Thread: What causes this ? See photo

What causes this type of corrosion on a bronze water heater supply vavle body ? See photo. I see it quite often and understand galvanic action when two disimilar metals are in contact, like copper and steel, but when I see this type of corrosion is usually takes on this same form and it is usually only on the bronze body of the valve, not where the valve comes in contact with another metal. I have heard several opinions and one is when corrosion causes a pin-hole leak and then the corrosion sort of "heals" the hold by corroding over the hole. Comments appreciated.

Thanks

Gene

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Its from an electrolysis condition with the pipes as you stated.

Exactly what is the cause you would need to look into all the pipe connection.

That my best poke at it.

Best

Ton

Originally Posted by Gene South

What causes this type of corrosion on a bronze water heater supply vavle body ? See photo. I see it quite often and understand galvanic action when two disimilar metals are in contact, like copper and steel, but when I see this type of corrosion is usually takes on this same form and it is usually only on the bronze body of the valve, not where the valve comes in contact with another metal. I have heard several opinions and one is when corrosion causes a pin-hole leak and then the corrosion sort of "heals" the hold by corroding over the hole. Comments appreciated.

Gene,

I would guess pinholes as well, but I could not say for sure. Have you tried emailing your photo to the manufacturer?

Hello Gunnar, no I have not sent a photo to the manufactor. I probably have seen this on no less than 100 bronze suppy valve bodies in the past year with this specific type of corrosion. Here in North Texas our water has a high mineral content. If others are not seeing this corrosion, I am wondering that in addition to hydrolysis action, possibly the water in our area may be a contributing factor...

Originally Posted by Gene South

Hello Gunnar, no I have not sent a photo to the manufactor. I probably have seen this on no less than 100 bronze suppy valve bodies in the past year with this specific type of corrosion. Here in North Texas our water has a high mineral content. If others are not seeing this corrosion, I am wondering that in addition to hydrolysis action, possibly the water in our area may be a contributing factor...

Gene,

You may have hit on it. I don't think I have ever seen this before, so it might be your water quality. Unless it is a run of defective valves that was only sent to TX (unlikely). Maybe some of the other TX inspectors will chime in.

Gene,

I see way too many of them myself.

rick

Originally Posted by Gene South

What causes this type of corrosion on a bronze water heater supply vavle body ?

Originally Posted by Gunnar Alquist

I would guess pinholes

Leaks are causing that.

The cause of the leaks could be the water, or defective casting of the valve.

No dissimilar metal in that photo: copper-to-brass-to-copper is okay.

Since I and a lot of other North Texas inspectors are seeing this and it appears inspectors in other areas are not,,....it makes me wonder about the affect of the water on the metal. Not sure. Possibly a bad batch of castings but that seems more unlikely to me. Probably need to hear from more inspectors to get a better perspective.

Originally Posted by Gene South

Since I and a lot of other North Texas inspectors are seeing this and it appears inspectors in other areas are not,

I'm not from Texas and I used to see it all the time.

It's Metalic Herpes

I am a Heavy Duty Truck mechanic and it looks just like what you get when you repair a copper radiator core with acid core solder. could acid core solder been used to sweat this valve in?

Michael, I do not know if acid core solder was used but I appreciate your insight. I am sort of intrigued to try to find out how and what the root cause is. Maybe you are right.

Thanks

Gene

Michael, I do not know if acid core solder was used but I appreciate your insight. I am sort of intrigued to try to find out how and what the root cause is. Maybe you are right.

