How long for electrolysis to eat through copper pipe?

anniel89February 7, 2006

I accidentally used a metal strap to secure a coppper pipe to the wall. Now it's behind drywall. How long will it take for electrolysis to corrode the copper pipe? Will it only effect where the metal is touching or will the whole line be affected?

Thank you in advance.

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It will affect the local area. Look on Google and read about galvanic reaction. I wouldn't lose sleep over it.

    Bookmark   February 7, 2006 at 5:57AM
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It may not do anything. For electrolysis to occur at a level you would need to be concerned about, there would have to be a lot of moisture between the strap and the pipe continuously so that there is electron transfer at the molecular level. Usually where you worry about electrolysis is if you connect copper pipe directly to galvanized, because the water flowing inside the pipes provides a route for the electrolysis. Last year I replaced a connection in my house that was a direct copper-galvanized joint without a dielectric insulator. It had been like this for about 25 years; there was some slight accumulation of deposits when I took it apart, but nothing that was impeding flow or causing a hole. I've also seen steel grounding clamps on copper pipe that had been there for decades, with no evidence of a problem (these were inside, and not exposed to rain). I'm going to suggest that your installation will probably not be an issue in your lifetime...

    Bookmark   February 7, 2006 at 6:12AM
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I also considered that steel boilers are hooked up with galvanized parts connected to copper pipe often and never noticed any problems. My scope is limited and maybe the hot water has something to do with it. My parents house have cold water fittings like this in their 80 year old house that never caused trouble.

    Bookmark   February 7, 2006 at 11:21AM
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Electrolysis is affected by water conditions that can cause a catalytic action. Sometimes, you will see that the Cu/Fe joint is not leaking but has another metal, calcium, oozing out of it. ThatÂs a sure sign that some kind of galvanic action has been occurring over long time.


    Bookmark   February 7, 2006 at 11:58AM
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"I also considered that steel boilers are hooked up with galvanized parts connected to copper pipe often and never noticed any problems."

Sealed hydronic systems rarely have galvanic issues. The ions in the water are 'getered' by corrosion, and then the entire process comes to a halt. Without an electrolyte galvanic corrosion cannot occur.

    Bookmark   February 9, 2006 at 8:59PM
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The same problems do occur on heating boilers and when connecting copper directly to iron pipe or boiler vessels they are required to use dielectric couplings. Normally the transition is made at a bronze valve.

    Bookmark   February 9, 2006 at 9:58PM
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My current house had steel straps on the copper pipe. 15 years old. The straps were all rusty, but there was no visible damage to the outside of the pipes.

    Bookmark   February 10, 2006 at 3:43AM
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The bronze requirement for heating systems is actually relatively new. For many years the connections have been made with copper directly into cast iron with no problems (I do not recall a lot of bronze connnectors on coal furnaces).
Cooper to cast iron works well until some fool starts draining the system every few months (or even annualy) to put 'clean' water in instead of the slightly oily, stinky stuff.

    Bookmark   February 10, 2006 at 9:30PM
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My house is over 30 years old. The water pipe connections on the outside of the house are copper (inside the house)to galvanized iron (outside the house) to bronze on/off valves. I just replaced one connection of galvanized iron pipe to a bronze on/off valve. The male thread on the galvanized iron pipe was 2/3 disintegrated inside the bronze on/off valve. My cncern is that there is a ticking time bomb for the other connections.

    Bookmark   November 6, 2006 at 6:43PM
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A steel strap on a supply line is not going to do anything.
You need water to set up the reaction, and if you have water on the outside of a supply line you have a bigger problem than a steel strap to deal with.

    Bookmark   November 8, 2006 at 9:28AM
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Most copper tubing straps are made out of steel, they look like copper, but that is just a coating. Don't fret it, the odds of having a problem are about the same as winning the lotto. Lots of luck.

"If all else fails, read the directons"

    Bookmark   November 8, 2006 at 11:26AM
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It would appear that some of the aforesaid posts are mixing apples and oranges. While it is true that electrolosys will always produce corrosion it is also true that not all corrosion is a result of electrolosys.

