Danger - Rhinos Rift

[Bob Mehew]

Four comments

First the effort required in removing an Eco Anchor from its resin leaves it fit only for scrap.

Second NCA purchased the remaining stock of Eco Anchors from DMM in around 2000.  I am not clear as to why DMM then decided to not make any more.  My guess, for what is worth, is that they found the Eco Anchor did not sell well enough to make it worth their effort and finance to offer for sell.  Market forces.

Third, yes Singing Rock anchor does have a CE Mark, but more importantly, it claims compliance with BS EN 795 and 959; 959 being the mountaineering anchor standard.  (BTW, although the anchor does not include the resin a spart of the anchor, the resin is part of the system for placing the anchor according to the BS.  So the claim of compliance effectively includes the resin.  Do not mix resins if you want an anchor which meets the BS.)  There are several other anchors on the market which also claim similar compliance.  Equipment Committee's current stance is to want to select an anchor with 959 following some additional tests to see how it behaves in a caving environment.  In particular, one fairly sensitive area relates to using resin in a caving environment.  Some resins are not capable of being used in the presence of water; so it is of little value to select an anchor with its specified resin which can't work in the damp conditions found in most caves.

Fourth, following a post on another thread (see Ship Badger on http://ukcaving.com/board/index.php/topic,3120.0/all.html#lastPost ), I am issuing an appeal for unused Eco Anchors, see general caving talk.

Sorry too much to do and too little time!

 

[Hughie]

I accept that I don't fully understand these things (obviously), but fail to see how these bolts are deemed "dangerous" if they take 3hrs of drilling and 4 battery packs to extricate, or are rendered to useless scrap when removed due to the agressiveness of removal.

To my agricultural mind, fixtures of this tenacity would seem pretty "bombproof".

Would I be right in thinking that the "failures" are more legislative/guideline induced, rather than being actually dangerous?

 

[graham]

Yes and No, Hughie. It took four hours and four battery packs to extricate that particular bolt because the attempt was made (uniquely for the UK so far) to remove the failed bolt along with the surrounding rock so that the complete assemblage might be studied.

It is true that no bolt has yet failed catastrophically under this scheme (unlike spits which have regularly stripped threads) but one of the reasons for that is that the scheme is taken seriously and every precaution is made to ensure that catastrophic failures do not occur.

 

[cap n chris]

.... e.g. a catastrophic failure of the 2nd bolt at Swildon's 20 would most likely result in an accident since people persist in clipping everything to a single anchor: people place their entire trust in it. On my most recent trips the idea was mooted to install a web-anchor-cam!

 

[Bob Mehew]

Some one has had the idea of PMing me.  As the answers should be seen by all, I am writing the answers to the PM in this post.
PM starts

Hi Bob.

Q1
If all the dodgy bolts (bar the standing proud ones until the commitee has made a decision on these) were removed, the cave would revert to its natural state, therefore surely "liability" would be transfered away from the body that installed them, and revert back to an individual cavers ability to cave safe.

Answer
No one can give an authoritative answer one way or the other as the facts do significantly matter in such a “legal case”.  My guess is no, since we have set a standard by placing an artificial anchor and are now hoisted on that standard.  Indeed, it seems to me that placing any artificial aide in a cave creates a duty to maintain it and replace it if it becomes unsafe for use.  My guess is that this duty also becomes even more onerous if the access controller has knowledge, so CCC Ltd is quite different from say a farmer. 

Also remember that the vast majority of Eco Anchors are placed to enable SRT, not to enable access by ladder and line.  So do we need SRT?  If we do, then I for one consider we have to abide by the legal implications that come with it. 

And for those who will no doubt be saying “it is up to me as to what risks to accept”; the simple answer is under the “Unfair Terms of Contract” law, you can’t.  That law does not allow you to sign away the rights of your dependants to sue some one, if they were liable for the accident which injured or killed you.  And that law dates back to around 1977 so don’t start on about recent “Nanny States”.  That point was brought home very expensively some decades ago to one club when they were sued, not by the injured party but by a relative.

End answer

Quote
The full statistics are

Pull test failures.  Rhino had 1 pull test fail (2nd time round) out of 16.  Hunters had 7 out of 16 pull test failures.  (I confirm there was an error in the previous posting about Hunters; I mistook one standing proud for a pull test failure.)  Swildons has 0 out of 3 pull test fails.  GB had 1 out of 4.  Thrupe had 1 out of 5.
Q2
Just to confirm...rhino now has no dodgy bolts yet remains closed....