Thanks

Gene

Quick Google search turned up this Dezincification of a brass valve Dezincification Dezincification selectively removes zinc from the alloy, leaving behind a porous, copper-rich structure that has little mechanical strength. An in-service valve suffering from dezincification has a white powdery substance or mineral stains on its exterior surface. The valve may exhibit water weeping from the valve body or stem/bonnet seal. Why Dezincification Occurs Copper-zinc alloys containing more than 15% zinc are susceptible to dezincification. Zinc is a highly reactive metal, as seen in its galvanic series ranking. This reactivity stems from the fact that zinc has a very weak atomic bond relative to other metals. Simply, zinc atoms are easily given up to solutions with certain aggressive characteristics. During dezincification, the more active zinc is selectively removed from the brass, leaving behind a weak deposit of the porous, more noble copper-rich metal. Conditions favoring dezincification are contact with slightly acid or alkaline water. Not highly aerated, low rates of flow of the circulating liquid, relatively high tube-wall temperatures and permeable deposits or coatings over the tube surface. While I have never considered the Dallas area water particularly "hard" there is no doubt that all area surface water is very alkaline. Almost all of the contributing factors listed are present at valves on top of water heaters here. Alkaline water, not highly aerated, low rates of flow (at least 90% of the day is at low or no flow in most households), high tube wall tempertures.

Sorry my post is so hard to read, the format functions don't work. Any ideas?

formatting?

Seems to work fine with internet explorer, just not with FireFox

Agreed it's a leak of the smallest kind in that case through the porosity of the bronze. I just did a repair on a 45 year old sweat joint that had a corrosion build up on it due to a poor sweat connection. For 30 years there was simply corrosion recently it just started to drip about 1 drop an hour.

I think Jim nailed it. Iv'e seen this also in my area.

I would agree. It is a water problem. I rarely see pitting that serious in south-west Michigan, but on occasion it is present.

Jim, yes, this is it. And North Texas water fits the definition of hard water. The calcificaition on the kitchen sink spouts we see is one indicator.

Thanks

Gene

So then, are you suggesting that an oxymoron caused this corrosion?

It is caused by a natural porosity (pin holes) that is inherent with castings, particularly sand castings, which is what your valve appears to be. You won't see this with a forged product. A manufacturer could avoid this by having the machined castings electroless nickel plated prior to final assembly, but alas, that is an additional cost. I recognized it immediately when I started seeing it while conducting home inspections. (I used to work for a manufacturer of various pressure regulators in a prior life, and the sand castings we used for helium regulators dealt us a fit until we came up with this solution.)

I explain what it is to the clients, and tell them that once the valve has sealed itself with the minerals in the water (what appears to be corrosion), that they probably won't have any further problems with it - but that they should monitor it for change anyway, just in case. And, if it would continue to "corrode", they'll probably have to get it replaced with a better quality valve. (Actually, I'm guessing that if the appearance bothered a person, you could probably wire brush it back to shiny, and it would probably stay that way once the pores have gotten plugged up.)

(By the way, this posting was done, and edited in Firefox!)

Originally Posted by Michael Chambers

It is caused by a natural porosity (pin holes) that is inherent with castings, particularly sand castings, which is what your valve appears to be. You won't see this with a forged product. A manufacturer could avoid this by having the machined castings electroless nickel plated prior to final assembly, but alas, that is an additional cost. I recognized it immediately when I started seeing it while conducting home inspections. (I used to work for a manufacturer of various pressure regulators in a prior life, and the sand castings we used for helium regulators dealt us a fit until we came up with this solution.)

I explain what it is to the clients, and tell them that once the valve has sealed itself with the minerals in the water (what appears to be corrosion), that they probably won't have any further problems with it - but that they should monitor it for change anyway, just in case. And, if it would continue to "corrode", they'll probably have to get it replaced with a better quality valve. (Actually, I'm guessing that if the appearance bothered a person, you could probably wire brush it back to shiny, and it would probably stay that way once the pores have gotten plugged up.)

(By the way, this posting was done, and edited in Firefox!)

MC: Good info. Thanks.

In the second picture of the original post, it appears that where the relief valve should have been installed, that it has been plugged!

I see this all the time here in the Phoenix area. I would have to go back and find the source of my memory but I had understood it to be poor quality gate valves manufactured in China (kinda like the Chinese drywall issue). Thats what I have been telling my clients for years. If its not leaking or frozen I do not comment on it unless my clients asks.

