Thread: What causes this

I ran into this a few days back and wondered how many have come across this and what is the cause.

Cleaning chemicals, high humidity with caustic fumes. If the water heater is gas check to see if there is a down draft the exhaust fumes can do that to the copper pipes.

How does the hot and cold pipes look?

I've seen it when people have stored corrosives nearby.

Swimming pool shock (chlorine) will do it also.

rick

Originally Posted by Rick Hurst

I've seen it when people have stored corrosives nearby.

Swimming pool shock (chlorine) will do it also.

rick

Definitely chemical related -- Something with a high alkalinity content.

Likely a cleaning product or fertilizer containing phosphates.

Maybe Chinese Drywall ?

Ummm, where to start?

First that's an ELECTRIC water heater (you don't even have to blow up the picture you posted to read "ELECTRIC WATER HEATER" in black between the red words "WARNING and CAUTION" on the label just below the data plate (label).

Next, the photo doesn't really show us clearly just what that copper tube or pipe is doing. Not looking up details on a 50 gal Ruud Electric "pacemaker" to find out if the TPRV comes out the top, or if that's a recirculation line.

Now, as to some having claimed it must be caustic (high pH/alkaline); not necessarily. Acids can do the same thing. As far as "Chinese Drywall" the usual condition seen is a blackening not greening on copper.

That is oxidation (the green) of the copper.

Some potential contributing causes:

Flux. The pipe and joints may have been wiped, but not cleaned, or flowed from heating, spreading the excessive flux paste all over the exterior (downward), sticky as it is, it can continue to etch and eat away at the copper. Pipe may not have been 'clean' to begin with.

Leak of refrigerants (such as in AC coils, refrigerators, freezers, auto AC units).

Exposure to other chemicals. Acids (low pH) OR caustics (higher pH) either or both can be factors. Common culprits if, for example located near laundry are: laundry amonnia, "oxy-clean" and similar "oxygen bleaches" such as Clorox II, etc. Laundry Chlorine Bleach (and/or direct exposure to a solution) which btw also contains Lye (a caustic) which remains as a residue. Various other cleaning products and other wall finishing products, etc. residue may not have been neutralized and/or flushed/rinsed clean.

Contact with moisture (humidity/condensation/flowing water) plus "air" plus a dissimilar metal - such as failure to use a compatable connection between the steel water heater tank and the copper plumbing.

Contact with moisture plus air plus concrete or masonry.

Contact with objectional current (may be AC or DC). i.e. improper bonding/grounding, and/or less than sufficient system electrode(s).

Is there a recirculation pump, water treatment, filter, etc. present in the system (unjumpered/bonded over)? Batteries stored or employed nearby? (leaky sump pump backup battery for example?).

What is the status/condition/type of the sacrifical anode? What isolation material was used to join the copper plumbing to the steel vessle? Exhausted dissimilar metals in the system, such as zinc (galv), steel, wrong valves employed, or high zinc content valves? Any "floating grounds" from older electrical work?

Unknown things that can be explored, besides cleaning the copper include: Check equipment ground and bonding; Check copper pipe for bonding, verify electrical connections, and elements for "leakage current". Verify grounding electrode system connections undamaged. Verify service bond, and check other systems bonding such as CATV, TelCo, etc. Verify gas pipe bonding, and isolation from GasUtility metallic pipe and meter (house side) isolation from cathodic protection (DC) current.

Well the picture is not clear enough on my little screen to see the blurred writing on water heater. Also I just said if it was a gas heater it could be due to exhaust gasses.

Originally Posted by Ron Hasil

Well the picture is not clear enough on my little screen to see the blurred writing on water heater. Also I just said if it was a gas heater it could be due to exhaust gasses.

exhaust gasses, unvented, spillage or backdraft, can be from other appliances still causing problems. I dunno, the big fat UL listing insignia on the data plate is pretty clear to me.

Some fun reading:

Copper Pipe Turns Green - Mike Holt's Forum (Copper pipe turns green - discussion)

Copper Corrosion, Copper Pipe Corrosion Prevention and Control (Copper pipe corrosion subject page with links, corrosionist.com)

Why Does Copper Turn Green? (Why does copper turn green, also from corrosionist.com)

http://www.fwr.org/copper.pdf (Causes of Copper Pipe Corrosion in Plumbing Systems, A review of current knowledge, 2003, revised September 2010, Foundation for Water Research; pdf file copy also attached).

The times I've seen it, there was opened fertilizer in the same confined space as the water heater ... but those water heaters also showed rust along the steel edges, and I don't see any in that photo.

Still, 'something environmental' would be my guess.

I have seen gas water heaters with the UL logo on them. The power vent heaters have electric controls as well as gas controls. So just seeing a UL logo on a label is not enough for me to assume its just an electric water heater.

R.H.,True, but the LISTED above and the device it is listed as below, are pretty clear to read, to me.There's no mistaking it, UL uses other symbols and markings when they're listing a gas fired device. Heck, I can read the data plate, as-is in the post, don't even have to blow it up, just expand the browser to full screen mode. Its an electric, its as plain as the nose on your face in your profile icon. I really don't know why this has turned into some sort of argument or something. It's clearly an electric water heater.

Originally Posted by Ron Hasil

Cleaning chemicals, high humidity with caustic fumes. If the water heater is gas check to see if there is a down draft the exhaust fumes can do that to the copper pipes.

Thanks, Ron. That is good general info. I for one appreciate your knowledgeable input here.

Originally Posted by Ron Hasil

Well the picture is not clear enough on my little screen to see the blurred writing on water heater. Also I just said if it was a gas heater it could be due to exhaust gasses.

This also seems to be pretty clear. If somebody says they couldn't read it, they couldn't read it.

http://www.fwr.org/copper.pdf (Causes of Copper Pipe Corrosion in Plumbing Systems, A review of current knowledge, 2003, revised September 2010, Foundation for Water Research; pdf file copy also attached)

That was a good read -- Thanks.

Also; The T&P on all of the tanks in the PaceMaker series is always located on the top of the tank -- This makes the series very popular in multi-unit apartment buildings and condominiums where ease of access in confined spaces is desired.

If it was due to stored chemicals or aerosolized chemicals, I would expect to see blotching but not a unilateral coating as this is. No, I think this is due to the installer wiping the pipes down with acid flux to shine them up but not rinsing.

Originally Posted by Bob Harper

If it was due to stored chemicals or aerosolized chemicals, I would expect to see blotching but not a unilateral coating as this is. No, I think this is due to the installer wiping the pipes down with acid flux to shine them up but not rinsing.

I agree flux not cleaned off but spread is the most likely, which is why I listed it first; although I've seen the same when a HO "cleaned" the area with out neutralizing as well, especially if later exposed to high concentrations of a contributor, such as in a humid laundry environment, when open "soaking" of stained items, or post-flood cleanup.

Corrosion inhibitor exhausted antifreeze too.

Ah Thanks A.G. Watson. I don't see Chinese drywall in this area,at least not yet,but I'll keep an eye open for blackening.