# Can anyone explain how this is dielectric?



## johnlewismcleod (Apr 6, 2012)

We replaced 400' of old galvanize water service with K copper the other day and the building engineer asked me how the dielectric transition fitting worked.

I realized I had never given it much thought before that point (hopefully I didn't look like a deer in the headlights when he asked me :laughing.

I said it must be the copper colored paint that neutralized the dielectric effect, but I was only guessing :whistling2:...anyone know what I should have said?


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## ChrisConnor (Dec 31, 2009)

You should have said "what kinda engineer asks such remedial questions?"


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## MarkToo (Dec 17, 2011)

That transition fitting your hand is on should be plastic lined. Same deal as HWT nipples.


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## johnlewismcleod (Apr 6, 2012)

MarkToo said:


> That transition fitting your hand is on should be plastic lined. Same deal as HWT nipples.


It is...but the victaulic couplings bridge the transition from one side to the other (just like WH nipples). I don't know what metal is used in the WH nipples, but I'm pretty sure the vic trans fittings are steel.


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## SPH (Nov 4, 2008)

For corrosion to occur there needs to be water. That plastic lined fitting prevents the dissimilar metals from meeting inside the piping.


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## eddiecalder (Jul 15, 2008)

SPH said:


> For corrosion to occur there needs to be water. That plastic lined fitting prevents the dissimilar metals from meeting inside the piping.


Winner :thumbup:


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## rocksteady (Oct 8, 2008)

SPH said:


> For corrosion to occur there needs to be water. That plastic lined fitting prevents the dissimilar metals from meeting inside the piping.


Then why do I spend more $$ on copper straps and clamps instead of buying galvinzed ones? 





Paul


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## eddiecalder (Jul 15, 2008)

rocksteady said:


> Then why do I spend more $$ on copper straps and clamps instead of buying galvinzed ones?
> 
> 
> 
> ...


The copper tubing is in contact with the water. If the copper was lined with plastic on the inside like on the CTS fitting it would not be required.


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## eddiecalder (Jul 15, 2008)

SPH said:


> For corrosion to occur there needs to be water. That plastic lined fitting prevents the dissimilar metals from meeting inside the piping.


What SPH implied was for corrosion to occur there needs to be "CONTACT" with water.


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## TX MECH PLUMBER (May 27, 2011)

I'm not understanding. I get water can carry electrolysis but I was taught that no metal should touch copper. No strap hanger metal stud clamp ect ect. That why we use mil rap or copper plated clamps. I have repaired leaks in copper from metal touching copper on the outside and formed a pin hole. One was a ceiling wire for suspended ceiling just touching the line. If the pipe has no water in at all and is dry would electrolysis still happen??


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## eddiecalder (Jul 15, 2008)

TX MECH PLUMBER said:


> I'm not understanding. I get water can carry electrolysis but I was taught that no metal should touch copper. No strap hanger metal stud clamp ect ect. That why we use mil rap or copper plated clamps. I have repaired leaks in copper from metal touching copper on the outside and formed a pin hole. One was a ceiling wire for suspended ceiling just touching the line. If the pipe has no water in at all and is dry would electrolysis still happen??[/
> 
> When plumbers talk about electrolysis we really mean galvanic corrosion. In order for galvanic action to take place we need two electrochemically dissimilar metals and a conductive path for the exchange of positive and negative ions. When the contact is broken the reaction will not take place.


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## eddiecalder (Jul 15, 2008)

Think of it as breaking the continuity. Two wires not connected infinite resistance ( this is what the CTS fitting is doing ). Once the water touches everything we have continuity (zero resistance)


I hope that makes sense.


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## UN1TED-WE-PLUMB (Oct 3, 2012)

What I don't get is why no dielectric on heat lines? I see copper threaded into black steel on heat lines all the time with no corrosion.


