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Gunkiemike · · Unknown Hometown · Joined Jul 2009 · Points: 2,795
Carl Sherven wrote:I guess my question is "Why?" Why even give galvanic reactions a chance? You're spending the $$$ to make an all S/S setup to the anchor chains. Why not spend the extra few dollars to buy S/S quicklinks and chains? I'm seriously curious about this myself.
I'm not a metallurgist either, but I am a chemist.

I can offer one sound reason to put plated chains on SS anchors - so the corrosion has a place to take place. I accept that under the influence of the weather, acid rain etc, SOMETHING is going to corrode. According to well-understood chemistry, the most active metal is going to get oxidized. Aluminum is very active, so Al hangers are bad. Zinc is more active than steel, that's why it's used in galvanizing - the zinc is oxidized and so protects the steel. In underground fuel tanks, there is a strip of active metal somewhere for this same reason. It's called the sacrificial anode and needs to be replaced from time to time. Same deal with the unpainted magnesium tab on the lower end of outboard motors.

Anyway, if everything (bolt, hanger, chain) is SS you don't know where the corrosion will occur, but the wettest parts are the most likely sites. So hang a plated chain (or at the least, screw links) on it, and watch them rust. That tells you the stainless bits are good. When things look bad, replace the chains/links. The bolts are still good.
Darren Mabe · · Flagstaff, AZ · Joined Dec 2002 · Points: 3,780
Carl Sherven wrote:Why not spend the extra few dollars to buy S/S quicklinks and chains?
its more than just a few extra dollars to go all SS...
20 kN · · Unknown Hometown · Joined Feb 2009 · Points: 1,346
Gunkiemike wrote: I'm not a metallurgist either, but I am a chemist. I can offer one sound reason to put plated chains on SS anchors - so the corrosion has a place to take place. I accept that under the influence of the weather, acid rain etc, SOMETHING is going to corrode. According to well-understood chemistry, the most active metal is going to get oxidized. Aluminum is very active, so Al hangers are bad. Zinc is more active than steel, that's why it's used in galvanizing - the zinc is oxidized and so protects the steel. In underground fuel tanks, there is a strip of active metal somewhere for this same reason. It's called the sacrificial anode and needs to be replaced from time to time. Same deal with the unpainted magnesium tab on the lower end of outboard motors. Anyway, if everything (bolt, hanger, chain) is SS you don't know where the corrosion will occur, but the wettest parts are the most likely sites. So hang a plated chain (or at the least, screw links) on it, and watch them rust. That tells you the stainless bits are good. When things look bad, replace the chains/links. The bolts are still good.
FYI, there are alloys that are completely impervious to corrosion. Grade 2205 stainless steel in a non-marine environment lasts, well, pretty much forever; or at least a really long time. Above that, there are pure titanium alloys, as they call it, which is a light alloy containing mostly titanium. These alloys can last even longer. We use grade 4 and 6 titanium alloyed bolts at our crag. The manufacturer conservatively tells us we can expect upwards of a 100 year lifespan from them, even if they are mixed with stainless steel chain links, and that is in a marine environment. When placed outside of a marine environment, titanium alloyed bolts may very well outlast the sport. I would thank that by the time they would need replacement, climbing equipment technology would have advanced so far that bolts are no longer used. :P
Jim Titt · · Germany · Joined Nov 2009 · Points: 490
Gunkiemike wrote: I'm not a metallurgist either, but I am a chemist. I can offer one sound reason to put plated chains on SS anchors - so the corrosion has a place to take place. I accept that under the influence of the weather, acid rain etc, SOMETHING is going to corrode. According to well-understood chemistry, the most active metal is going to get oxidized. Aluminum is very active, so Al hangers are bad. Zinc is more active than steel, that's why it's used in galvanizing - the zinc is oxidized and so protects the steel. In underground fuel tanks, there is a strip of active metal somewhere for this same reason. It's called the sacrificial anode and needs to be replaced from time to time. Same deal with the unpainted magnesium tab on the lower end of outboard motors. Anyway, if everything (bolt, hanger, chain) is SS you don't know where the corrosion will occur, but the wettest parts are the most likely sites. So hang a plated chain (or at the least, screw links) on it, and watch them rust. That tells you the stainless bits are good. When things look bad, replace the chains/links. The bolts are still good.
You are misunderstanding electrolytic corrosion. In a suitable medium such as water two different materials have differing potentials and the anode is stripped of ions which transfer to the cathode or are washed away in the water. There is no need for oxidisation to occur and galvanic corrosion works perfectly in oxygen-less environments. A rusting chain tells you nothing about corrosion to the other components.
Nearly all the stainless alloys are very near to each other on the galvanic scale and will cause no galvanic reaction.
Rusting chains look like shit!
J. Albers · · Colorado · Joined Jul 2008 · Points: 1,791