Answer

I did not say Rhino has no other dodgy bolts.  The nature of the failure is unique and that makes me and others concerned about all the Eco Anchors in Rhino as well as the other caves mentioned (Hunters, GB, Swildon’s Cowsh Aven and Split Rock quarry) which have some common features with the Rhino anchors.  (Resin is not the only factor.)  But I don’t want to go into what those factors are at this time as they are still being sorted out.

End Answer

Q3
I hadnt realised there were so few bolts left, but had wondered .....even if the problem was due to environmental factors, this cannot be changed, how can the new bolt be scientifically more able to withstand environmental factors than the old bolt (unless one old/one new are paced side by side in HH for 10 years with periodic pull tests)

Therefore why not just change(or remove) the ones in thrupe,gb and rhino (3 in all???) leaving only one cave shut (hh) whilst the necessary investigations are done...


Answer

The factors involved in why the Rhino Eco Anchor failed its pull out test are still being investigated.  It is difficult to see why some 4,000 other Eco Anchors away from Mendip plus a few on Mendip are OK but at least one is not.  I do not believe the single failure undermines the quality of the Eco Anchor scheme.  Indeed the work done over the past month (yes only one month since this started!) has reinforced in many ways just how good the Eco Anchor is.  I therefore consider that replacing the suspect anchors would be acceptable.  The holding point has been the lack of Eco Anchors in our hands.

As you may have seen, I am appealing for unused Eco Anchors, having been alerted to the possible fact that a reasonable number exist out their.  I will accept criticism of not having the foresight of thinking some people outside of the Eco Anchor scheme might have reasonable numbers of anchors.  I will just plead guilty and offer no defence to that charge.  :-[  If we can get enough Eco Anchors, then Mendip can quickly replace all suspect anchors in Rhino, sort out Hunters according to the wishes of the land owner and do else where (after sufficient people have been trained in installing Eco Anchors).

End Answer

Lastly, if I & others involved in this problem start answering all PMs and E Mails sent to us, we will never be able to push this problem to a conclusion.  In addition, I am off on holiday on Thursday for a week and a bit.  (Whilst away I will be drafting the main report, so I am not doing nothing! But please don't tell my wife).  So don’t expect any more replies from me (or them).  Hopefully Equipment Committee’s meeting currently scheduled for 19 May (but yet to be confirmed) will be able to find a way through.  Could we have a moratorium on this topic until then?  No doubt it is frustrating to those of you on Mendip to have closed caves, it is also a frustration to those of us who are dealing with the problem, seeing so much written, some of which is pure rubbish.

Bob

PS If so many people want to go down Rhino as might be deduced from all the interest, perhaps we should place a limit on numbers per day so the cave is conserved?  Why not debate that conservation point in the mean time?  But please do it on under a new title.

 

[zomjon]

I'm a little perplexed by the continual impatient push by some people on this forum to have these few caves reopened for SRT, when I think this would be the perfect opportunity to get out and about to other caving areas and sample their 'little' SRT experiences.

 

[whitelackington]

We have patiently sat back for a month now.
There are very few s.r.t. caves on Mendip, so we greatly value what we have.
added to this Rhino rift is the main s.r.t. cave on mendip.
Added to this Rhino Rift right hand route is the only proper s.r.t.
cave on mendip where it is done on 8mm spits,
very important for fresh s.r.t.ers wishing to go abroad :-\

 

[Jopo]

Quote from Bob Mehew

Hopefully Equipment Committee’s meeting currently scheduled for 19 May (but yet to be confirmed) will be able to find a way through.  Could we have a moratorium on this topic until then?  

Bob.
I appreciate your desire for a moratorium but as you appear, quite rightly, to want to keep the debate open I hope you don't mind my comments instead of a pm. I have restrained myself from commenting so far but feel that I can contribute.

Failures of resin bonded anchors in caves may be exceedingly rare, (so far), but the problem has been seen in climbing circles.
Without willing to enter the debate about different uses/environments I would mention that the detrimental effect of the host rock, including limestone, upon SOME resins has been noted.
I am in contact with Serco Ryan and Fischer Fixings who replaced old spits and loose p hangers on Kinsley Crag for the Yorkshire Bolting forum, (the WBCRT is investigating the FZEA fixings - see the BCRC website soon), and have asked for information on the long term effect of limestone on resin. I will forward any info they may have. I have also asked their opinion on repeated test pulls on resin anchors, which could possibly weaken the bond.

I hope the BCA equipment committee will not restrict itself to seeking resin anchors as the only solution.

Before someone trots out the 'Why don't you get off your arse and get involved?' bit, it is well to remember that we cannot all be members of all committees all of the time. We all have limited time and some of us choose to put our efforts into other aspects of caving - but can still contribute to a sensible discussion electronically.

