Those that climb in the area and follow the likes of ukclimbing.com probably already know about this but...

www.thebmc.co.uk/bolt-failures-on-north-wales-limestone

incidentally, it also highlights anchors in general and the use of non-approved i.e. stuff thats not to EN959.

just 'coz something looks like a decent 8mm (or greater) bolt doesn't mean there is any guarantee of its strength and even more importantly if its not made to the defined standard there is a high chance of manufacturing defects i.e. cracks in cast stuff rather than forged stuff etc etc.

i have already red it - and was attempting to think of something constructive to say , i hope this gets a follow up and investigation

one potential problem that leaps out is : was this a permanent install ?

the article SEEMs to imply that these bolts were installed in 2011

i use these bolts all the time [ well actually i use excaliburs and hiltis ] - but not for permanent installs -

i thought that was the entire point of them [ for caver climber use ] , ie : a small drill hole [ i use 10mms ] , retreavable , reusable [ 3 ~ 5 times ] , once removed only a 10mm hole remains that can be smeared with mud / grit

thats why i love em - no great hassle - and if the pitch isnt a goer - you can abandon it - leaving no gear behind - and minilmal trace

as they are galv / plated [ different mffrs are different spec ] - they should not - at least by my understanding be left in as a permanent because :

1 - electrolytic action between the bolt and the SS hanger
2 - corrosion from water in the hole [ worse in mines etc where acidity is a bigger problem ]

while i am aware that they are not individualy tested - or approved - there :

www.excaliburscrewbolts.com/index.php?op...rticle&id=5&Itemid=6

is the specs for what i use

i have always been happi usuing them as various industries go through hundreds of boxes a week - and abuse the hell out of them - with no paterns of defect induced failure

so - hears hoping that the investigation turns up a definitive cause of failure -

because the prospect of random batch defects scares the shiite out of me

any one want to buy a mixed box of used / new screwbolts - lol

but last word - like i say - they are a temporary solution to exploring - not a permanent anchor tool - or at least thats my philosophy

If you are rigging correctly then a single bolt failure should not be an issue (except perhaps in the underwear department... )

LesW wrote:
No doubt true on the most part, but, what if all bolts on the route are from the same bad batches? Somthing worth being weary of.

Not so long ago we were happy (happy? Well we lived with it... ) to rig off of M8 Spits. These used to fail catastrophically for a pastime, so much so that modern rigging techniques evolved specifically to deal with anchor failures...
Failure of a spit was a rite of passage and generally resulted in nothing worse than a change of underwear

Now we have very good anchors in most caves and with the rapid turnover of cavers, most people don't even remember what a spit was. I'm not advocating that we go back to them (although they still have their place) but it is important we find out what happened with the Thunderbolt that failed before we write them off as unsuitable...

You make me laugh Tim its like when i got in your landy the first just coz it looks descent on the outside there,s no guarantee that the doors won,t drop off or the windows won,t fall out and finally if tim has not welded it to a high standard defects such as the floor falling through are possible hence wearing you seatbelt prevents plimsole burn and possible prevention of leg wrap around the rear axle,there is a moral to this story,do not trust anybodys car who goes on about safety bolts ,the fall from the bolt failure won,t happen but falling out of the door, going through the floor of a landy have a high falure rate and its not to EN959 But falls under ES999,,Micks just fell out of the door,is he alright says the emergancy service,tim says i don,t know i carnt see him on the road but we were going down the horse shoe pass ,there it is folks if the landy did,t kill him the fuc.in fall did, does that sound about right Tim.
Mick

lolololol mick you nutter - my landys sound as a pound...kind of! And its got new doors on now!

You know all about bailing out of vehicles anyway and don't make me laugh about seat belts coz you never wear them! You don't even need doors on a veichle for them to be safe anyway (according to the mot) but you do need to be strapped in.

I've still got plenty of m8 Spits

Andy - they were (and have been) used to bolt quite a few sports climbs in north wales - i.e. as permanent installations. The bolt was 'new' (i.e. corrosion was not an issue in the failure) and it wasn't even the top one that failed but rather it was a bolt at the bottom of the route which failed with minimum amount of side pull. If i was a guessing man i'd say it was a hairline crack from the casting/cooling process and it was always going to fail but the follow-up report will no doubt give us the facts.

Cast rather than forged scares the crap out of me for any application i'm hanging my life on. Which is why all proper anchors, biners etc etc are NOT cast!

tim - i havent got time to do a proper repply - but IMHO they are not cast - they ARE forged - i cannot speak for all generic " screwbolt " anchors - but i have a handfull of hiltis - that are A4 stainless [ reseved for special occasions ] - and they are forged

heck - just look at the shear strengrhs given

they where also resined in so there is a possible chemical reaction, if there was a hair line crack the resin would have got into it and made matters worse, just a thought