I rub my fingers over a large blister on the valve and if my finger is wet/damp I write it up as a leaking valve and recommend replacement with a ball valve. I frequently find the valves in this condition frozen in the on position and again write it up as frozen as its corroding internally as well.

Originally Posted by Michael Chambers

I explain what it is to the clients, and tell them that once the valve has sealed itself with the minerals in the water (what appears to be corrosion), that they probably won't have any further problems with it - but that they should monitor it for change anyway, just in case. And, if it would continue to "corrode", they'll probably have to get it replaced with a better quality valve.

So, based on the above, if there is a leak in a heat exchanger which seals itself when it cools down, there is no need to replace the heat exchanger?

The valve leaks, that is why that crap is on the OUTSIDE of the valve, replace the friggin' valve!

What is so dang difficult about writing that up.

Yes, all the information about the causes is good (such as the Dezincification), but you write it up as defective anyway.

Regarding the pin holes from the manufacturer of the valve and that being okay - that is pure crap as the valve is required to be water tight and not have any pin holes in it.

Jerry, I know we are back to one of your favorite subjects, being explicit in calling for repairs, not upgrade, not monitor, etc. But that is part of the problem here, the valve may or may not be leaking depending on the theory. There is corrosion on the valve but does that mean that water is leaking and the valve is defective?
Just because there is rust on a widget, does that mean the widget needs to be replaced right now or 25 years from now when the doo hicky the widget is connected to is replaced?

Back to the specifics of the valves in question, seems like they are just cheap valves that are prone to corrosion.

Originally Posted by Jerry Peck

So, based on the above, if there is a leak in a heat exchanger which seals itself when it cools down, there is no need to replace the heat exchanger?

The valve leaks, that is why that crap is on the OUTSIDE of the valve, replace the friggin' valve!

What is so dang difficult about writing that up.

Yes, all the information about the causes is good (such as the Dezincification), but you write it up as defective anyway.

Regarding the pin holes from the manufacturer of the valve and that being okay - that is pure crap as the valve is required to be water tight and not have any pin holes in it.

Jerry;

1. If you will check back to the top of this thread, you will discover that the original question was; "What causes this type of corrosion ........? With that sole question in mind, I was very happy to be able to offer the benefit of unique experience and knowledge that I have, that you and the others might find useful. I am fairly new to the world of home inspections, I've been learning from all of you on this forum, and I jumped at the chance to reciprocate for once.

2. A once porous water valve, that may have sealed itself 20 years ago, and is now doing its job as it should, cannot reasonably be compared to a cracked heat exchanger that might be in eminent danger of killing someone.

3. If the valve has indeed sealed itself up (as they usually do fairly quickly, and it appears this one probably has), and if it is consequently no longer leaking (only Gene can tell us that), replacing it just because it has some mineral deposit on the outside is a needless waste of money. I certainly would not worry about it if it were in my house. I would keep an eye on it, but I know that it is probably not a problem. I would however, probably replace it the next time the water heater needed to be replaced. Obviously, even for me, if it is still leaking, it would of course need to be replaced right away.

4. I've checked again to make sure, and nowhere in my posting did I say that I would not write these up. You are making that assumption. For the record, it appears in my report as; "...what appears to be a once porous water heater inlet valve that appears to have sealed itself up. Monitor for change, and if any leaking or further deterioration occurs, recommend further evaluation and probable replacement by a qualified plumbing contractor."

Originally Posted by Jim Luttrall

Jerry, I know we are back to one of your favorite subjects, being explicit in calling for repairs, not upgrade, not monitor, etc. But that is part of the problem here, the valve may or may not be leaking depending on the theory.

Jim,

Quite incorrect.

That valve is leaking, plain and simple. That IS what caused those deposits to form.

What is "theory" is what caused the valve to leak ... but leaking it was and is - unless you can keep a straight face while telling your client that the siding was loose, but you put some bubble gum behind it, the gum dried up and it is no longer loose.

There is corrosion on the valve but does that mean that water is leaking and the valve is defective?

It does mean that.