(It's called getting your retribution in first).

Fire away.

Jopo

 

[cap n chris]

We have patiently sat back for a month now.

It would be interesting to see what you're like when you're being impatient.

 

[Peter Burgess]

We have patiently sat back for a month now.

It would be interesting to see what you're like when you're being impatient.

What an interesting thought.

 

[wormster]

We have patiently sat back for a month now.

It would be interesting to see what you're like when you're being impatient.

What an interesting thought.

Nah the way i'm feeling at the moment:

reach for the ak47

 

[Bob Mehew]

Failures of resin bonded anchors in caves may be exceedingly rare, (so far), but the problem has been seen in climbing circles.
Without willing to enter the debate about different uses/environments I would mention that the detrimental effect of the host rock, including limestone, upon SOME resins has been noted.
I am in contact with Serco Ryan and Fischer Fixings who replaced old spits and loose p hangers on Kinsley Crag for the Yorkshire Bolting forum, (the WBCRT is investigating the FZEA fixings - see the BCRC website soon), and have asked for information on the long term effect of limestone on resin. I will forward any info they may have. I have also asked their opinion on repeated test pulls on resin anchors, which could possibly weaken the bond.

I hope the BCA equipment committee will not restrict itself to seeking resin anchors as the only solution.

Thank you Jopo for some informed comment and sensible queries.

Re resin / limestone interactions, it is worth noting that the failed anchor in Rhino pulled out of the resin rather than the resin out of the rock.  So I am unsure how such an interaction could affect this bond.  I would be most grateful for any information you acquire from your sources.  I would also be happy to travel to where ever to discuss our experiences with your contacts in due course after my holiday.

Resin anchors do have a number of advantages over other types of equivalent strength anchors; notably they don't permanently load the rock like expansion anchors and in practice, don't catastrophically fail but give a warning by cracked resin or coming some distance out of the hole.  They also were a cheaper option, though I have not recently checked that. 

 

[Peter Burgess]

Thank you Jopo for some informed comment and sensible queries.

That's what I thought too. 

 

[cap n chris]

Ah! ... the voice of reason returns.

 

[Jopo]

It is worth looking at the Fischer site and find the Zykon Hammerset anchor FZEA II which is a clever little expansion bolt that does not stress the rock. Indeed that is the main selling point. These are the anchors which the WBCRT has been drop testing.

I am in no way suggesting that this would be a replacement anchor for permanent anchors as they do require a plate and bolt but they are however available is s/s and I have developed a way in which they can be removed without damaging the host or the anchor.
What I really want to say is that there are alternatives.

Fischer have offered today to conduct trials with any of their large range of anchors, " We can arrange free of charge for an engineer to come to you and carry out whatever testing you require and discuss general information about fixings".
I am still chasing info on resin degradation by the host.

On a historical note. Many years ago Pete Cardy and me were involved with the beginnings of the bolting scheme. We felt that what was needed was a hole which was larger at the back than the front to secure the resin, (I will admit we were both not the biggest fans of resin anchors). We never did better than achieve a dumb-bell shaped hole and wrecked a few drill bits in the attempt.
What Fischer has done is to develop a drill which does just that - forms a cone into which the bolt expands leaving the rock stress free. Very clever.

Jopo

 

[Peter Burgess]

I was wondering how long it would be before someone suggested the Lewis pin as a possible solution that doesn't prestress the rock, cos that's very roughly the thing that Jopo is describing, in modern form.

 

[Hughie]

I was wondering how long it would be before someone suggested the Lewis pin as a possible solution that doesn't prestress the rock, cos that's very roughly the thing that Jopo is describing, in modern form.

You should have suggested it earlier, Peter. 

 

[Bob Mehew]

It is worth looking at the Fischer site and find the Zykon Hammerset anchor FZEA II which is a clever little expansion bolt that does not stress the rock. Indeed that is the main selling point. These are the anchors which the WBCRT has been drop testing.

Fischer have offered today to conduct trials with any of their large range of anchors, " We can arrange free of charge for an engineer to come to you and carry out whatever testing you require and discuss general information about fixings".
I am still chasing info on resin degradation by the host.

On a historical note. Many years ago Pete Cardy and me were involved with the beginnings of the bolting scheme. We felt that what was needed was a hole which was larger at the back than the front to secure the resin, (I will admit we were both not the biggest fans of resin anchors). We never did better than achieve a dumb-bell shaped hole and wrecked a few drill bits in the attempt.
What Fischer has done is to develop a drill which does just that - forms a cone into which the bolt expands leaving the rock stress free. Very clever.