Hey Jim,

I know we disagreed in a previous post (no hard feeling here by the way), but considering you seem to be quite knowledgeable on the topic, did you see my post on the last page? Any chance that you have an opinion?

Thanks.

Gunkiemike · · Unknown Hometown · Joined Jul 2009 · Points: 2,795
Jim Titt wrote: You are misunderstanding electrolytic corrosion. In a suitable medium such as water two different materials have differing potentials and the anode is stripped of ions which transfer to the cathode or are washed away in the water. There is no need for oxidisation to occur and galvanic corrosion works perfectly in oxygen-less environments. A rusting chain tells you nothing about corrosion to the other components. Nearly all the stainless alloys are very near to each other on the galvanic scale and will cause no galvanic reaction. Rusting chains look like shit!
Sorry, I am using the term "oxidation" in its purest chemical sense. The anode being "stripped of ions" is indeed oxidation (increase in the element's oxidation number) even in the absence of oxygen. So rusting, chloride pitting and I imagine even stress corrosion are all oxidative processes. Dissimilar metals are not needed for oxidation to occur, but having dissimilar metals will locate the site where it does occur.
Brian in SLC · · Sandy, Utah · Joined Oct 2003 · Points: 14,421

What's kind of interesting with respect to all this chatter about galvanic corrosion, is, there is very little to no evidence of it at any crag in the U.S. between plated and stainless steel.

I've seen what I thought looked like galvanice on old (60's vintage more than likely) alumunum cave hangers on plated steel studs, which were pulled and replaced on a route, and, I got a good look at the hangers. The backside of the hanger, in and around the contact area of the bolt, had corroded with deep pitting that looked related to the contact with the bolt.

The Index aluminum hangers don't look like "sacrificial" anodes to me, or, to a high end metallurgist I showed the photo's to a few years back (exfoliation corrosion more than likely).

Here's a similar hanger on the Med at Capo Noli in Finale Ligure:

Aluminum hanger Capo Noli Finale Ligure

You can see that the area around the bolt is still hanging in there. If there was a "sacrificial anode" thing happening, I'd think the bolt/hanger contact area would go first. Looks like exfoliation corrosion to me.

Here's another aluminum hanger on a 1972 route nearby, but, away from the marine coast:

Rocca di Corno Finale Ligure aluminum hanger 1972

Seemed kinda ok.

Yeah, rusty chains aren't so good:

Schoolroom rappel, Little Cottonwood

J. Albers · · Colorado · Joined Jul 2008 · Points: 1,791

Thanks for the detailed reply Brian. In short, I really need not worry nor feel like a cheap ass for matching zinc plated chains (etched and painted) with an all SS bolt and hanger setup. Check.

...and yes, the stain from the rusty chain in the picture you posted is indeed an eyesore. Bet you could see that from the ground.

Thanks again.
Cheers.

