RRC Archives

I've edited this post after discussions with others concerning this subject. Thank you all for your input; there have been some enlightening observations.

For years, a few responsible climbers have carried wrenches to tighten bolts on hangers that they found in either a loosened or "low torque" state.

One question that continually pops up is "how much torque should be applied?" The answer depends on the type and size of bolt being tightened. Almost all of the bolts now being use throughout the Red are Grade-5, 3/8-16 bolts or threaded studs and nuts.

If you are using a 6 to 10 inch wrench, then tighten them as much as you can without hanging a blacksmith anvil on the end of the wrench. Better yet, use an accurate torque wrench. For the Grade-5, 3/8-16 bolts, apply 35 foot-pounds.

What IS important is this: When you find a loosened bolt or one you suspect is in a "low torque" condition, please report it immediately to the appropriate developer so that it can be inspected and the torque verified with an accurate torque wrench. At Muir Valley, you can report loose bolts to Tim Powers, Rick Weber, Jared Hancock, Karla Carandang, J.J., or Mike Susko.

Karla has established a database to track the history of every single bolt on every route in the Valley. We are hoping to keep a pedigree on all of the route hardware down here. Please... if you find anything of concern on any route, report it to one of us. And, please be specific as to which bolt on which route.

Thank you all for your help.

Rick

Unless you are interested in the "nuts and bolts" of climbing route hardware, please stop reading here. What follows will bore most of you who are interested only in climbing and not in the stuff you are climbing on.

There have been some recent and important developments in the type and availability of bolts used for attaching hanger brackets. Also, there has been some misunderstanding about how bolts are to be installed. To the best of my ability, the following facts are accurate. If you find this not to be the case, please let me know as soon as possible. Often, I receive conflicting information and have to sort it out. My "Bolting in the Red" book will be updated soon to include this information.

Here is the latest:

1. Rawl 5-piece anchor bolts, size 1/2- are sleeve bolts, either plated or stainless steel, made by ITW/Ramset/Redhead. These have been used for several years to bolt routes in the Red. They are no longer made, and the few remaining in stock are disappearing fast. I believe FIXE USA still has some in stock.

2. Dynabolt Golds, sizes 1/2" x 3.75 and 1/2" x 4.75, are a grade 5 zinc-plated sleeve anchor bolt made by ITW/Ramset/Redhead. Currently, they are one of the most prominently used bolts in the Red. They are no longer made, and the few remaining in stocks are disappearing fast.

3. FIXE double wedge "bolts", size 3/8" X 3 3/4", are stainless steel studs with a nut and washer and with two wedges instead of one. The double wedge doesn't give the bolt stronger pullout strength, but it gives insurance that that maximum pullout strength will be achieved more often. And, it might be more resistant to loosening. These have been found to be especially good in pocketed and soft rock. Like Rawls and Dynabolts, the threaded portion is 3/8" x 16. Unlike Rawls and Dynabolts, they are fitted into a 3/8" dia. hole, rather than a 1/2" dia. hole, and of course, they are not headed. They are currently available from FIXE.

http://www.fixeusa.com/wedge.htm

4. Glue-in bolts have become very popular in other parts of the world with soft stone climbs. They have yet to be used to any extent in the Red. Several will soon be used to replace sleeve bolts on hangers in particularly heavy stressed locations in Muir Valley. Fixe and Petzl offer glue-in products.

IMPORTANT BOLTING INSTRUCTIONS

1. Obtain and read carefully the installation instructions and torque requirements for any bolt you use!

2. Applying a sufficient amount of torque to a bolt is important to obtaining a tight fitting hanger bracket. Ideally, a torque wrench should be used to crank in the factory specified torque for the bolt being used.

3. For 3/8"-16 bolts, which constitute the vast majority of those used in the Red, you should never apply torque above 35 foot-pounds. 35 foot-pounds for Rawls and Dynabolt Golds, and 30 for Fixe double wedge bolts.

4. NEVER use a lubricant, such as wax, grease, or graphite on the threads and between a head or nut and the washer without lowering the applied torque to a value specified by the manufacturer for lubricated bolts. .