Jopo

many thanks for alerting me to the FZEA II which I note only became available in January this year.  The ETA approval certificate notes their use to static or quasi static loadings.  I am also trying to work out the meaning of Table 5 & 7 which if I understand their notational system, implies relatively low failure strengths compared to the Eco Anchor.  But it is quite a neat design.  I must admit that the limited knowledge I had gained about undercutting holes was you needed a special jig to achieve it.  From their installation diagram, I got the impression that one just rotated the drill bit in the hole off axis to produce an undercut.  I presume they just wear out bearings in their drills or possibly the batteries get knackered before the bearings.  I can also appreciate in a rescue you want to place an anchor fast so can't wait around for resin to set.  I presume you have compared strengths to see which gives you the best strength for hole size.  Do you have a chart of such data?

We also have this problem with screw in bits left in caves.  For some reason, cavers seem to want to remove them, so it also seems to me that you are back to one of the weaknesses of the Spit. 

I would also be interested to hear as to how your drop tests have gone on including what you did and what you measured.  Who should I contact in WBCRT for the info?

 

[Jopo]

Bob

I am not pushing the FZEA as a p hanger replacement. I too have reservations as a hanger and bolt would be required.

The Fischer people are very helpful and I think use should be made of their technical knowledge.

I must admit that the limited knowledge I had gained about undercutting holes was you needed a special jig to achieve it.  From their installation diagram, I got the impression that one just rotated the drill bit in the hole off axis to produce an undercut.  I presume they just wear out bearings in their drills or possibly the batteries get knackered before the bearings.

Not true. The Fischer drill is very efficient and the final rotational movement of the drill, forming the cone, is very easy.
The drill bit has a positive depth stop and the back of the drill bit is shaped to prevent it cutting.

I would also be interested to hear as to how your drop tests have gone on including what you did and what you measured.  Who should I contact in WBCRT for the info?

Me or Vince Alkins.

Starting small we have dropped 80k at FF2 onto the FZEZ 12mm (Petzl 25kN twist and 8.8 M12x20 hex head) using 11mm SuperStatic and fig 8 knots. The fixings were then pull tested by the Fischer rep and achieved the spec load. We also took the opportunity to drop test a s/s 12mm through bolt - which is our stock rescue anchor - and the rope broke. We are satisfied that it worth doing further tests.
Next step is to up the load to 100k using chain to take out variables such as stretch and knot tightening - still using FF2.
We do not have access to a load cell (help?) to measure peak force but by using chain we can be reasonably sure that our calculations will be close.
Step 3 will be on vertical and horizontal fixings and we have in mind 200k (more realistic rescue load) starting at FF0.5 and working up.
As I mentioned in an earlier thread I am wary of static load tests when the worst case will be a shock load.

I am trying to find out, without success so far, if there is any technical info about the repeated test loading of resin anchors.
To my mind placing a heavy test load on a p hanger only tells you that the anchor has withstood that load - it does not tell you if you have induced a weakness.
Given the deformation of the steel under load, and the subsequent return when relaxed, I cannot see a simple way to measure any small movement in the shank/resin or resin/rock bond.
Any ideas?
If such a movement is present, which I suspect could well be the case, until it becomes clearly visible we have no way of knowing if the test regime is gradually weakening the bond. This may also explain why a p hanger that had previously passed tests suddenly 'fails'. Once the bond had been disturbed surely there would be a cumulative effect?

It has been mentioned that one of the 'failures' showed the shank had moved out of the resin and the unsuitability of the resin to bond in wet conditions was suggested as a possible cause. Perhaps test pulls should be considered another possibility.

I feel so strongly about testing being a possible cause of 'failure', (so probably deserve getting my bollocks chewed off), that I would ask that the BCA bolt guru's consider reducing test loads until the problem(s) are sorted.

So much for a moratorium eh Bob!

Enough for now - got stretchers to design.


Jopo

 

[Andy Sparrow]

This has just been issued:



Statement from the Equipment & Techniques Committee, concerning Rhino Rift

Following a report of loss of resin from an anchor in Rhino Rift, an investigation was put in hand by the Equipment Committee.

As a result, precautionary measures were taken where appropriate to restrict access to certain sites pending a full investigation of the problem.

As a result of this investigation the Equipment Committee have concluded that there is not a safety issue in the caves concerned.

The Equipment Committee have, however, identified some failings in the Eco Anchor program procedures and have agreed changes which are intended to prevent these problems re-occurring.

It was also agreed that the disadvantages of using a puller as part of routine testing outweigh the advantages and as a result the Equipment Committee no longer recommend that Eco Anchors be pulled as part of routine testing.

Andy Pryke
Chairman Equipment &Techniques Committee
British Caving Association 
19/05/07