Galvanic corrosion

[eds54]

Hi All
Has anybody had a problem or even heard of Galvanic Corrosion. A house that was completed 2 years ago has started having water leaks. (I know this is a site for electricians) a water softener was recently fitted and the manufacturers have suggested that because the plumber has used a mixture of copper and plastic pipe there is no earth continuity throughout the pipes and possibly causing Galvanic Corrosion where the 2 join. Has anybody had this problem before an if so was there a solution other than cross bonding across the joints which I imagine even if the plumber could remember where they were would be a nightmare. I have never heard of this happening before so any help would be appreciated.

 

[UKMeterman]

You're talking about creating electrolytic cells for galvanic corrosion, which would need two separate metals immersed....and a potential difference.
I can't see copper and plastic interacting in such a way.
Are any solutions having an affect on the copper?

Could have different metals with radiators, I suppose.....copper pipes, salty solution and a variance in potential. It would be a case of if it's metal....BOND IT.....back to 15th edition and earth cabling everywhere.:nonod:

The earth bonding wouldn't help, it would be like trying to short out a battery, even the DNOs have corrosion problems where two metals meet. The solution is on central heating is to use inhibitor, and on potable water to ensure dissimilar metals don't touch and clean out the flux.

 

[davesparks]

Galvanic corrosion is one of the many problems which plague land rovers, the aluminium body panels riveted to the steel framework combined with the inevitable water ingress results in white fluffy corrosion and rusting everywhere.

Green inside your pipe work sounds more like something attacking the pipe. Did the water clown setup the water softener correctly with testing of the pH etc? Maybe he didn't clean the flux and suchlike out of the pipe work properly?


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[davesparks]

If a softener was fitted first thing to do would be to get the water salt content and ph level tested.

If I may be pedantic for just a moment I think you might mean pH


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[Marvo]

If I may be pedantic for just a moment I think you might mean pH

Can I use the excuse that English is my second language?....Nah, thought not but it was after midnight here so the post could have been worse

 

[PEG]

Without a doubt,the most common cause of corrosion within CH systems,is a failure to properly purge and flush,after installation.

This can remain for years,through further improper flushing and reeks havoc.

Chemical analysis,although expensive,can confirm this.

Galvanic or electrolytic corrosion,can and does occur in CH systems,but it is between differing metals,on occasion increased by electrical influences,but self sustaining in an acidic environment.

...It seems that some tradesmen,have been completing installations improperly,and leaving the resulting problems to develop,and be attended to,by those who care......next to brexit,jeremit and englandit...it is the most shocking revelation encountered yet :joker:

 

[davesparks]

Can I use the excuse that English is my second language?....Nah, thought not but it was after midnight here so the post could have been worse

Normally you probably could, but I suspect that pH is somewhat of an international term, probably some SI or IUPAC thingummy

I don't think many people would even spot that one, but having written about pH and pOH at great length in A level chemistry lessons I really can't help myself now.

I can't for the life of me remember much more about it though, I think it's something like power of Hydrogen and power of Hydroxide.

Doesn't it relate to the concentration of H+ ions or OH- ions in a solution? Though it must inverse as stronger acids have lower pH


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[Marvo]

My dad is/was a professor of chemistry (retired) but I only took it in secondary school which was way too long ago to be useful now. I just know if water is acidic or alkali it causes pin ----- corrosion holes in copper pipes and water softeners can change the ph *ahem* or pH. They also increase the salt in the water although it's usually only to what are considered low levels but that can also accelerate corrosion. It would be easier and cheaper to test pH and salt levels and remedy if necessary before getting into sacrificial anode retrofits and extra bonding which probably wouldn't help if it's a water problem causing the corrosion. I've also seen copper with pin ----- holes at the joints which was caused by someone using the wrong type of flux in the soldered joints.

 

[ipf]

The earth bonding wouldn't help, it would be like trying to short out a battery, even the DNOs have corrosion problems where two metals meet. The solution is on central heating is to use inhibitor, and on potable water to ensure dissimilar metals don't touch and clean out the flux.

I agree, not in the slightest....only a reference to the 15th and bonding.

 

[Mark42]

I agree that the problem is most likely poor plumbing work. Are the leaks in the mains water pipework, or in a closed central heating system?

It could be the wrong flux used, or if central heating, not enough (or any?) inhibitor in the system.

Galvanic corrosion is very real (yup, I have a Land Rover too ), but only occurs where dissimilar metals are in contact in a wet environment. It's effectively making a battery - two plates and an electrolyte. It cannot occur in a metal to plastic joint.

For information, it's worth electricians having a tube of this stuff in the toolbox, for fitting stainless or ali boxes etc with steel screws:

https://www.amazon.co.uk/Duralac-Anti-Corrosive-Jointing-Compound/dp/B00LB6EUEO

I use it all the time. A lot cheaper than the ridiculously-expensive marine 'Tefgel'.