A cautionary Tale of Two Metals - and a bolt that pull out after just 15 years

I recently revisited an area I bolted and climbed in the summer of 1999 and discovered that I had mistakenly used stainless hangers (Petzl) with zinc plated bolts. So today I rebolted a couple of routes and discovered this... The first bolt I went to chop seemed normal (took many hits back and forth to get it to break), but when I used the claw on my hammer to try and break the bent tip off the bolt, THE WHOLE BOLT just easily pulled out! This has never happened to me before (and I tried to pull the others on that route but couldn't). Here is a photo (good quality granite, on a relatively dry cliff in arid Eastern Washington).

Obviously the plated bolt rusted and decomposed enough in the 15 years since placement to fail. I'm not sure this had anything to do with the fact it was mated with a stainless hanger. I think it is simply that its a plated bolt, and that the wedge part corroded enough not to hold any longer. Later on another bolt (also in a dry spot) snapped off after just a few hits back and forth - way sooner than I've ever experienced before. This may be as a result of the dissimilar metals.

This is all very sobering for me, and confirms my current practice of using only stainless steel bolts and hangers.

"Galvanic" type corrosion -- with 2 different metals, seems to manifest mainly in dramatically corroded hangers (like in the Bad Old Days of aluminum hangers).
You probably have a simple example of the wrong type of anchor being used. While stud type anchors do torque down in very hard rock, theres not much holding that baby in place -- just a small tip! Plus -- Industry standards specify a sleeve-type anchor if there will be vibratory action. Does the "flutter" of dynamic rope function constitute "vibration"? Maybe you have proved it does? Why take chances?!
While many climbers use such anchors (they are cheaper, especially in SS), there have been many failures
like yours -- especially in softer rock, like limestone. But even "granite" can have many variations in hardness in a given area -- especially if it's somewhat metamorphic.
By far the best, safest, most modern -- and coolest-- solution is to use glue-ins. Voila !-- all your problems will vanish.
Thanks for rigging routes for us......

As you don't state what brand bolt or where you bought them from, probably safe to assume that you bought shit bolts and good hangers. I don't see corrosion in the photo.

Rethink that please.

Look at the photo of the bolt. There is no apparent corrosion where the hanger is touching the threads. How do you account for that within your theory of galvanic corrosion? Are you suggesting that where the dissimilar metals were touching, that's fine, but all the way at the end of the bolt it corroded because of dissimilar metals ? Can't see that myself from your evidence. Looks like you went to the hardware store and bought cheap Chinese wedge anchors.

applewood wrote:I recently revisited an area I bolted and climbed in the summer of 1999 and discovered that I had mistakenly used stainless hangers (Petzl) with zinc plated bolts. So today I rebolted a couple of routes and discovered this... The first bolt I went to chop seemed normal (took many hits back and forth to get it to break), but when I used the claw on my hammer to try and break the bent tip off the bolt, THE WHOLE BOLT just easily pulled out! This has never happened to me before (and I tried to pull the others on that route but couldn't). Here is a photo (good quality granite, on a relatively dry cliff in arid Eastern Washington). Obviously the plated bolt rusted and decomposed enough in the 15 years since placement to fail. I'm not sure this had anything to do with the fact it was mated with a stainless hanger. I think it is simply that its a plated bolt, and that the wedge part corroded enough not to hold any longer. Later on another bolt (also in a dry spot) snapped off after just a few hits back and forth - way sooner than I've ever experienced before. This may be as a result of the dissimilar metals. This is all very sobering for me, and confirms my current practice of using only stainless steel bolts and hangers.

Hi Rusty, I don't think the wedge type anchor is the problem - I've placed about 5000 of those kinds of 3/8" bolts on granite and gneiss and have never had a bolt fail before. This route had probably been climbed only a couple of times in the past 15 years... so it most likely is erosion of the plated bolt. Still it is a bit of a mystery for me and sobering that a basically unused bolt can fail in an arid climate in just 15 years.

No mystery to me. Look at it:

No corrosion on the threads. They're fine. You have a piece of crap bolt, one that was most likely not ICC approved. Do you believe that it ICC (1998 would be ICBO) approved? I doubt it.

Billcoe has a good point here. What brand of bolts did you use?

Hi Billcoe, I agree it probably is a situation of a shit bolt and quality hanger - and I don't see any galvanic type erosion either (and never said there was any on that bolt). I don't remember where I got the bolts...15 years sure seems like a long time ago now, yet I replaced over a dozen of these today and none of them pulled like this first one. This is the first old bolt I've ever seen the "inside" of - and all I can think is that the wedge sleeve must have rusted enough to get smaller (obviously it was a tight fit to begin with).

It was the second bolt I mentioned that broke off quickly that I wondered if it maybe had some galvanic damage.

I don't disagree on mixing metals, but I've learned it's usually not a big deal like I once thought it was. If you have an aluminum hanger and any other kind of a bolt, thats a huge issue. But look at these:

This bolt was stainless, and an unplated steel homeade hanger was put on it in teh wettest part of the Columbia River gorge (wet indeed) where it stayed for 20 years, moss covered towards the end.

Still perfectly strong.

Close up of Tim Olsen, local guidebook author and good dude to hang with - he remembered the location. It was invisible but he dug and found it. Look at the plants. Wet eh?



See? The stainless wedge anchors look perfect still. The hanger, being homemade, probably always looked like crap, but it's still plenty strong.

