painting hangers

gription wrote: I think that is a very narrow mined opinion. Clearly a properly treated and maintained piece of gear is more resistant to corrosion. It just remains to discover and apply the correct materials and maintenance process. I believe this merits study.

Excuse me? I have a "narrow mined" (sic) opinion?! I actually have an well informed opinion due to the fact that I've studied bolt corrosion and learned from professional metallurgist/climbers for 16 years.

I've written three published articles on climbing bolt corrosion (Climbing, Rock & Snow (Japan) and the ACMG Journal), and am writing an updated article for the ASCA to replace the one I wrote for them in 2001.

I led the team that developed the world's first titanium bolt back in 1999-2000. I have been tracking bolt corrosion all over the world for 16 years and have debated the pros and cons with professionals.

I get emails (Brazil, Taiwan, Meditteranean, Canada, US, etc.) every few months with photos of corroded bolts, wherein people ask me for my "narrow mined" opinion.

In other words, Gription, I actually know what I'm talking about, and it's not just me that thinks that.

Just so you know, passive coatings of all types were discussed at length by the UIAA Safety Committee back in 2002. The conclusion was that they were NOT appropriate for climbing bolts due to the fact that they could be cracked or damaged in normal use or installation, and that corrosion would then proceed more aggressively UNDER the coating.

In the same vein, Jim Titt gave the details why painting stainless steel is a bad idea in his well informed post.

John, stop feeding. That is all.

You could start by using climb tech wave or bolt product glue ins, much lower visual impact to begin with. Just be sure to cover up your glue if using hilti, if your rock is grey ac100+ gold can match pretty well from the get go. Overdrill the hole a bit, so you don't have to hammer on your new paint job.

It seems to me that the washers on the bolt often rust easily. Will a rusty washer lead to hanger corrosion?

bus driver wrote:It seems to me that the washers on the bolt often rust easily. Will a rusty washer lead to hanger corrosion?

If the washer is rusting then it is probably not stainless, so if it is used in conjunction with a stainless hanger than yes it will accelerate the hanger corrosion due to galvanic corrosion between the dissimilar metals.

kennoyce wrote: If the washer is rusting then it is probably not stainless, so if it is used in conjunction with a stainless hanger than yes it will accelerate the hanger corrosion due to galvanic corrosion between the dissimilar metals.

Uhhh...you mean...since the washer would be the sacrificial anode...it would reduce the corrosion on the hanger...ha ha...

In the case of very shiny SS bolts, what would be an appropriate intervention to dull the luster?

Is it OK to sand/wire brush/bead blast them and just leave them like that? It would take off the outside shine layer but if left uncoated oxygen would still be available to form a new protective barrier. Is that how this works?

Maybe titanium glue ins are most appropriate everywhere due to their lack of luster?

kennoyce wrote: If the washer is rusting then it is probably not stainless, so if it is used in conjunction with a stainless hanger than yes it will accelerate the hanger corrosion due to galvanic corrosion between the dissimilar metals.

Is it acceptable to use a silicone (hard plastic) washer instead of the steel washer provided with the bolt. I've seen a lot of SS bolts (powers) that seem to have a non SS washer.

With a plastic washer, this would be a non issue. Making sure the bolt diameter matches perfectly to the hanger would be more important but you should already do that.

Glue-in is a viable way to avoid the ugliness of shiny hangers.
Wave-bolts ( wavebolt.com/ ) are making headway at Rumney and I have to say they are not conspicuous even on Day 1 (right after they were placed).

highaltitudeflatulentexpulsion wrote:In the case of very shiny SS bolts, what would be an appropriate intervention to dull the luster? Is it OK to sand/wire brush/bead blast them and just leave them like that? It would take off the outside shine layer but if left uncoated oxygen would still be available to form a new protective barrier. Is that how this works? Maybe titanium glue ins are most appropriate everywhere due to their lack of luster?

