Pros and Cons of Different Bolts

[hrock]

ok the pros and cons of different bolts

expansions: very quick to fit and can be used at once, work well in good rock, but can not be removed if bolt replacement is needed

p bolt and the new slimier spec bolts: time consuming to fit ans can not be used striate away, will cope ith sightly weaker rock as dose not pre stress it and spreads the load along the hole length better.

but the most important fetcher is when the bolt is worn or not considered to be good it can be replace down the same hole so the good bolt placements can be used for ever rather than having to relocate them every 10-100 years

so the bolts in question at the top my main issue is that i dont think fixed rigging should pander too bigging easy at the expense of safety (why add a rub point when before there was non and that rope had been in for about 10 years.)

the lower bolt on the short climb.

i have never knowingly let any one abseil or prosec up it as it was.

on seeing the changes from the bottom (free hanging rope from bolt) i prosec ed up it to give it a test haviging seen the bolt i will not do it again. also i have never been on a trip with people waiting there they just climb up and stand around at the bottom of the big pitch so i was unaware of this problem.

my understanding of p bolting is that they are happy to put them in peak  but they have almost never been proposed (where they have, they have got agreement, but there were no bolts till a fue weeks back)  now the dca will not take responsibility for anything hung off a p bolt so from there on it would be down to the peak fund.

doing future bolting in this way will not only save the good bolt placements for future generations of cavers but would saver the peak fund/tsg a lot of money (?2.50 a bolt) as the dca would then be paying.


[gmod]This was originally in the "fixed rigging spesificly calcite aven, peak caven" thread in the Derbyshire Section. I've split off the messages relating to Bolts and Bolting in general and moved them to here in the Equipment Section and update the Subject.[/gmod]

 

[adep]

Henry,
As you more or less state, there are pro's and con's for both type of bolt, but i disagree about the argument about replacement, to drill out a resin anchor for replacemnt will result in a much alrge hole being created and therfore more resin will be required to glue the bolt in, i have never removed a resin anchor in this way, but would imagine it would be a real bitch to do, then you are hanging on a bolt in a hole which is now much larger than the bolt packed out with resin, not sure i like the idea of that, at least with an expansion bolt if it is used in conjunction with a Stainless maillion the mallion can be replaced or simply replace the hanger and leave the bolt in place if either become worn.

As you say though, the rub point is a concern but as someone else has pointed out, when being used the tendancy will be for the rope to be pulled away from the rock at the rub point anyway, the ropes that have just been replaced were installed by myself 5 years ago.

As for the single bolt i placed lower down above the first pitch, again i dont agree, its better and safer as it now is, and is bound to speed things up with a larger group

Judging from some of the replies on this forum, people seem to be in angreement mostly that it is an improvement now over what it was before, that perhaps needs some adjustment or further consideration to make a few improvements.

 

[martinm]

i would have thought here was a case for using expansion bolts

All good points above, but if you want a replaceable anchor that importantly doesn't stress the surrounding rock, consider these:-

http://www.essentialsupplies.co.uk/acatalog/Online_Catalogue_Excalibur_Eyebolts_76.html

The M12's are very strong and resistant to corrosion (Yellow passivated). See here for more info.

http://excaliburscrewbolts.com/index.php?option=com_content&view=article&id=36:eyb-12mm&catid=11:eyebolt&Itemid=39

I use them all the time in the Manifold area (no P bolts there for some reason  ) and you can unscrew them with a good sized bar and replace them at any time with the same bar. 

Regards, Mel.

 

[hrock]

the above screw in bolt will swap out a fue times but i think in time they would become too slack and a new hole would be required.

re the replacement of a p bolt you have to take the right kit with you but it is not hard to to just drill down each side of the bolt and then twist it with a long bar though the p once spinning pull out with a test rig or slimier. then stick a drill down the hole to clean it out remove all dust and resin in a new one.  if you had to make the hole bigger (not that you do) the bolt actualy gets stronger as the resin is stronger than the rock and you are spreading the load over more rock.

to propose a p bolt site you just have to put it forward to the dca. then they find a bolter (like sam) and give them the drill bolts and resin. if you have preposed them or even if not i am shore they would love a hand carrying kit and plassing the bolts.

i think the risen people steel mallions on p bolts is they think they are forgotten or abandoned if it is stiff they just think thats why it was left and keep trying.  people need educating that not using a mallion in pull though will were the bolts out . 