Brian in SLC · · Sandy, Utah · Joined Oct 2003 · Points: 14,421

Was a trend for awhile to soak shiny, new chain in vinegar to remove the zinc plating, which, also removes most of the corrosion protection. They rust like the dickens, even in a dry climate.

Best to get a primer compatible with zinc, paint with that, then top coat with some camo paint. Even if the paint chips, won't look as bad as unpainted and shiny chain, or, super rusted chain.

Cheers!

Brian in SLC · · Sandy, Utah · Joined Oct 2003 · Points: 14,421
Darren Mabe wrote: its more than just a few extra dollars to go all SS...
Yeah, kinda.

With the occasional good deal on stainless powerbolts, or, Hilti KBIII's, I can keep that cost down per bolt. Hangers? Not a huge leap to stainless.

Stainless chain and rapides, especially 5/16", aren't too bad if you look around for a good deal.

But, yeah, it costs more. I guess I think the routes should be worth it.
mattm · · TX · Joined Jun 2006 · Points: 1,395
Brian in SLC wrote:Was a trend for awhile to soak shiny, new chain in vinegar to remove the zinc plating, which, also removes most of the corrosion protection. They rust like the dickens, even in a dry climate. Best to get a primer compatible with zinc, paint with that, then top coat with some camo paint. Even if the paint chips, won't look as bad as unpainted and shiny chain, or, super rusted chain. Cheers!
You want LATEX spray paint. Normal spray paint (primer and final coat) has chemicals that react with the zinc to form a "soap" layer. That's why the paint never sticks. Latex spray paints lack this chemical so they adhere a lot better. They'll still chip of course but seem to hold up better. You want to allow SEVERAL days for the paint to dry and harden. It's bet to prepare your hardware well in advance so the paint is as hard and dry as possible. This greatly extends longevity.

I'll typically use a SS quick link when it will be in contact with a SS glue in. I don't want any corrosion occurring on the Glue In. With hangers that are easily replaced, I'll do PS Quicklinks more often.
J. Albers · · Colorado · Joined Jul 2008 · Points: 1,791
Brian in SLC wrote:Was a trend for awhile to soak shiny, new chain in vinegar to remove the zinc plating, which, also removes most of the corrosion protection. They rust like the dickens, even in a dry climate. Best to get a primer compatible with zinc, paint with that, then top coat with some camo paint. Even if the paint chips, won't look as bad as unpainted and shiny chain, or, super rusted chain. Cheers!
Yeah, you can indeed buy etching primer that is specifically used for plated steel and thus does not remove the corrosion protection. This way you get the benefit of rust protection without the problem of the paint chipping off after a couple of seasons. In one of my local areas that gets quite a bit of runoff, the chains treated in this way are at least ten years old, but they look brand new. So it seems to work rather well.
Cheers.
20 kN · · Unknown Hometown · Joined Feb 2009 · Points: 1,346
Brian in SLC wrote:What's kind of interesting with respect to all this chatter about galvanic corrosion, is, there is very little to no evidence of it at any crag in the U.S. between plated and stainless steel. I've seen what I thought looked like galvanice on old (60's vintage more than likely) alumunum cave hangers on plated steel studs, which were pulled and replaced on a route, and, I got a good look at the hangers. The backside of the hanger, in and around the contact area of the bolt, had corroded with deep pitting that looked related to the contact with the bolt. The Index aluminum hangers don't look like "sacrificial" anodes to me, or, to a high end metallurgist I showed the photo's to a few years back (exfoliation corrosion more than likely). Here's a similar hanger on the Med at Capo Noli in Finale Ligure: You can see that the area around the bolt is still hanging in there. If there was a "sacrificial anode" thing happening, I'd think the bolt/hanger contact area would go first. Looks like exfoliation corrosion to me. Here's another aluminum hanger on a 1972 route nearby, but, away from the marine coast: Seemed kinda ok. Yeah, rusty chains aren't so good:
So what type of corrosion would you name in your second picture? Uniform corrosion? I am under the understanding that your second picture is a textbook example of galvanic corrosion. I have seen cases where carbon steel hangers with carbon steel bolts outlast stainless steel hangers with carbon steel bolts. If uniform corrosion was to blame, the plated steel hangers and bolts would rust at the same rate as the mixed bolts. So if galvanic corrosion is not an issue in the USA, why is it possible for all carbon steel bolts to outlast stainless hangers paired with carbon steel bolts?
Adam Stackhouse · · Unknown Hometown · Joined Jan 2001 · Points: 13,210
meigsrock wrote:I am planing on puting up some routes on a new wall and am wonering if I can hand place them, use my standard cordless drill, or if I need to throw down some serious coin for that fancy climbing hammer drill that is on the market. I have the rawl 5 pc bolts but need to get a drill. Any suggestions?
I tried that too and it didn't work. Gotta go with a hammer drill. I bought a Bosch Annihilator that was factory refurbished for something like $350 plus shipping. 4 inch hole into California granite takes about 20 seconds.
Brian in SLC · · Sandy, Utah · Joined Oct 2003 · Points: 14,421
20 kN wrote:So what type of corrosion would you name in your second picture? Uniform corrosion? I am under the understanding that your second picture is a textbook example of galvanic corrosion. I have seen cases where carbon steel hangers with carbon steel bolts outlast stainless steel hangers with carbon steel bolts. If uniform corrosion was to blame, the plated steel hangers and bolts would rust at the same rate as the mixed bolts. So if galvanic corrosion is not an issue in the USA, why is it possible for all carbon steel bolts to outlast stainless hangers paired with carbon steel bolts?
Second pic I see the standard reddish rusty looking iron oxide from that bolt.

