The reason EN959 requires higher test loads than EN795 is absolutely not as simplistic as Bob suggests and clearly demonstrates the major misunderstanding some appear to have on the subject.
Firstly, the maximum force allowable on a body/anchor in mountaineering is 12kN and the maximum force allowable on a body/anchor in industry is 6kN.
Because EN959 anchors are more likely to be used as running belays, the forces placed on them could easily be double that which could be applied if you just fell directly onto an anchor via, e.g. a cow's tail.
The more recent UIAA recommended increased axial test of 20kN may have something to do with longer life. You don't have to wait for this to be filtered into EN959, if it's thought to be important enough it should be implemented straight away. People were carrying out 12kN substrate tests (formally 10kN) for EN795 anchors a good few years before the standard was amended.
In reality, applying such large forces is most unlikely even in the sport of mountaineering and likely never in a typical caving application unless you were planning on doing a very slow vertical aid climb with resin anchors. For these considerably more dangerous activities we are more likely to use an 8mm HKD or through-bolt!!!!
Anchors used in caves are much more akin to the industrial rope access application where they are being used for full suspension, as opposed to mountaineering, where they are designed primarily for taking leader falls and probably goes a long way to explaining why so many anchors are now being reported loose.
Just because EN795 is an industrial standard and we are all cavers doesn't mean it shouldn't be considered, far from it.
The more professional approach to this would have been to look at both standards together. If there are particular elements of EN795 that it is considered provide a greater level of safety than EN959, e.g. testing, then they should be adopted and vice versa, e.g. higher substrate strength and rotational tests. This would probably be considered the best way to cover any arses, rather than the very blinkered thinking which seems to have been applied.
Petzl took a similar approach when they first produced the Ecrin Best helmet. The shell of the helmet conformed to the industrial building site helmet standard and the chin strap buckle conformed to the mountaineering standard. With the chin strap fastened it conformed to EN12492 and when you unfastened the chin strap it conformed to EN397.
I don?t know about your ?5% Fractile Limit? but the reference to SWL and 10kN confuse me as well. Here's the link:
http://british-caving.org.uk/wiki3/doku.php?id=equipment_techniques:summary_of_test_data
As Bob mentions in his post, there is a move to stop using the term SWL and instead use WLL, however a complete changeover in the workplace is not likely to come in for some years. The WLL takes into account the particular service conditions or configurations the item of equipment may be used in.
The term SWL does have an impact on industrial rope access activities. When the Lifting Operations & Lifting Equipment Regulations came into force in 1998 the term ?Load? was applied to people. If the majority of a person?s weight is supported mainly by the harness then this is considered to be a ?lifting operation?. All the items of equipment in the suspension chain are then deemed as being ?lifting equipment? and as such ?should? be marked with a SWL.
In reality, hardly any of the equipment used in the rope access industry has a SWL marked on it. In response to the anomaly, IRATA produced a document to explain how the regulations applied to rope based access systems. The document is currently withdrawn whilst undergoing a review by the HSE but here?s a copy of it:
http://www.irata.org/pdf_word/HSE%20LOLER%202007.pdf
Bob uses most of his earlier post to emphasise the fundamental differences between the different standards but I think this is very muddled thinking and completely the wrong approach.
The issue relating to EN959 and the substrate testing of only one anchor being against standard engineering practice sounds to me as though there is some reluctance to test more samples than the standard states. If you feel it needs more samples tested then test some more samples. Simples.
If I'm reading Bob?s post correctly, it took nearly 7 years to work out that axially testing the BP anchors to the agreed 6kN, damaged, or at least gave the impression of damaging the fixing. Surely this fact should have been identified a little sooner, like before they were chosen as the 'most appropriate' anchor.
It was obviously considered important in the early 2000's that testing should be carried out or the BCA wouldn't have spent thousands of its members ?'s on test rigs but then in 2007 everything changes. Routine examinations in the Dales that were originally deemed so important are scrapped because it was too hard to find people to do them and half the country stop doing axial tests after installation. I only discovered this from reading the CNCC anchor thread only the other day. I don?t go to the Dales much.
Bob Mehew explains, ?
The original NCA / BCA scheme required an ongoing inspection program. The volunteer resources required for this became overwhelming so that around 2007 this was dropped in line with EN959.?
EN959 is a minimum performance standard for mountaineering rock anchors, not a detailed installation, testing and ongoing inspection program, which is what the BCA anchor scheme is supposed to be. To ?
drop in line with EN959?, clearly demonstrates the major misunderstanding people have on the subject and, in my mind, effectively abandons the original principals of the BCA anchor scheme.