 

[SamT]

Some back ground reading here for folks (and you should really know the background/history/test methods and results to the P bolting scheme before passing opinion or comment on here.  :ang: )

Lots of stuff linked from here.... http://british-caving.org.uk/?page=108

Ade - I cant understand why you think using expansion bolts makes them any easier to replace.  As henry has stated, they cone stress the rock for a distance around the placement, using up valuable areas of rock for further placements.

How would you propose to remove/replace  a 12mm through  bolt without completely fucking the rock up around it. 

Henry - with regards to removing P bolts.  You are correct in as far as your described technique (i.e. drilling through the resin, down the side of the bolt, will work on old DMM eco anchors, but probably not on the new Bolt Products ones which will be placed in future as the 'twisted' metal of the BP ones fills the holes up with metal and will be very difficult to drill through.

The main point though, is that given the result of the testing done over the last few years, it is doubtful that any P bolt should 'ever' need replacing. (Clearly that cant be 100% true).  Even 'loose' bolts where the resin/rock interface has failed (thus the p bolt can be seen to twist slightly), when pull tested, proved to be ridiculously strong, requiring something like 15kN to extract ... 15kN!!!!!

of the 5000 or so P bolts placed so far, hundreds have been pull tested after nearly 20 years with no failures, to the extents that BCA/DCA/CNCC have agreed there is no need for further random pull tests on 'live' placements. instead, moving over to a system of pull testing a few placements in a couple of test beds dotted around the country.

The only issue is rope wear. 

Being made from 316 stainless steel there should be very little wear even on anchors placed on popular pull through routes. Anchors placed in Swinstow Hole Yorkshire, show very little signs of wear on their inner curvatures.

It seems that pull through routes should be ok, provided that the rope is not pulled through under load.  The issues in the Crabwalk in Giants were caused by instructors regularly 'lowering' lots of clients down so the rope is under load as it runs through the bolt.  This was solved by having a steel ring on a steel strop y hang, directly swaged through the P bolts (eliminating the need for mallions).

Anyway, got to dash. I'm sure this thread will continue.

 

[Ralph]

The major issue with 18mm P bolts is the amount of rock required to be removed is considerably more than with a 12mm bolt such as Petzl Colinox, Raumer, Fixe (and the Fixe is/was considerably stronger). Nor a problem when when adding/replacing the odd bolt but I remember doing the initial bolting on Long Rake and others such as Maskhill etc. A very tedious job requiring many visits).
P hangers have been problem to remove in the past even when they are loose, the main problem is the number of masonry drills that gets damaged in the process.(I've done several)
According the the Petzl rep (and I've never tried this myself) a Colinox can be screwed out with a crow bar. There MAY be situations in tight rifts or in placements close to or in the roof where this is difficult or impossible but it does seem to be a solution to both the ease and speed of placement and the ease of removal. However I guess we've now reinvented the wheel so there's no point in reinventing another? Time will tell and I for one won't be around.

Interestingly there is a thread in the Yorkshire section on the difficulty of removing perfectly good compression anchors with the intention of replacing them with resin anchors. Why bother if they so difficult to remove (is this political?). "If something ain't broke why fix it"

 

[SamT]

In reply to ralph.

The now BCA 'sanctioned' Bolt Products glue ins require a 16mm hole - not 18 and DCA has a 36v li-ion Hilti with hilti star bits for use, so its no big deal to make the small extra effort that results in a much better placements.

Also - plate hangers (couer etc) dont half knacker up your crabs which in turn can knacker up your ropes - see recent death in the climbing world.

