Came across these interesting vid's from our sister organisation the BMC on resin bolts, I always wondered how it worked. I assume we use a very similar method in caves.

https://www.youtube.com/watch?v=s6kXM_q3lfk&pp=wgIECgIIAQ%3D%3D&feature=push-fr&attr_tag=Aimg8NEFp5C0Gh4N%3A6

Something that video doesn't talk about but is really important is pull testing. Its a lot easier to mess up a resin bolt install if you don't clean the hole properly, bolt products have a good breakdown of this. I know the DCA go around every bolt pull them to a specific load (i don't remember what the number is) after install to check. I'm sure other regions do this as well.

" I know the DCA go around every bolt pull them to a specific load (i don't remember what the number is) after install to check. I'm sure other regions do this as well."

Hmmmm, think again.
I've always had an issue with this, and questioned before why it is not done for every installed bolt.

Tseralo said:

Something that video doesn't talk about but is really important is pull testing. Its a lot easier to mess up a resin bolt install if you don't clean the hole properly, bolt products have a good breakdown of this. I know the DCA go around every bolt pull them to a specific load (i don't remember what the number is) after install to check. I'm sure other regions do this as well.

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As far as I know, no anchors are ever pull tested in climbing (except where they are testing bolts)?

The vast majority of climbing anchors are installed by climbers. There is no centralised record of anchors, they are paid for by climbers or bolt funds, and climbers are free to use whatever anchors they want. Seems to work pretty well though, generally, as climbing is good at self-policing (and self-reliance when choosing routes and anchors).

It should be pointed out that climbing/mountaineering anchors are not intended to be pull-tested; it is not part of the standard (unlike industrial anchors which are intended to be pull-tested). It is acceptable for a climbing/mountaineering bolt to exhibit permanent deformation at the 6kN typically used for pull-testing, as long as they don't fail until the 15/20/25kN (can't remember which) they are supposed to hold. The standard is for a bolt that goes in with a higher margin of safety than an industrial anchor, but is then never tested. Climbing must use thousands, if not hundreds of thousands of times more anchors than caving globally; caving is a very niche use.

Equally DCA are very happy that for the anchors they use there is no damage or deformation during their pull-testing. I'm perfectly happy either way, especially since anchors should always still be redundant no matter how good they are (which isn't _always_ true for some resin-bolted caves unfortunately).

Cavers insist on doing it a 'different' way though (designing their own anchors, doing their own testing, not following the manufacturers guidelines/recommended resins etc for using commercial bolts)... Some of this is because caves are wet, some of it is just because cavers (hence the regions all doing their own thing despite there being individual climbers, e.g. Gary Gibson, who have probably put more anchors in themselves than all regions combined do in a year!).

Tseralo said:

Something that video doesn't talk about but is really important is pull testing. Its a lot easier to mess up a resin bolt install if you don't clean the hole properly, bolt products have a good breakdown of this. I know the DCA go around every bolt pull them to a specific load (i don't remember what the number is) after install to check. I'm sure other regions do this as well.

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6kN applied directly out (axial) for 15 seconds. This proves the resin has set correctly and bonded to the rock/anchor and that the placement is strong enough to hold any load that could be placed on it if used correctly for SRT with a good safety margin. Unlike in 'industry', we do not test the anchor on a regular schedule, just the once after placing and before first use. We always retest anchors that have been reported loose and pull them out if necessary. This is very rare by the way and does seem centred on a specific period of installs around early/mid 1990s.

I can hear a can of worms cracking open at the question of who tests anchors after installation and why. It is not universal. DCA have chosen to do this as we feel it is right to do so and it helps identify that 1 placement in 100 or so that goes into a bit of cracked rock or a hidden spar scrin etc... that cannot be detected at the time of placement.

Yes this is a can of worms.

Most anchors do flex (as opposed to distort - that starts to occurs around 10kN) when tested even at 6kN.  BCA found that because resin often was located up onto the head, then cracking of the resin occurred during a test.  Soon after testing was initiated in the mid 2000's BCA got a moderate number of reports of damage to resin which was quickly linked back to testing.  E&T decided to cease testing.  DCA found some way of minimising the flexing (though I never understood how) to avoid such cracking.  So they reinstituted testing for newly placed anchors.  It does provide some 'comfort' information on whether the hole was adequately cleaned but not against most rock or metal problems.  No other region continued with testing, either after placement or following a report. 

Cavers first chose the DMM Eco anchor back in the 1990s and had considerable success with the program across the UK funded by NCA and then BCA.  When DMM ceased manufacturing the Eco anchor, BCA did try to get its own manufactured but ran into metal problems (the metal cracked at circa 15kN loading).  BCA ended up with the Bolt Products twisted leg anchor being the only one found on the market at that time.  CSCC object on conservation grounds to the twisted leg as it often causes a lot of cracking in the rock when the anchor is extracted using a simple pull and thus destroys the location.  Simon Wilson developed the IC resin anchor which avoided this concern.  But the manufacturing technique is time consuming.  Thus the limited stock is only available for use in the Dales.  CSCC allegedly did some trials on alternative anchors but no information was released. 