If you have pic's or a reference to some bolts that faired better than a stainless hanger, I'd like to see it. i never have. Ain't sayin' it can't happen, but, wouldn't the carbon steel be the anode?
Carl Sherven · · Unknown Hometown · Joined Dec 2007 · Points: 210

This was a pretty cool thread until everyone started letting a troll derail the whole thing. Account created May 21, 2012, has added 6 inflammatory comments to pictures, and made 72 forum posts, all of which that I've seen have been inflammatory. Just ignore it and think of how bad life must suck if saying nasty things to people on the internet is the best thing you can think to do with your evenings.



So back to the galvanic reaction stuff, I have a question for some of you that obviously know more than me. Is it reasonable to use aluminum bus bars in high current electrical applications if they have to mate with copper bus bars? I know that if you don't add some flashing it causes a reaction, which leads to a high impedance connection, and all the problems that come with that. Some utilities actually tried to incorporate Al bus bars back in the 60s, but they had several failures (including a couple substation fires) where the Al mates with the Cu, but I don't think there was any flashing or other coating on the bars. If you add a silver or tin flashing to both bus bars is it possible to mate them without galvanic reaction?

Let's get this thread back on track.
20 kN · · Unknown Hometown · Joined Feb 2009 · Points: 1,346
Carl Sherven wrote:This was a pretty cool thread until everyone started letting a troll derail the whole thing. Account created May 21, 2012, has added 6 inflammatory comments to pictures, and made 72 forum posts, all of which that I've seen have been inflammatory. Just ignore it and think of how bad life must suck if saying nasty things to people on the internet is the best thing you can think to do with your evenings. So back to the galvanic reaction stuff, I have a question for some of you that obviously know more than me. Is it reasonable to use aluminum bus bars in high current electrical applications if they have to mate with copper bus bars? I know that if you don't add some flashing it causes a reaction, which leads to a high impedance connection, and all the problems that come with that. Some utilities actually tried to incorporate Al bus bars back in the 60s, but they had several failures (including a couple substation fires) where the Al mates with the Cu, but I don't think there was any flashing or other coating on the bars. If you add a silver or tin flashing to both bus bars is it possible to mate them without galvanic reaction? Let's get this thread back on track.
I used aluminum bars to join 10 automotive batteries in a vehicle awhile back. I had five 2/0 AWG wires terminated with copper lugs on the bar. I was drawing about 1500 amps RMS among the five lines. Anyway, I used that battery system for three years and I never had any corrosion issues. I did not use any type of electrolytic gel or any of that stuff between the connections either. I am also not the first person to do this. In the application I was using those batteries in the method I chose, with the Al bars and Cu lugs, is very common. I have never heard of anyone having issues except for when they do not tighten the connections well enough, or seize the screws, in which they get extreme heat, sometimes leading to a fire.
Carl Sherven · · Unknown Hometown · Joined Dec 2007 · Points: 210