Derbyshire may well have to live with its decision to continue in-situ testing, which I believe everybody should at least be doing, but it is those who have chosen not to test who will have the biggest burden, when one of them pops out and somebody has to try and explain to a judge why it wasn't considered important to do any more testing of anchors despite all the other regions having a diametrically opposing view.
In the ?Rigging with Eco Anchors? section of the website, BCA say,
?
Due to the shape of the Eco anchor, more than one rope can be rigged from each anchor point. This practice may lead to some tangling of the ropes, but this is far safer than using other (non Eco) anchor points, where security and strength of placement cannot be guaranteed.?
If official BCA anchors are not tested at least after installation then they absolutely cannot be guaranteed as providing security and strength of placement.
It?s clear, from the increasing number of loose anchors being reported around the country, that at some point in the not too distant future, BP anchors may well have to be removed and replaced.
Bob says, ?
Although BP claim their anchors can be drilled out, the testing experience does indicate the potential for loss of 'location' and a conservation issue. We have started work to confirm an extraction process which does not loose location.?
This is what BP actually say about it:
http://www.bolt-products.com/SustainableBolting.htm
As with the issues of axial testing, surely the poor conservation credentials of the extraction process of BP anchor should have been identified before they were chosen as the ?most appropriate? anchor, and not only just being considered now.
It amazes me that those who constantly bang on about cave conservation in the south haven?t had something to say about this ?conservation dilemma.?
On the issue of chloride stress corrosion cracking, the 2007 BMC report stated that no anchor on a UK sea cliff had failed due to it.
10 years on, have there been any reports of any failures due to it?
DEFRA suggested that there was no evidence from their sampling program for Yorkshire that chloride levels existed at levels which might cause concern when compared to the 200ppm threshold value for using 304 stainless steel if no significant human activity is near by. Do they still hold this view?
The British Stainless Steel Association in 2013 said,
?
In the water treatment industry, taking account of all relevant factors grade 304 is regarded as being suitable for up to 200 ppm chloride. 316 is OK for 100 to 1000 ppm. The levels you are talking about for caving systems are massively below this limit. In addition, the low temperatures found in caves are another positive factor. Overall, the risk of corrosion failure of 316 anchors in these conditions is practically nil.?
Unfortunately, they don?t say what the overall risk of corrosion failure of 304 anchors in these conditions is. 4 years on, do they have any further comment?
I know very little about the subject, but (as they say) I know a man that does. I used to sit on the IRATA Health & Safety Committee with Dr. Chris Robins, a former UK Principal Inspector for the HSE Offshore Division, who, if I?m not mistaken, is an authority on SCC. He gave a lecture on the subject at a Lyon Equipment Technical Symposium a few years ago. I couldn?t access the HSE report mentioned on the report Bob linked to, but I wouldn?t be surprised if he didn?t write it.
I would be more than happy to ask him for his opinion about using 304 anchors in caves and in addition, benefit from his opinion from a health and safety perspective.
The BCA E&T minutes on the subject make ?interesting? reading.
Did anybody consider asking Mark Salmon of the Construction Fixings Association for his opinion. He really is an authority on anchors, being the principal author of the EN795 standard. I briefly sat on the BSEN7883, Code of practice for the design, selection, installation, use and maintenance of anchor devices conforming to BSEN795, committee with him when we were reviewing the issues relating to permanent rooftop anchors for rope access purposes.
Again, I would be more than happy to ask him for his opinions.
I am in no way trying to flog a load of Petzl gear but Bob says, ?
The costs differences between BP and Collinox are substantial. In round terms and including resin costs, we believe we spend about ?7 per BP anchor compared to ?15 for the Collinox. We have not considered seeking a quote or a large batch of Collinox anchors.?
If someone had sought a quote for Collinox anchors I?m sure they could be purchased for about ?10.00 (Inc. resin & Vat) which, when compared with ?7.00 for the BP is pretty good when you consider the far superior manufacturing process and resulting robustness, smaller hole, ease of testing and inspection and ease of removal. The 304/316 debate would obviously need resolving before they could even be considered.
The whole scheme needs a comprehensive review because it?s clear just from some of the posts on this and other threads that none of us are doing what we say we are doing. Most EN standards and Codes of Practice are reviewed every 5 years, so it?s long overdue.
I would be more than happy to be involved in that process.
Mark