The water which caused the corrosion did not come from outside the valve, it came from inside the valve. The only way for that water to come from inside the valve is because the valve was ... leaking.

Just because there is rust on a widget, does that mean the widget needs to be replaced right now or 25 years from now when the doo hicky the widget is connected to is replaced?

Jim, let's make the correct comparison: You have an air handler unit in an attic with an auxiliary drain pan under it. There are barnacles UNDER the drain pan growing from the BOTTOM of the drain pan.

Is that drain pan "leaking" or would you say "there is rust on" that "widget"?

Here is another one: Cast iron drain lines covered with barnacles ... leaking or not leaking?

Back to the specifics of the valves in question, seems like they are just cheap valves that are prone to corrosion.

Maybe not cheap valves, maybe it was the water.

Either way (cheap valves or the water) that valve IS LEAKING ... and needs to be REPLACED.

Originally Posted by Michael Chambers

1. If you will check back to the top of this thread, you will discover that the original question was; "What causes this type of corrosion ........? With that sole question in mind, I was very happy to be able to offer the benefit of unique experience and knowledge that I have, that you and the others might find useful. I am fairly new to the world of home inspections, I've been learning from all of you on this forum, and I jumped at the chance to reciprocate for once.

Michael,

And, as stated, your information was very good.

However, the discussion THEN turned away from that and about the valve and whether or not it was leaking, and whether or not it needed to be replaced, with someone saying that, no, it did not need to be replaced because it TEMPORARILY (although that person did not use that word) SEALED ITSELF.

That is not a run-flat tires which seals itself, that is a plumbing component which is REQUIRED to be made not only water tight but to withstand a minimum pressure at a minimum temperature.

2. A once porous water valve, that may have sealed itself 20 years ago, and is now doing its job as it should,

Quite incorrect.

The valve was NOT designed to be a self sealing valve, it was, in fact, designed NOT TO LEAK, and it did, and is.

3. If the valve has indeed sealed itself up (as they usually do fairly quickly, and it appears this one probably has), and if it is consequently no longer leaking (only Gene can tell us that), replacing it just because it has some mineral deposit on the outside is a needless waste of money.

And that money IS NOT the concern of the home inspector, that MONEY is the concern of the seller and the buyer, with the home inspector's concern only being to report that the valve IS DEFECTIVE ... as it was never intended to leak, and once leaked the only corrective action is replacement.

Originally Posted by Jerry Peck

Quite incorrect.

That is your opinion. I don't agree. I've seen a number of valves like this, and have examined each one very carefully because of the obvious evidence. I have yet to see one that is still leaking. Yes, when installed it did leak and was defective. Yes, it is still defective, but it is not leaking anymore. What I don't agree with is your contention that because it did leak, probably for a short period of time, possibly several years back, I should tell the client that is HAS to immediately be replaced.

I put it in the same category as the seldom used main water service valve in the basement. If you ever have to use it, expect it to possibly drip for a couple of days, then it will usually stop. It doesn't mean that one has to immediately call in a plumber. It just means you should keep an eye on it for a while. If it stops like they normally do, life is good. If it keeps on dripping, then yes, get a plumber in to tighten up the gland nut or add some more packing. As I think you will agree, just report the facts, give the client their options, and then let them decide how they want to prioritize it.

Originally Posted by Jerry Peck

And that money IS NOT the concern of the home inspector, that MONEY is the concern of the seller and the buyer, with the home inspector's concern only being to report that the valve IS DEFECTIVE ... as it was never intended to leak, and once leaked the only corrective action is replacement.

I agree with the first part of that statement, but not the last part, for reasons stated above. When I said that replacing a valve that is not leaking is a needless waste of money, I was giving you my own opinion, not telling you what I would tell my client. I give them the facts, let them know their options (and possible consequences), and let them make the decision as to what to do.

Originally Posted by Michael Chambers

That is your opinion. I don't agree. I've seen a number of valves like this, and have examined each one very carefully because of the obvious evidence. I have yet to see one that is still leaking. Yes, when installed it did leak and was defective. Yes, it is still defective, but it is not leaking anymore.

