the chain was not 304 or any known grade of stainless steel. All the well-publicised cases of SCC and rapid general corrosion have involved bolts which have been found to be made of inferior materials, not certified 304 and 316. The exception to this are some bolts which we found suffered from severe pitting due to the filler in the resin, something the proposals will do nothing to solve. The simplest solution is to let installers use their own judgement and experience to select the best solution. A UIAA safety label does nothing to help especially when it is confusing and unworkable. You yourself have written that you will make your own decision on what is suitable despite their proposals and the rest of us will do the same.

And Jim Titt is right here: 304 does work in some places. And even plain jane mild steel has worked: but after 50 years it can be a problem. And it's not always obvious WHERE it will have an issue. So our recommendation is to spend a bit more and be sure.

You need to be careful about determining what materials various manufacturers are using.
It's not so straightforward to analyze them with the portable XRF devices that some people have available.

For instance there are many grades of duplex stainless steel. They vary from the newer "lean" types (2101 etc), that can be cheaper than 316, but are SCC resistant. To the "standard" grades (2205), to the "super" grades (2507).

Here's a really good summary of the various grades:
British Stainless Steel Association - Duplex
Outokumpu Duplex

Duplex s/s is not 400 series (which is a 100% ferritic stainless steel grade).
Duplex is as the name suggests: a double alloy, a mix of two microstructures: austenitic (like 300 series) and ferritic (like type 400). All mixed together, like a patchwork quilt.

That's why it is magnetic: because it is half ferritic.

Simplistically put, it is resistant to chloride SCC in many uses because any cracks that start in an austenitic grain (a small area) stop when they hit the ferritic grains next to it.

And yes, it does have a lower corrosion resistance in general that the higher grades of austenitic stainless steels: the 6 Mo's. But then it's a LOT cheaper too.

It can have an issue with crevice corrosion, so you would need to be careful what grade of duplex you used in an application where crevice corrosion was possible/likely.

WarthogARJ wrote:It's difficult to balance having a classification system that includes enough options, without getting too complex.

Exactly, as you say 304 and steel have worked satifactorily and there are well over a dozen materials that have been used in bolts that I can think of which have their place. So the UIAA answer is to dumb the standards down and prevent any creativity in the market DESPITE it being clear that the persons best able to judge a materials suitability are those with experience of their area.

WarthogARJ wrote:You need to be careful about jumping to conclusions about what various manufacturers are using. And it's not so straightforward to analyze them with the portable XRF devices that some people have available.

Which makes one wonder why the standards have never required the material used is declared so customers can decide it´s suitability for themselves.
I too could "invent" a proprietry name for any old crap and then make vague claims about it, commercially it´s a useful tactic because I can then change the material anytime I like and no-one has any come-back.

Jim Titt wrote: Exactly, as you say 304 and steel have worked satifactorily and there are well over a dozen materials that have been used in bolts that I can think of which have their place. So the UIAA answer is to dumb the standards down and prevent any creativity in the market DESPITE it being clear that the persons best able to judge a materials suitability are those with experience of their area.

The UIAA is not in fact trying to "dumb" down the standards. The UIAA Corrosion Standard Revision is trying to have a reasonable and consistent classification of anchors.

And it won't be based on material types, but on their relative resistances to SCC and corrosion.

Class 1: Very aggressive SCC/corrosion
Class 2: Severe SCC/corrosion
Class 3: Moderate to Severe corrosion (no risk of SCC)
Class 4: Moderate corrosion (no risk of SCC)
Class 5: No specified resistance to SCC/corrosion

There are NO materials mentioned there.
We are going to have lab tests that rank ANCHORS for their ability to resist SCC/corrosion attack.
A given anchor, warts and all, will be put through the various tests.
So it will consider material type, heat treatment, surface finish, welds, internal stresses etc etc.

We are NOT going to classify just the MATERIALS.

We will not classify locations in the standard: that will be done in a Recommended Guideline.
It's NOT a "Standard" for classifying locations, because unless you are making climbing cliffs (like a god) you cannot control it, you are merely categorizing it: in many cases by experience.

The idea is that people can match a location class with the appropriate anchor class in order to get a satisfactory pairing. As they say "horses for courses". If it turns out some anchors haven't worked there, you can use the next higher class.

To make things easier to follow, we have some examples of materials that we think will pass the tests in each class:
Class 1: titanium and 6Mo stainless
Class 2: stainless steels with a PREN > 35 (like 904L, Duplex 2205)
Class 3: 316(L)
Class 4: 304(L)
Class 5: anything that satisfies the other parts of the standard in terms of strength etc.
So it could be a coated anchor, or mild steel.
The manufacturer can specify where it should be used, and its corrosion/SCC resistance.
It's up to the end user to decide: as it always has been.

But the classifying test/lab doesn't need to know what the material used is in order to classify the anchors for a given Class.

In effect, we want to have a common "language" for people to be able to use to describe an anchor: Class 1 thru 5.
And if they believe that based on knowledge of their climbing area's SCC/corrosion, they don't need very much corrosion resistance, then they can use Class 4.
And can use Class 5 anchors.

There is nothing to stop the manufacturer from disclosing what material they make their anchors from. Or from people testing them, and finding out. There are not that many anchors, pretty soon it will be common knowledge.
Perhaps the UIAA standard should recommend that, I can suggest it, and see what others think.

Jim: you've made some good points when we've discussed this sort of thing. As have others.

Someone can take a "good" material, like 316, or Duplex 2205, and mess up its ability to resist attack.
Just by poor welding, bad surface finish/prep after processing, extremely high internal stresses etc etc.
You yourself say this.

Jim pioneered the use of Duplex 2205 for resin anchors: good for him. And he told me that he would prefer not to use welded 2205 in an aggressive environment. This shows he is knowledgeable of the potential issues.

But not all manufacturers are, unfortunately.

In the past, we have indeed left the SCC/corrosion resistance entirely up to the manufacturers. ANY manufacturer, even ones without any great corrosion/SCC competence.

And how has that worked out?
I'd say not that well.
The bulk of manufacturers agree with this too, although not in how to address it.

At the recent Berlin meeting of the CEN Technical Committee, a revision to EN959 was proposed that would classify anchors by THREE Classes, specified by MATERIAL alone.
The manufacturers who attended wanted this.

The proposed EN 959 classes are:
Class 1: Titanium and "HCR" (specified by a short list)
Class 2: 316(L)
Class 3: indoors (galvanized etc)

In fact it HAS banned 304.
There are no tests.
No check on whether of not the actual ANCHOR was manufactured well in terms of SCC/corrosion resistance.
And materials not listed can only be used if the manufacturer can show that they are equivalent or better than the ones already on the list (but there is no method/criteria/test specified for HOW to do this).

The UIAA, or at least some of us, and the materials experts in our Working Group, think this is a bad idea.
In any event, it is going to take a year or two for this EN 959 revision to work its way through the approval process: I suspect that knowledgeable materials people will point out its flaws, and it will die.

In other words we can carry on making whatever we want and customers can buy whatever they like:-)
In fact I´m dropping 304 from production anyway (even though I sold some today) because it´s just a hassle having two grades which do effectively the same thing.