An alternative design to the IC anchor was worked up but not manufactured or tested.  If someone would like to take this forward, then PM me.  Perhaps there are better designs on the market; I have not looked for several years as there has been no interest within E&T to push it forward.

It is worth keeping these debates in perspective.

As far as I am aware there have been no actual failures of any resin anchors placed in the UK under the BCA scheme since its inception. This includes DMM anchors, BP anchors, IC anchors and at least 3 different resins as the program has evolved, as well as regions where they have been tested and regions where they haven't. Given that no single anchor should be relied upon in use, that leaves cavers in a pretty good position.

We can debate testing ad infinitum, e.g. can the testing crack resin, can we justify not testing, what about placements where testing is physically impossible, etc. The evidence from the large sample size of anchors across the UK seems to be that it is neither detrimental, nor clearly necessary, to carry out tests. Even loose anchors, although not necessarily measured, tend to take a massive force to remove.


With my pendant hat on, they are anchors, not bolts 

MarkS said:

Given that no single anchor should be relied upon in use, that leaves cavers in a pretty good position.

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If anything, I feel that is the bigger issue and not the minutiae of perfecting the anchors themselves.

In many places, anchors are placed such that it is impossible to rig correctly using them. Cavers are then in a situation where failure of a single anchor could be fatal. But we all know it doesn't matter, because resins don't fail.

I would rather we were less obsessively technical about our anchors themselves, and more obsessively technical about their placement and usage. That way, habits that riggers form when using resin anchors will not put them at risk when they are rigging from less bombproof anchors -- such as on an expedition.

Mike Hopley said:

In many places, anchors are placed such that it is impossible to rig correctly using them.

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If you think this is the case, certainly raise it with your regional council.

Mike Hopley said:

Cavers are then in a situation where failure of a single anchor could be fatal. But we all know it doesn't matter, because resins don't fail.

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It doesn't have to be the resin that fails. The whole wall gave way on the bottom pitch in Little Hull Pot, taking the intact P-hanger used for a deviation with it.  Nobody was around at the time.

Agree completely with MarkS. These discussions are good but need to be kept in perspective to avoid getting carried away.

The CNCC region has of course placed several hundred resin bonded stainless steel anchors since the early 1990's and does not consider it necessary to test an anchor in a cave after placement (although of course there is a lot of testing gets done outside of the cave before that type of anchor is approved for use, and installers are trained to ensure good practice such as cleaning the hole out).

The CNCC has a very clear message to anyone caving using resin bonded anchors: https://cncc.org.uk/fixed-aids/safety.php

In summary, all users should check each anchor before use, and never rely on a single anchor.

Having been on a trip where a P-anchor with a little bit of movement was pulled out, the force required still took me by surprise (and those forces were of course straight outward, not downward). It really did not come willingly... it nearly broke the puller (in fact, after removing it, I jokingly commented that the anchor was fine after all and we should have left it in). It is also worth noting that of the anchors in the Dales with slight movement, this has been partly attributed to resin shrinkage over time and not an incorrect initial placement. These issues have been rectified with the IC anchors which use smaller holes, and newer generation resins.

But... these kind of discussions are always useful to share thoughts, and the experience/knowledge of people like Bob, Pete and others is great to share.

Regarding anchor placements... I hear a lot of general criticism about the placement of some anchors (too high, too low, too far apart, too close together etc). Most of this is just general banter with no real criticism intended, although when I was CNCC Secretary I did find myself at the wrong end of a few cavers' rants now and again. Often this is done without considering a number of factors such as the practicality of the installation, the availability of appropriate quality rock (there is a lot of poor quality rock at some pitch heads), the fact that the placement might consider higher water conditions, the accessibility of the site for a person holding a heavy drill, the limitations of the anchor/resin used at the time, or simply the personal opinion of the installer.

Not to say there aren't some questionable placements (there probably are)... but there are lots of factors to consider

The far greater risk from vertical caving stares at you every day - in the mirror!

MarkS said:

If you think this is the case, certainly raise it with your regional council.

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Perhaps I should (though I don't care much about the bolts in Surrey...). But to be perfectly honest, I feel this is a case of "choose your battles".

I would like to import the French rigging philosophy into UK caving practice. But I don't realistically see this happening, and starting a one-man crusade doesn't seem a good use of anyone's time. The current situation is "good enough" in practice, at least with resins.

I'm not looking down on anyone here by the way. I have a great deal of respect for people who do this work, and it's easy to pontificate about technicalities when I'm not actually doing the voluntary work myself...

langcliffe said:

It doesn't have to be the resin that fails. The whole wall gave way on the bottom pitch in Little Hull Pot, taking the intact P-hanger used for a deviation with it.  Nobody was around at the time.

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Indeed, that does seem to be the only way resins "fail" (well, that and corrosive environments).

I'd say if the entire wall collapses, you're in a pretty bad spot regardless of how good the bolting was.

Pedantically, there have been several down cave I am afraid and more in other circumstances.  The first was where the anchor was placed in what turned out to be a bolder which fell down the pitch, again fortunately when no one was around.  Rather like the Little Hull Pot example.  Then because of the testing program one anchor was deemed failed because the placers had put it in a flow stone covered rock and due to testing, the flow stone had cracked. 