5. Holes should be drilled as true as possible. It is very easy to wiggle the drill a little and end up with oversized holes -- especially near the entrance. A bolt installed with room around it tends to loosen when heavily loaded (big whipper). One way to produce a truer sized hole is to drill it with a slightly smaller bit, then follow up with one last quick sizing pass with the correct size bit. For example, drill a 7/16" dia. hole and then follow up with a 1/2" bit for a Dynabolt Gold.

These thoughts comprise most of the additions that will soon be added to the Bolting book. Your comments and suggestions are welcomed and appreciated.

Rick

If you can use a nine inch wrench and twist the head off of a grade five bolt...Hats off to ya!

You're one helluva strongman!!

I believe J-Rock did a torque test with a six inch wrench and couldn't generate anywhere near the amount of torque it would require to sheer a head. He'd have to tell you what the exact torque was. I do and have done a fair amount of route development and rebolting so I guess I have an "experienced" eye, but I must say if you can torque a head off with a six inch wrench (which is what I see most people using for retightining spinners) or even a nine inch wrench, hats off to you. And that guy can hang my draws anyday.

Karla has established a database to track the history of every single bolt on every route in the Valley. We are hoping to keep a pedigree on all of the route hardware down here.

Wow! That's fantastic!

Ultra wrote:If you can use a nine inch wrench and twist the head off of a grade five bolt...Hats off to ya!

You're one helluva strongman!!

Haas wrote:...but I must say if you can torque a head off with a six inch wrench (which is what I see most people using for retightining spinners) or even a nine inch wrench, hats off to you. And that guy can hang my draws anyday.

You guys are right. Tim and I did some testing yesterday and today, and here is what we found: I can twist the head off a 3/8-16 cheap hardware store bolt with a 10" wrench with about 12 inches of breaker bar. Tim could NOT twist the head off a grade-5 Dynabolt Gold (the bolt we actually use), installed correctly, even with a long torque wrench pegged at 60 foot pounds.

So why did I express concern that it was "conceiveable" that one could twist the head off a 3/8-16 bolt? Look at the numbers. The Dynabolt Gold can start to fail in torsion at about 49 foot-pounds of torque. This comes from the charts. Actually, for a zinc plated grade 5 bolt, the number is 37 foot-pounds at 75% of the yield strength. Do the math and this puts yield at 49 foot-pounds.

Now imagine a 9" wrench (.75 foot) being cranked by Keith or some other "really strong" person. Theoretically, to create 49 foot-pounds of torque, a force at the end of the 9" moment arm would only have to be 65 pounds. I could see this strong person being able to apply 65 pounds. Heck, it seems that all one would have to do hang on the wrench, right?

Well, what happens in the real world, I think, is that instead of the torque being solely applied to the 3/8-inch shank, it is partially distributed to the washer and bolt head. This could be proven by putting a bolt in a vise, as I did with the hardware store 3/8-16 and applying ALL of the torque to the shank alone.

But, that isn't the way hanger bolts are installed, so the exercise would be purely accademic.

The bottom line is that I now believe that it is almost impossible that a person tightening a bolted hanger, having a grade-5 3/8-16 bolt, could apply enough torque to twist it off.

Thanks for the feedback, guys. I've edited my original post.

Also, I further edited my original post to remove info about the Trubolt. Even though this is almost identical to the FIXE wedge bolt, experience using it in soft sandstone in the Red has shown this particular bolt to have some serious shortcomings.

Rick

Rick,

Thanks for these informative posts. I learn a ton from your posts on the subject.

I wonder if a Piglet sitting on the wrench could snap it off?

Unfortunately I can see someone trying to hang off of a wrench with the mistaken idea that it makes the bolt hold stronger.

thanks for the info Rick, I appreciate all the saftey testing you do down there at Muir

I still want to see if I can sheer the head off of a dynabolt in a practice situation just for fun... Grr... 60 pounds.... Grrr... 65 pounds... Grrrr.... 70 pounds.... Grrrrr....