It is STILL leaking.

Scrape off those deposits and you will find that out in short order, oh, by the way, when you scrape those off, you will want to test the valve at its design pressure to verify that it is 'not leaking' as you say.

However, now that you have acknowledged that the valve *IS* *DEFECTIVE* ... why would you not write it up, and why would you search your mind for whatever "justification" you can think up trying to call it "not leaking", you just said it was "defective", which means it needs to be "replaced".

You are a dick!!

Originally Posted by Rich Schaefer

You are a dick!!

Rich,

Very profound statement you made there.

Took great intelligence and soul searching to come up with something that deep.

One can lead a horse to water, but sometimes the horse refuses to drink and ends up drowning.

It does appear that you may have gone in over your head and drowned.

Originally Posted by Rich Schaefer

You are a dick!!

WHAT!
Grow up.

Originally Posted by Jerry Peck

Rich,

Very profound statement you made there.

Took great intelligence and soul searching to come up with something that deep.

One can lead a horse to water, but sometimes the horse refuses to drink and ends up drowning.

It does appear that you may have gone in over your head and drowned.

JP: Maybe he meant:

Distinguished Inspector Counseling Kooks

Wear it like a badge . . .

If I find corrosion on any water line and or fitting/valve I write it up. Cannot be anymore direct in telling folks that you have no idea whether or not the corrosion will continue and the pipe/fitting fail.

Not sure what all the hub bub is. Corrosion of anykind on pipes and or fittings/valves the chance is it will continue. Chnace is if you do not think so....Chance is you will be wrong.

I think it is better to be right about the corrosion more than likely continuing instead of the possibility that it *may* not continue.

Yeah think ??????????????????????

Originally Posted by Michael Chambers

(Emphasis is mine.)
4. I've checked again to make sure, and nowhere in my posting did I say that I would not write these up. You are making that assumption. For the record, it appears in my report as; "...what appears to be a once porous water heater inlet valve that appears to have sealed itself up. Monitor for change, and if any leaking or further deterioration occurs, recommend further evaluation and probable replacement by a qualified plumbing contractor."

If I were to make an assumption from your posting, I would wonder why you would ever advise your clients to scrape those mineral deposits off. My advice to my clients is to not mess with the mineral deposits unless they're going to replace the valve anyway.

Actually, I've never tried to take any of those deposits off to see what would happen. Knowing how they occur however, I'm thinking that you could take them off, and the valve would not leak. Now I'm making an assumption (apologies ahead of time) when I suggest that you might be thinking of them as being like the rust barnacles on a plumbing stack pipe. Those however, are the result of the cast iron pipes corroding through from the inside, and there is pretty much no structure left under the barnacle.

The water valves are starting out with some amount of porosity due to a series of pin holes from the casting process. After they're put into actual use, the pin holes get clogged up, and then stop leaking. If they've been clogged up well enough, taking the exterior deposits off may not cause them to leak at all - because the full thickness of bronze or other metal is still there under the deposit.

I'll have to try taking the deposit off of one sometime just to see what happens. I would predict however, that if they would start leaking again, they would again stop leaking in fairly short order - the same way they did the first time. I think I'll still continue to report the facts to my clients, give them their options, and let them make the decision as to the urgency of the situation.

It's been nice dancing with you!

Just wondering if the grounding clamp in the first set of photos, and in the one Rick posted might be part of what caused the corrosion.

Also wondering if the corrosion might be external, chemicals reacting to burnt gas, or clinging to an occasional sweating valve. Were any stored in the room? Some water heater companys void their warranty if they are.

Could be a leak tho.

I really like the dezincification theory, I'M, going to borrow that if I may, company Christmas party around the corner and all.

So many choices...so many leaks

I have removed the corrosion only to have it return over a loooooooooooong period of time perhaps 6- 10 years. Well advised it is the porosity of the valve and microscopic leakage over time. I agree with Micheal,report the findings and let powers that be decide