Near Miss: Anchor bolt failure incident report.

20 kN wrote:Glad you're okay. I am not overly surprised the bolt pulled as that rock looks like crap as do the placements. Why dident the developer place the bolts in the much-more-contiguous rock only 3' lower? I dont see any cracks there, making it far more idea. That would probably be a better option when the route gets rebolted.

Don't know the exact story behind this, but my guess is that the developer was trying to maximize the amount of climbing available on this extremely short piece of rock. Putting the anchors 3 feet lower would significantly shorten the two routes that end at this anchor on a percentage basis. You are right that the rock they are placed in is choss, and the rock a few feet lower is much higher quality.

kennoyce wrote: Don't know the exact story behind this, but my guess is that the developer was trying to maximize the amount of climbing available on this extremely short piece of rock. Putting the anchors 3 feet lower would significantly shorten the two routes that end at this anchor on a percentage basis. You are right that the rock they are placed in is choss, and the rock a few feet lower is much higher quality.

If chopping 3' off the route means "significantly shoring it" then it sounds more like a bolted boulder problem. Maybe it should be converted to a boulder problem in that case? I dont know, I am not there, but it's worth considering. As the story goes, not everything that can be climbed should. Developers cannot put route length above safety. The main priority of a developer always needs to be ensuring the bolt placements s/he places are absolutely as strong as possible, and if it's just not possible to get solid bolt placements in then one should probably just develop elsewhere.

Thankfully you two made it out alive. Tell that boy no more victory whips. We got climbing to do!

20 kN wrote: If chopping 3' off the route means "significantly shoring it" then it sounds more like a bolted boulder problem. Maybe it should be converted to a boulder problem in that case? I dont know, I am not there, but it's worth considering.

Honestly it would be a boulder problem if there was a decent landing.

I tend to like the softer Rock and crags that don't look good at first or second glance. Often the choss is where the good climbing is.

I recently experienced the uncleanable hole syndrome when placing a big mechanical anchor.
The hilti hit tz glue in threaded rod anchors below are designed to work in uncleared holes. They don't come in stainless though. Anyone have experience with them? The spec 3" version is actually like 6" long with 3" of threads. So they are plenty long for our purposes.

buildsite.com/pdf/hilti/HIT…

Possibly the Hilti US website is a bit out of date or at least the bit you linked to.
The HIT-TZ is different to the one you linked, it is the version for use with a capsule system and IS NOT for uncleaned holes, it also comes in 316SS which is then the TZR.
The one you showed is now called HIT-Z and also comes in 316 when it is the HIT-Z-R and is for uncleaned holes. Note it is only to be used in this application with HIT HY200A resin which is a Urethane Methyacrylate, it is not for use with RE500.
It´s still better to try to clean the hole as well as possible even with this system, as I said above washing will give stronger results.

Thanks Jim. You are a wealth of knowledge.

FYI the anchors on Banana Dance have been replaced. It was not glue failure but rock quality failure instead. The new anchor is expansion bolts.

What do people feel about simple pull proof testing (i.e. yank on suspect bolts to 2000 lbs) at the crag? Maybe an idea that has not caught on yet but is a standard for climbing gym design? This approach could give a sh!t about install practices and only cares about repeatable end results...

It's not a bad idea. With mechanical bolts you can use a torque wrench to test by tightening suspect anchors to the manufacturer's recomended torque. If it clicks out the placement is probably good.

Fleetwood Matt wrote:What do people feel about simple pull proof testing (i.e. yank on suspect bolts to 2000 lbs) at the crag? Maybe an idea that has not caught on yet but is a standard for climbing gym design? This approach could give a sh!t about install practices and only cares about repeatable end results...

As C.Williams said above, with mechanical bolts, as long as it torques to spec it's good to go. If it won't reach the specified torque you know you have problems. As far as glue-ins go, yeah, a pull test could be a good idea, however, making a pull test set-up that will work easily without damaging the rock could be pretty tricky.

kennoyce wrote: As C.Williams said above, with mechanical bolts, as long as it torques to spec it's good to go. If it won't reach the specified torque you know you have problems. As far as glue-ins go, yeah, a pull test could be a good idea, however, making a pull test set-up that will work easily without damaging the rock could be pretty tricky.

The best thing to do at a site where there isn't a lot of knowledge about strength of bolts is to do testing.
And I mean knowledge gained by actual bolts installed and used for years.

Or if you are installing something new, even using a new glue.

You should use rock near the ground, where it's easy to test. And even pull to destruction, to get real numbers. And do enough tests to get a reasonable idea of how things vary. That means on the order of ten tests: just a couple is not enough.

And yes, a pullout test is NOT testing the anchor in the direction that a falling load puts on it. But in general, an anchor that is strong enough in axial (straight out) load is likely going to be also strong enough in radial load.

And as the cliff becomes more inclined, you DO load it more axially.