A lot of stainless hangers are electropolished which makes them very shiny, if you chemically passivate them they will have a duller "frosty" finish. Normally you would dull the finish by pickling in a mixture of nitric and hydroflouric acid, then wash clean and passivate using either nitric or citric acid.
The easiest way for the hobby metalworking is to buy some welders stainless steel pickling paste for the first step and then use citric acid afterwards. Both are fairly vile jobs so it´s easiest to go to any stainless fabricator and get him to do it.
We achieve a satin matte finish by abrasive tumbling first then passivating, so-called barrel finish.

Brian in SLC wrote: Uhhh...you mean...since the washer would be the sacrificial anode...it would reduce the corrosion on the hanger...ha ha...

Except for the fact that it would end up pitting the hanger where it contacts the washer which would lead to crevice corrosion. The sacrificial anode theory is all great and good, but in practice it doesn't actually work.

Good information from lots of knowledgeable people on here. Are there some photos out there of galvanic corrosion in action on bolts/hangers or other bolt corrosion from painting hangers?

kennoyce wrote: Except for the fact that it would end up pitting the hanger where it contacts the washer which would lead to crevice corrosion. The sacrificial anode theory is all great and good, but in practice it doesn't actually work.

Hmmm.

I've never seen a pitted hanger from galvanic corrosion. Have you? Post a pic if you have one.

Also, zinc plating? Seems like if the "sacrificial anode theory" doesn't actually work, then, every plated hanger and bolt wouldn't be, ahh, plated. Just wouldn't be necessary.

I've pulled a fair number of rusty carbon steel bolts attaching stainless hangers...never noticed pitting of the hanger, or, what I'd think was excessive corrosion that might be attributed to a galvanic situation. Maybe in more humid climates? Plus, I've always wondered about the surface area difference between the metals as a player in the rate of corrosion. Big sheet of stainless steel with a couple of small carbon steel fasteners? Yeah, that'd be bad. Stainless hanger versus carbon steel bolt? Hmmm. Not sure. Not as big of a surface area difference.

Given that most fasteners are zinc plated, when the zinc sacrifices itself, I'd imagine that effects the potential of a galvanic cell.

I'm all for not mixing metals especially for fixed anchors in climbing. Especially aluminum hangers and steel bolts. But, plated carbon steel and stainless? I'm just not convinced is a huge deal. There's gobs and gobs of stainless hangers and carbon steel bolts/studs out there...

Bolt pulled from Lower S Curves, Big Cottonwood Canyon. Placed 1990, pulled 8/11/2003.

Bolts pulled from Division Wall in American Fork Canyon. Placed 1991? Pulled 10/23/2004.

Anchor bolt on Glass Ocean in Big Cottonwood Canyon. Fixe stainless hanger and grade 5 Rawl/Powerbolt.

highaltitudeflatulentexpulsion wrote: Is it acceptable to use a silicone (hard plastic) washer instead of the steel washer provided with the bolt. I've seen a lot of SS bolts (powers) that seem to have a non SS washer. With a plastic washer, this would be a non issue. Making sure the bolt diameter matches perfectly to the hanger would be more important but you should already do that.

Do not use plastic washers. You have got to be trolling here. SS 5 Piece Rawl Bolts come with SS washers, if you are using something else you can pick up some SS washers from the store.

Erik Kloeker wrote: Do not use plastic washers. You have got to be trolling here. SS 5 Piece Rawl Bolts come with SS washers, if you are using something else you can pick up some SS washers from the store.

I've never done it so you can relax.

I am just thinking aloud here, why not. Powers washers are often not SS even on SS bolts, I don't know why but it happens. If your bolt matches the hanger, there won't be loss in strength. If you use a thin washer, it won't give you future issues of loosening. If you use the 2.75" Powerbolt, then the blue sleeve would be touching the hanger. It seems like a perfect combo to keep the bolt from touching the hanger at all.