 

[al]

Also - plate hangers (couer etc) dont half knacker up your crabs which in turn can knacker up your ropes - see recent death in the climbing world.

That's interesting, Sam - first I've heard of this. Certainly can't find any evidence on any of my gear, and my krabs and maillons have been in contact with plenty of coeurs over the past few years.

 

[Cave_Troll]

personally i had no problems removing the PBolt.
I suspect you're going to get variable results due to the quality of the original hole. If it was drilled wonky then its going to be really hard to get it out.

 

[SamT]

applies more to climbing falls - where the rope runs over the crab for a distance under load, the small nicks the crab caused by plate hangers can cut through the sheath or worse.  Climbers now tend to use one colour krab for the bolt end and one colour for the rope end, as to try and avoid any problems.

Its a much smaller effect/risk for cavers, however, we all use just one crab for both bolt and rope.

Still, I think it can be said that other than ease installation and removal.  P bolts are a far superior solution than through bolts/plate hangers and should, in general, be the first choice for permanent placements on popular routes.  (ignoring all aspects of exploratory caving etc).

 

[al]

Thanks Sam - I was interested because DCRO do need to use plate hangers if we have to place bolts (well, until they invent some really quick-setting resin!!) and if there is a problem with any of them, we'd like to know.

But I think the nicks you refer to must also be the result of falls because, like I say, I can't find any evidence (nicks, roughness etc) from general cave rigging. Worth bearing in mind though - I'll keep checking.

 

[SamT]

cows tail crabs are more prone, as they are more heavily loaded at times.  Not really a problem in caving terms, but worth being aware of.

 

[adep]

Sam,

I wasnt saying  expansion bolts are easier to replace because they certainly arent, in fact as you say they are probably impossible to get out cleanly, this certainly is where P bolts are better, all i am saying is expansion bolts are quicker to place and with the right approach ie using a maillion to prevent wear should not need replaceing but if need be the hanger can be replaced if nessasary, you also have the ability to tighten them up if they are loose something you cannot do with resin fix, and as for expansion bolts stressing the rock i think this minimal as long as they are not over tightned, does it matter anyway if the rock is sound.

We could debate the pro's and con's of the two type of fixings all day long, a lot of it is down to personal preferance

 

[Ralph]

I didn't suggest "coeur hangers on goujons" I suggest that according to Petzl Colinox (10mm) can be removed by "unscrewing" using a crow bar which should be easier than trying to remove a P bolt or compression anchor.  The hole can then be drilled out to it's original size and a new colinox fixed in place with a new batch of resin. I suppose with a bit of effort the old colinox could be cleaned and reused?
The type of repair would depend on what has broken down the metal to resin bond or the resin to rock bond.
I must confess I haven't see the new design of P bolt, maybe someone could post a photo here?

 

[Glenn]

 

[Cave_Troll]

We found that when we were hanging 200Kg loads off some steel plate anchors and using alloy crabs on a Hightec Quadra (a kind of stop with steel side plates), we were getting small nicks and burs as the square section steel bit into the ali alloy crab

 

[al]

We found that when we were hanging 200Kg loads off some steel plate anchors and using alloy crabs on a Heightec Quadra (a kind of stop with steel side plates), we were getting small nicks and burs as the square section steel bit into the ali alloy crab

It would never have happened with a Petzl ID :ras:

(Whoops - Paul will be shifting this to a "The Pros and Cons of ridiculously complicated rescue devices" thread next!!)

 

[adep]

If thats the new  "P Bolt", what size hole does it need drilling to fit it??

 

[Glenn]

If thats the new  "P Bolt", what size hole does it need drilling to fit it??

16mm

 

[cavermark]

We found that when we were hanging 200Kg loads off some steel plate anchors and using alloy crabs on a Hightec Quadra (a kind of stop with steel side plates), we were getting small nicks and burs as the square section steel bit into the ali alloy crab

Use a steel krab (a few grams can hardly matter in that scenario). I'll donate some free steel SG's if you need.