20 kN wrote:I used aluminum bars to join 10 automotive batteries in a vehicle awhile back. I had five 2/0 AWG wires terminated with copper lugs on the bar. I was drawing about 1500 amps RMS among the five lines. Anyway, I used that battery system for three years and I never had any corrosion issues. I did not use any type of electrolytic gel or any of that stuff between the connections either. I am also not the first person to do this. In the application I was using those batteries in the method I chose, with the Al bars and Cu lugs, is very common. I have never heard of anyone having issues except for when they do not tighten the connections well enough, or seize the screws, in which they get extreme heat, sometimes leading to a fire.
That's kind of what I'm getting at; it's common to use compression lugs that have an electro-tin plating with wires made of either Al or Cu. It's also common to fasten these lugs onto either Al or Cu bus bars. Of course, when a lug is not plated it is typically only rated for use with the same metal as it is made from, for example here's one lug series from Ilsco that is not plated or flashed, and it is only rated for use with copper wires. On the other hand, here's another compression lug series from Ilsco that has an electro-tin plating, and it's rated for use with either metal. The same thing can be found with just about every terminal for headers, terminal blocks, circuit breakers, etc. They are electro-tin plated, and there is no issue with using either Al or Cu wires with them. However, for some reason when you bring up the idea of mating Al bus bars with Cu bus bars, using an electro-plating to prevent a galvanic reaction, people balk at the idea. I don't understand why we do this in every other facet of wiring, but when we try to apply the same technique to bus bars people get all weird.
Jim Titt · · Germany · Joined Nov 2009 · Points: 490
J. Albers wrote:Thanks for the detailed reply Brian. In short, I really need not worry nor feel like a cheap ass for matching zinc plated chains (etched and painted) with an all SS bolt and hanger setup. Check. ...and yes, the stain from the rusty chain in the picture you posted is indeed an eyesore. Bet you could see that from the ground. Thanks again. Cheers.
There are worse things in the climbing world to worry about than a galvanised chain on a stainless hanger for sure. I´ve seen enough yachts with mixed stainless/galvanised rigging components including my own not to worry about it being an issue. If one wants to be sure there is no galvanic action then a brief test with a millivolt meter is standard practice anyway.

There is a discussion going on in Sardinia over the use of galvanised bolts (which are common in France) and one of the major objections is that on limestone the zinc leaches down the rock killing the algae leaving white lines on the cliff, the inevitable rust which appears later adds to the visual effect in a somewhat unnatractive way though it saves time making photo topos.
Brian in SLC · · Sandy, Utah · Joined Oct 2003 · Points: 14,421
Jim Titt wrote: There is a discussion going on in Sardinia over the use of galvanised bolts (which are common in France) and one of the major objections is that on limestone the zinc leaches down the rock killing the algae leaving white lines on the cliff, the inevitable rust which appears later adds to the visual effect in a somewhat unnatractive way though it saves time making photo topos.
Yeah, seen the streaks at a fair number of crags in France. Seems like there's been a lot of replacement effort going to stainless.

Bolt streaks at Mont Sainte Victoire, France

Also, you can see it even in fairly dry areas in the U.S. too...

Bolt streaks, Northern Arizona limestone
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