bolts and hangers on new routes

[*Chris*]

Is there any chance that the rope that was placed through the directional somehow ran across the nut and that is what spun the nut off? I find it hard to believe that just the weighting and unweighting would unscrew a nut the number of turns it would take to have it come off...especially since it was just led that day and I'm assuming the nut was not only hanging on by one or two threads. It would take what...6 or 8 full rotations of that nut to have it come off.

I find that unlikely given the orientation of the bolt in question relative to the one immediately above it. I find it much more likely that it was already quite loose when the leader clipped it and that this simply wasn't noticed at the time since the climb is fairly strenuous. At least I certainly felt it was strenuous.

[Adam]

it *could* have been loose... but when i clipped a draw through it the hanger didn't move, so either it was still solid or it just happened to snag on the rock just right as to not move.

i am inclined to believe it was snug when i clipped it but that just the clipping and then subsequent rope movement started wiggling it enough to start unscrewing during the toproping.

i'm sure it wasn't the rope rubbing against the nut as once you see the direction of the rope and how it tugs on the bolt it becomes pretty plausible.

[Murph]

This incident is something to think about, makes you wonder if bolts like these should be more common. Doubt it at $10 each…

http://www.mec.ca/Products/product_detail.jsp?PRODUCT%3C%3Eprd_id=845524442619296&FOLDER%3C%3Efolder_id=2534374302691197&bmUID=1210882227079

[mike]

For new hanger installations:
A good option would be to use double nuts. Put the first nut on, after the washer, then put on another nut... use two wrenches and apply oposing force simultanously to both nuts to lock them together. The face of one of the wrenches (unless you've got thin ones) will need to be ground down a bit to get it on to the inner nut. This will greatly reduce any chance of the anchor failing due to spinning of the hanger, breaking of crystals and/or movement of the pin itself caused by environmental factors such as temperature changes and freezing.
Put the nuts, washer and hanger on the pin before pounding it into the hole- this will let you beat up the end of the pin while hammering without rendering the pin useless. Mushrooming the pin head will provide added security to the anchor. This practice of putting everything together before applying the hammer will also aid in setting the pin to the proper depth.
A minimum of 3 threads beyond the last nut is, in most senarios, a good guideline to follow.

Mike

[STeveA]

The other choice is to cover the bolt in epoxy. This helps to keep water out of the bolt hole and prevent the nut from moving. We used to do that for anchor bolts at the top of Bald Peak since they are flat rather than vertical.

[Fred]

[STeveA]

I see your and add a

[chossmonkey]

I think having two nuts rather than one would be more of a safety issue than just having one properly tightened nut. As it is with stud bolts the biner can get flipped and hung up on the bolt. Having it stick out that much further would make it worse. Also it would do nothing to keep the hanger from spinning if the spinning is caused by an under torqued bolt or crystals being smashed under the hanger.


The thought of beating on the stud enough to mushroom it kinda seams like a bad idea too. I'm no metallurgists, but it seems like that could weaken the bolt.

One thing I have heard of that may or may not be safe is to get welding rod of whatever type the bolt is made from and make a small nub on the end of the bolt to keep the hanger and nut from being taken off after assembly. It would work similar to mushrooming the head. The heat could compromise the bolt as well though.


As to sealing holes, it can do more harm than good. If water getting into the hole really is a big issue due to where the bolts need to be placed, glue-in bolts would likely work much better. Its generally been accepted that water getting into the holes and causing damage is a myth. Sealing with epoxy would likely work better than silicone, but if it isn't sealed perfectly and water can get in the hole will be worse off since it won't be able to dry out as well as if it hadn't been partially sealed. Porous rock should never be sealed as water can come from the rock into the hole and be trapped until the rock dries out.

[mike]

Spinning hangers wouldn't matter- the bolts are tightened to each other, rather than compressing the hanger to the rock.
As for mushrooming the heads weakening the steel... maybe a little- certainly not very much. Welding of mushrooms could be done with 1/16" 316L rods... just a small tack- enough to stop the threads from functioning would be fine. Busting up the threads with a sharp blow from a chisel, before installation, would do the same trick too- if the nuts can't turn themselves off the pins then the hangers can't get off the pins either.

I figure that the nut which caused this entire thread was spun off by rope drag... after it was loostened by some mysterious force. The outside diameter of the nut is around 1cm (3.14D=circumference) so the circumference of the nut is ~3mm- that means that the total amount of rope required to spin a nut off of say 10 full threads is only 31.416cm... or in laymens terms 1 foot.

The key, in my mind, to good anchors is not torque value- due to the environment, impact forces applied, and just the nature of the beast- things change. Torque values get things correct in the first place- but can quickly be thrown out of wack.

The key to good anchors is keeping the nuts on the pins, and keeping the everything fairly snug and tight.

on another note, I think if the anchor that MEC is now selling, which Murph mentioned, had a KBII type anchor system rather than it's current pound-in-to-set arrangement, with something like an 8cm long pin, that it would be cat's ass.

Mike

[Murph]

Why not use a product like Loctite?? It would be a lot easier than pounding/ mushrooming heads or lugging a welder to the crag

http://www.loctiteproducts.com/products/detail.asp?catid=10&subid=48&plid=153

Locks threaded fasteners against vibration loosening
Ideal for nut and bolt applications 1/4" to 3/4" (6mm to 20mm)
Prevents threads from rusting and leaking
Removable with hand tools for easy disassembly
Temperature range: -65 degrees to 300 degrees Fahrenheit (-54 degrees to 149 degrees Celsius)

[mike]