Here's one I found is a huge ticking time bomb we all need to avoid. The steel 5 piece Powers anchors will corrode right where the threads meet the body of the bolt. You can't do a visual inspection as it is below grade. Even within a year I've gone back to replace with stainless and the 5 pieces were looking real real bad. Corroded badly.

That's all I have. Take care all and don't blindly trust old bolts is a good motto to have:-)

Billcoe, I was thinking maybe that the plated bolt was the weak link. I imagine a stainless bolt would last a long time - yet this is the sobering part since I've placed thousands of plated wedge anchors (mostly 20 to 15 years ago) and now wonder what condition they are in...

Hah! I can relate. The longest route in Oregon is reputed to have bolts that will fail under body weight. They were plated Rawl drives. Made in the USA. I do not think it has seen a second ascent yet, however, it's only been 30 some odd years. West Face of the Matterhorn in the Wallowas.

Around here, Joseph Healy did an inventory at Beacon Rock and replaced all the bolts (they were a mish mash of all brands and sizes placed by many folks over many years) with new stainless steel wedge (icc approved of course) anchors. Every damned one.

Whew. Lot of work. However, all doubt is gone.

As an aside, the Rawl Wedge anchors were Grade 5 material. Stout stuff. Most others were mild steel (grade 2), you can tell when you pound or saw on the old ones which it is.

I agree with everyone else in this thread so far. I don't see any evidence of galvanic corrosion. It was either a bad bolt or poor rock.

Billcoe, I used Rawl split wedge anchors when I first started placing bolts (all hand drilled) in the early 90's. Now I wonder how much rebolting I need to do... (this is definitely NOT a corrosive environment).

What/where is this good granite cragging in e Washington? I'm always looking for alternatives to vantage for when the clouds come back on the wet side.

Hi Bruce, I agree that this probably isn't galvanic corrosion - it was simply the dissimilar metals that got my attention and caused me to rebolt the route. The rock is excellent so its obviously the bolt - yet it went in and held fine initially. The way it just easily pulled was the weird part - and a warning to all of us who climb bolted routes and blindly trust them.

HI Aaron, this route is in the Kettle Valley (part of the Okanogan region) - lots of good granite in these parts.

Thanks Steve.

Thanks a bunch for the heads up. Will have to check it out when of these days.

Steve Levin wrote:A group of folks active in re-bolting has set-up a Google group called "Sustainable Bolting". Lot's of discussion on techniques and tools. Gregger Man knows more if you want to get involved...

Can I get an invite?

Done and In! Thanks!

Applewood is right that many wedge bolts have been used successfully, but I've just had too many fail to torque down, even when I thought the rock I was drilling was pretty hard. I thought it may be partly a dirty hole so I started brushing and blowing the holes more carefully. The other annoying thing about them is that the securing nut easily comes loose with hanger torque, to give you a spinner. Guess Red Loctite will fix that.
5 piece Rawl/Powers sleeve anchors hold real well and are super reliable, but, with all those pieces, they do corrode quite quickly. And they are brutally expensive in SS.
Back to the failure:
If this WAS a generic bolt:-
The snapping-off or chopping strength is related to the ductility or malleability of the metal. If the metal is too hard it will snap rather than bend. It's common to snap one of these bolts with a single blow - sometimes it seems a heavy fall could have done that. Others will bend back and forth several times. It's hard to tell for sure, as the industry markings are somewhat obscure, but my guess is that the more malleable, reliable bolts are the custom made climbing types.
Other things that could lead to a brittle bolt are a bad metal batch, poor or inadequate heat treatment or heat relieving and a general lack of quality control. This is what you get with generic hardware store bolts.
It's true that companies like Powers and Hilti produce wedge anchors that meet industrial standards, tho these standards are not designed around climbing.
The best thing for everybody is to stick with custom made climbing bolts ( and suck up the extra price by drinking cheaper beer? ).
Final thoughts about galvanic action:
This is a very complex can of worms but it seems that to get serious corrosion you have to be far apart on the table -- such as with aluminum and steel. SS and galvanized steel are not THAT different.
Thats another place glue-ins rule --- being one piece, they escape this problem.
Here in the NorthWest, with all the rain and vegetation (maybe not the ScabLands), we do have to be watchful of corrosion. It's not anything as bad as Thailand but it's a serious factor.
Bolting can be a major headache, but it provides some nice moves.....

Thanks Rusty for the thoughtful reply. I'm glad that the galvanic risk is apparently very low here, but still always on the lookout for mis-matched hardware (and I'm guilty of doing it a few times in the 90's when I just didn't know better).

What I observed with the pulled bolt was weathering deep in the hole which could maybe explain its lack of holding power. It didn't snap off easily when I was hammering on it (maybe 8 bends back and forth and it still was strong enough to hold the hammer claw and pull the whole bolt free). The bolt would not likely ever have had an outward force (steep slab placement), but needless to say its disconcerting.

Only one bolt I chopped yesterday (out of 11) broke quickly/easily. Maybe it was simply from inconsistent metal (they were all the same brand and size bolt) - and given the environment thats a more likely explanation than galvanic corrosion.

I imagine that stainless bolts will erode slower (within the rock) - and am reassured that my choice to only use them now (even in this very dry environment) is a sound one and worth the extra expense, but wonder if a combination of cheaper wedge bolts with some glue would work too (and so seal the hole from water)?

I guess my initial point is we should all be looking for bad bolts (usually invisible on the surface) everywhere we climb. Unfortunately this creates a whole new level of uncertainty....kind of like the HIV of climbing..