Many washers at the store are labelled SS. This can mean a few different things. Ask Jim or John but I have to wonder if mixing 303 SS with 304 or 316 can cause similar electrolyte issues as carbon and ss or galvanized and ss.

thanks for the pics and for replacing those bolts in the wasatch. I think I've clipped everyone of them. Seeing them though I can't say I'd be worried about any of them shearing through due to corrosion. What shape were the sleeve components in that would affect pullout strength in a roof for instance?

I'm having a hard time believing a plastic washer wouldn't just crack, some are going to disagree here but you really don't need a washer if using a 3/8th hole hanger and 1/2" power bolt. The hanger itself acts as the washer. It's a very common setup here in RRG.

Erik Kloeker wrote:some are going to disagree here but you really don't need a washer if using a 3/8th hole hanger and 1/2" power bolt. The hanger itself acts as the washer. It's a very common setup here in RRG.

It's common everywhere and I absolutely agree with you. That's the whole point of my post. Since it wouldn't weaken anything, why not. It could prevent metal on metal.

If the gasket on the drain plug of my vehicle only cracks about once every 20 years, I think a silicone washer would hold up just fine.

Brian in SLC wrote: Hmmm. I've never seen a pitted hanger from galvanic corrosion. Have you? Post a pic if you have one. Also, zinc plating? Seems like if the "sacrificial anode theory" doesn't actually work, then, every plated hanger and bolt wouldn't be, ahh, plated. Just wouldn't be necessary. I've pulled a fair number of rusty carbon steel bolts attaching stainless hangers...never noticed pitting of the hanger, or, what I'd think was excessive corrosion that might be attributed to a galvanic situation. Maybe in more humid climates? Plus, I've always wondered about the surface area difference between the metals as a player in the rate of corrosion. Big sheet of stainless steel with a couple of small carbon steel fasteners? Yeah, that'd be bad. Stainless hanger versus carbon steel bolt? Hmmm. Not sure. Not as big of a surface area difference. Given that most fasteners are zinc plated, when the zinc sacrifices itself, I'd imagine that effects the potential of a galvanic cell. I'm all for not mixing metals especially for fixed anchors in climbing. Especially aluminum hangers and steel bolts. But, plated carbon steel and stainless? I'm just not convinced is a huge deal. There's gobs and gobs of stainless hangers and carbon steel bolts/studs out there...

Sorry if I came across a bit strong Brian, I didn't mean to. In a dry climate like UT you won't see pitting in the hanger. In fact, none of the pictures you posted appear to be galvanic corrosion at all, just uniform corrosion of the non-stainless bolt. My experience doesn't come from galvanic corrosion of bolts and hangers, but from aircraft, and I can tell you for certain that when extensive galvanic corrosion occurs it leaves behind a pitted surface on the cathode. In bolts and hangers you would have to be in a very wet environment to find this issue.

I do agree that plated carbon steel and stainless steel mixed bolt/hanger combinations in a dry environment like the UT are really not a big deal and you would be hard pressed to find any bolt that exhibits galvanic corrosion in this environment. I've personally placed plenty of plated power bolts with stainless hangers, I don't do it anymore, but that's more just to avoid having to replace the bolts due to uniform corrosion rather than to avoid galvanic corrosion.

highaltitudeflatulentexpulsion wrote: It's common everywhere and I absolutely agree with you. That's the whole point of my post. Since it wouldn't weaken anything, why not. It could prevent metal on metal. If the gasket on the drain plug of my vehicle only cracks about once every 20 years, I think a silicone washer would hold up just fine.

There is nothing wrong with metal on metal... if you aren't already using all SS and are worried about galvanic corrosion you should be using plated hangers instead of SS. The drain plug on your car isn't getting 10KN of force applied to it, and unlike the drain plug on your car this bolt isn't for holding a liquid in so there is no need for any plastic washer. Washers on climbing bolts aren't gaskets or locking washers, they are simply there to distribute the force more evenly. When using a hanger that accommodates the included SS washer I will leave it on, with Climb Tech hangers (where the hanger does not sit flush with the washer) you must remove the washer or risk damage or failure of the hanger.