Under ordinaary circumstances electrolosys occurs inside the pipe wall at the point of a ferrous metal to non-ferrous metal connection I.E. iron pipe or vessel to copper pipe or fitting.

The effects of electrolosys only occur at the actual point of contact and it will have absolutely no influence on the service life of other pipe, fittings or components of your piping system.

While nothing is truely permanents, the intent of the building codes is to construct a structure with an anticipated life of 50 to 100 years. With that thought in mind it becomes necessary for the codes to address known problems in the worst case scenario. For that reason the codes define that we must use galvanized hangers or strapping on iron pipe, copper or copper clad hangers or strapping on copper pipe and plastic hangers or strapping on plastic pipe.

In the case of plastic piping the concern is that all pipes will undergo a certain amount of movement or vibration and over the course of time the use of metal hangers or strapping can cut into the pipe wall.

As Brickeye has already pointed out, there must be water present at the point of contact for electrolosys to occur. With this in mind the code requires that we use copper or copper clad strapping on copper pipe because there is a potential that "Condensate moisture" may occur on the outside of the pipe wall on a cold water line.

In actual practice, even in the worst csse scenario where the condensate moisture occurs since the point of contact is on the outside of the pipe it is also exposed to a constant source of oxygen from the atmosphere and the presence of moisture will enhance the formation of iron-oxide (rust) on the steel strapping. The effects of iron-oxide occur much quicker than what electrolosys would occur and the end result is that the stap hangers will rust through and break, rendering the hanger ineffective.

In regards to the original question about a galvanized iron strap on a copper pipe inside the wall, based upon what I have seen in my experience I would feel confident that you have absolutely no cause for concern.

    Bookmark   November 8, 2006 at 12:04PM
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outdoors: If you have galve. pipe in your system thats your ticking bomb, its worn out, your prob. is not electrolysis, you got to get the galve. out or plan to run into constant problems. Sorry for a negative, but lots of luck.

"If all else fails, read the directions"

    Bookmark   November 9, 2006 at 10:15AM
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We have 33 year old copper water pipes and have well water but the water does not contain 'bad stuff'. We have had the water tested. However, soil and water in our region are very acidic. Great for tomatoes but not copper apparently. We are getting more and more pin hole leaks in the pipes. We know the pipes are old but we were told that the low PH can also cause pin holes. A water filter company told me that dielectric problem could be doing this too and below is what they said. Anyone agree..comments?



I have found that the pin hole problem is caused by the grounding strap on the incoming water line. If you have a dielectric problem it will cause the holes in the copper piping. Remove the strap if you have it on the water line and have them drive a grounding rod into the ground to connect the ground from the breaker box.

    Bookmark   July 2, 2007 at 8:59AM
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Whether or not a copper pipe is grounded will have absolutely no effect on electrolosys.

Electrolosys is an electrochemical reaction that takes place at a molecular level solely at the point of contact between two dissimilar metals. It does not generate a current through the pipe and it has absolutely nothing to do with any stray electric current that might be flowing through the piping.

    Bookmark   July 2, 2007 at 10:08AM
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House power is AC and would have no effect on electrolysis.
If you have a water pipe 10 feet or more long in contact with the earth you are REQUIRED to use it as part of the houses grounding electrode system.
A second made electrode must also be used.

    Bookmark   July 2, 2007 at 3:41PM
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tbenton - What are the results from your water test? Who performed the tests? Was it a certified lab or just some guy with a little test kit? When you say there is no "bad stuff" in your water that is very vague and not nearly enough information to help.

Your water filter guy has no clue whatsoever. He apparently has just enough information to be dangerous, but not enough to help. Find somebody else to help and by all means, DON'T disconnect your grounding strap on the word of a 'filter guy.'

Are the leaks throughout the house or localized? Are in underground or above ground pipe? When you say the water is very acidic, do you have a pH?

Many different things can cause copper corrosion: low pH, high pH in conjunction with low organic matter, elevated chlorides, free chlorine, elevated sulfates, dissolved aluminum, high organic content in soils, or the water could just be really clean and therefore more aggressive. The first step is a good water test.

    Bookmark   July 3, 2007 at 2:12PM
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