In any event, as long as you buy an anchor that has a CE mark (passes EN 959) or a UIAA safety label, then the anchor itself has already been tested. It's strong enough. What YOU need to test is how it interacts with the rock.

That assumes you buy certified anchors.

But why not? Would you put tires on your car that nobody tested according to a standard??? Or brakes? Or use a rope that isn't certified?

The idea is you are bolting for a long time, and for something where a failure could hurt or kill someone.

You cannot rely on the end torque of an expansion anchor: that doesn't tell you enough. It just means the anchor is torqued enough, not if the rock all fail.

You also to use that grey matter on the top of your shoulders: THINK.
There have been some failures in the UK on slate cliffs for example: the anchors seemed strong initially, but slate is special, is laid down in sheets. An expansion anchor is not the best anchor for it. And in fact SOME parts of the cliff might behave VERY differently from others because of how the rock sheets are oriented.

You can rent or borrow hydraulic bolt testers. Even make one.
Sure it's going to be a hassle, but then so is going to visit in hospital someone who fell off a badly bolted route.

Alan Jarvis
UIAA

WarthogARJ wrote: You cannot rely on the end torque of an expansion anchor: that doesn't tell you enough. It just means the anchor is torqued enough, not if the rock all fail.

Sorry, but this simply isn't true. Torqueing a bolt to spec is axially testing the bolt to the amount that the manufacturer of the bolt has determined to be a sufficient test. On most mechanical bolts the bolt will hold the same amount regardless of whether it's torqued or not, you could hammer the bolt into the hole, finger tighten the nut onto a hanger, and in the end it would have the same strength as a bolt that is torqued to spec. The reason for the torque spec is to test the placement of the bolt and ensure that it will hold.

misty murphy wrote:FYI the anchors on Banana Dance have been replaced. It was not glue failure but rock quality failure instead. The new anchor is expansion bolts.

Thanks Misty, I think we all owe you and Bill a drink for the work you guys have put in!

In any event, as long as you buy an anchor that has a CE mark (passes EN 959) or a UIAA safety label, then the anchor itself has already been tested.........
You cannot rely on the end torque of an expansion anchor: that doesn't tell you enough. It just means the anchor is torqued enough, not if the rock all fail.

It is illegal to put the CE mark on a rock anchor for sold for climbing purposes, YOU should know that.

Wedge bolts are torque-controlled anchors, if they achieve the specified torqued then they are tested to the appropriate pull-out value, for the normal 24Nm on a 10mm bolt this is around 14kN. With other types of bolt this may not apply.

Jim Titt wrote:Wedge bolts are torque-controlled anchors, if they achieve the specified torqued then they are tested to the appropriate pull-out value, for the normal 24Nm on a 10mm bolt this is around 14kN. With other types of bolt this may not apply.

Thanks Jim, That's what I was trying to say above, you just did a much better job of it;)

Fleetwood Matt wrote:What do people feel about simple pull proof testing (i.e. yank on suspect bolts to 2000 lbs) at the crag? Maybe an idea that has not caught on yet but is a standard for climbing gym design? This approach could give a sh!t about install practices and only cares about repeatable end results...

I suggest that we ask climbing friend Aleks to pull on the bolt with his meaty mitts. He could achieve the requisite 8.9kN test required by science (2000 lbs for us imperialists) Do it for science climbing friend.

Matt Stroebel wrote: I suggest that we ask climbing friend Aleks to pull on the bolt with his meaty mitts. He could achieve the requisite 8.9kN test required by science (2000 lbs for us imperialists) Do it for science climbing friend.

climbing friend, excellent idea most you have! although I may want to save my crushing grip strength for the bold flash rather than fiddling with your beloved bolts.

I am quite disturb by the foul weather and lack of bold flash lately. Do you have any suggestion for winter activity as I am now doing the living in a place of western colorado with only mediocre small boulder gym of climbing rocks? I would perhaps hangboard more but feel I do not have enough sexual frustration pent up as required nor am i quite nerd enough to follow a disciplined plan with overly complex schedules and cycles, whether macro or micro periodized, or unified mezocycle.

Just found this thread and thought I'd toss my 2-cents in.

The rock is red-colored. The glue is grey. Looking at the photo, it's clear that the glue (if that what it is) did not bond to the rock, but for a small area right near the eye.

It's impossible to tell from the photo but I have a couple theories.

1) That's not a glue (adhesive) but a binding mortar, inappropriate for soft rock.

2) The glue hardened in the nozzle too much before being (forcefully) injected into the hole. Only the glue near the eye, the last out of the nozzle, was still liquid enough to actually bond. (It looks like Powers AC-100, which hardens annoyingly fast.)

I use ACA 100 Gold a lot. It does harden fast. and it does seem to have not bonded with the rock at all. I would use a slower curing glue( Hilti RE-500 is one) for a ribbed bolt like that, versus the Wave-bolts I use. I also don't know if expansion bolts are a better option for the replacement. However the position is far better so i feel that its a non-issue.