As an aside that was the impetus for ceasing testing (apart from the access challange of fitting a tester into the limited 'head room' above the anchor due to the other wall).  Also there had been an extensive inspection program for over 10 years which had not revealed any failures.  Reported defects were invariably found to be the reporter confused flexing of their fingers with movement of the anchor but in a few instances, that the anchor was loose.  But as CaveMatt said, they were found to be bloody difficult to extract.  As a consequence it was agreed by E&T in the late 2000's to cease the routine inspection program and rely solely on cavers inspecting the anchors prior to use. 

The oft reason for lose anchors was the rock to resin chemical bond had failed so as to permit some degree of movement.  This was vividly brought home when on one placing trip, those placed were subsequently found to not be secure.  That was traced back to the installer using a squeezy detergent bottle to wash out holes but had not thoroughly cleaned out the detergent before use!  I have also had anecdotal information indicating that other persons fail to properly clean out the hole after drilling.  So the possibly most significant point in the whole placement process is clean the hole by repeated washing and brushing and then blow the water out.  It should be noted that even if the resin to rock chemical bond goes, because the hole is deliberately drilled to be rough and undulating, there remains a good mechanical bond.

On the topic of using single / two anchors, it should be noted that this only applies to the pitch head, rebelays and deviations usually have one.  But I am not convinced about the wisdom of that given the potential for damaging peak forces from even small drops on SRT ropes.  Though there has only been one serious incident I am aware of where the guy's back took most of a year to recover.

Also, it is worth noting that the choice of resin is critical.  Climber usually place anchors on dry days; cavers in almost always wet or damp conditions.  So BCA has done a lot of work on choice of resin to ensure it can cope with wet conditions.

I should disclose that I have never been an installer but have gained much of my knowledge from Les Sykes and Glenn Jones who were part of the team that drove the process from the start.  I have spent a lot of time recording their pearls of wisdom and others into the E&T minutes between roughly 2005 and 2015. 

One other parameter to consider when testing is done is that the pull-testing rig can actually get into the space to do the test. We had one last year that needed the unit extending with shackles to reach the damn thing - which was placed perfectly for abseiling, I should point out. It passed fine, but it took over 30 mins between two of us (on separate ropes from temporary screw-in anchors) to actually arrange the rig to do it to satisfaction. So I'll definitely bear that in mind in future. On the rare occasion like this, I guess the benefit of a perfect placement may have to override the benefit of pull-testing, as long as the anchor is flagged as such.

Bob Mehew said:

On the topic of using single / two anchors, it should be noted that this only applies to the pitch head, rebelays and deviations usually have one.  But I am not convinced about the wisdom of that given the potential for damaging peak forces from even small drops on SRT ropes.

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Indeed, at least when single-bolt rebelays immediately follow the previous anchor. It's also worth noting that rebelay failure when you are about 1 -- 3 metres off the ground sends you smacking into the floor in a very bad way.

Deviations are generally mild in terms of peak forces, the issue would more be "what do I smack into?", "will I drown under a waterfall?", or "what happens to the rope above me?"

The other main problem I see here is traverse lines that only start with a single anchor. There are always two anchors at the "scary end" of the rope, but that doesn't make the approach safe -- at least not for the rigger / de-rigger.

Mike Hopley said:

I'd say if the entire wall collapses, you're in a pretty bad spot regardless of how good the bolting was.

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It is in a fault chamber, but I never thought  that the P-hanger was in an unreasonable place, although I was never that keen on the overall approach to the bolting of that pitch. The new rigging is a lot better.

What have I started lol. Well still the discussion is very interesting read.

langcliffe said:

It doesn't have to be the resin that fails. The whole wall gave way on the bottom pitch in Little Hull Pot, taking the intact P-hanger used for a deviation with it.  Nobody was around at the time.

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Moot point because its not bolt specific, that could happen with any kind of bolt, resin, expansion, etc.

to combine some interesting aspects from industry and caving anchors

In industry it was understood that a straight out pull test did not reflect fall protection applications, but the pull test did confirm that the anchor would remain in situ such that you could predict that it could cope with the shear force you wanted.
This assumed the material and bolt were capable.
Where the load was to placed directly then the adhesion became a greater part of the mechanism to resist he force and so needed more careful consideration, but in reality was less common - however many poorly informed installers simply carried out testing / installation assessment as if it was to be used in shear.

In a caving situation and especially with a Y-hang the forces will be predominantly downward, but will depending on the angle be outward so in theory a loose anchor may get some encouragement to start walking out - but as matt said it does take some force to get the anchor past all the irregularities within the hole.
The next thing to consider is a deviation anchor where the force is predominantly outward, but in many positions is probably not taking as much force as the main anchors, plus the consequences of failure may be less. there will however be some instances of a deviation close to the main anchors where the angle is maybe more extreme and then the consideration of it placement and the rock should be assessed carefully.

Overall a fascinating subject, but we should all take our hat off to those who have put a lot of effort in setting up our sport for widespread SRT providing us all with amazing opportunities and with a great safety record.