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## Don The Plumber (Feb 14, 2010)

Outside of copper water pipes will see water, in the form of condensation. :yes:


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## plbgbiz (Aug 27, 2010)

UN1TED-WE-PLUMB said:


> What I don't get is why no dielectric on heat lines? I see copper threaded into black steel on heat lines all the time with no corrosion.


Always puzzled me too. I think Oldschool answered that in a boiler thread a few months ago. I think it has something to do with it being a closed system but can't remember the science of it.


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## eddiecalder (Jul 15, 2008)

It is due to the oxygen in the water. Electrolysis, galvanization, and oxidation all need oxygen to take place.

I failed to mention that in my other posts.


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## PLUMBER_BILL (Oct 23, 2009)

rocksteady said:


> Then why do I spend more $$ on copper straps and clamps instead of buying galvinzed ones?
> 
> <snip>
> 
> Some inspectors require copper straps in lieu of plastic or Mickey Mouse type hangers. Here is what I've done -- bought 1/2" EMT one hole hangers [won't melt and break away on hot piping]. Went to Habor Freight and bought that insulator you can dip in [plier handles] diped the hangers in the liquid. [just the curve] Works good and you now have an insulated strap. Iv'e also used it to satisfy when running in Kindorf.


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## rocksteady (Oct 8, 2008)

I'm still not seeing how water vs. no water makes electrolysis/galvanic corrosion an issue. I'm sure a ton of us have repaired slab leaks due to a copper water line resting on a piece of rebar. I've seen copper water lines leak right at the point where they contact galvanized strapping or a bent over nail. Does it just take longer if the contact is outside of the pipe? I know there are varying moisture levels in the air. Does humidity qualify as a conductor for this sort of corrosion? 





Paul


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## justme (Jul 4, 2012)

water running through the pipe creates electrolysis ,then when the dissimilar metal is touching the copper pipe with water running through it you get a leak because of electrolysis at the point of contact .


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## rjbphd (Feb 5, 2010)

There are NO reason to have die electric union crap on properly installed hydronic system... just right now, I'm working on a system that's over 60 years old mixed with copper and black steel... no corrosion or leak .. 
If inspector want die electric crap on heating, ask and write down the liensce and tell him to hit the road..


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## TX MECH PLUMBER (May 27, 2011)

rjbphd said:


> There are NO reason to have die electric union crap on properly installed hydronic system... just right now, I'm working on a system that's over 60 years old mixed with copper and black steel... no corrosion or leak ..
> If inspector want die electric crap on heating, ask and write down the liensce and tell him to hit the road..


I do hydronic systems all the time and we always use dialect protection. Its in the specs!! Why do u think it doesn't need it but on domestic it does. Does it have to do with chemicals in the water. ?? Please explain. I want know all I can about this. Thanks rj


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## UN1TED-WE-PLUMB (Oct 3, 2012)

TX MECH PLUMBER said:


> I do hydronic systems all the time and we always use dialect protection. Its in the specs!! Why do u think it doesn't need it but on domestic it does. Does it have to do with chemicals in the water. ?? Please explain. I want know all I can about this. Thanks rj


Oldschool.... Your expertise is needed!!


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## rjbphd (Feb 5, 2010)

TX MECH PLUMBER said:


> I do hydronic systems all the time and we always use dialect protection. Its in the specs!! Why do u think it doesn't need it but on domestic it does. Does it have to do with chemicals in the water. ?? Please explain. I want know all I can about this. Thanks rj


 Electroyilles(sp) isn't there when using the same water over on the closed system... whomever wrote the specs doesn't know and never gotton their hands dirty... another guy that wrote a book about it is Dan Holohan.. 
Old School's input is vaulable too, after 8 pm fridays...


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## U666A (Dec 11, 2010)

Did no one think to check Victaulic?


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## UN1TED-WE-PLUMB (Oct 3, 2012)

U666A said:


> Did no one think to check Victaulic?


Ahh too much work:jester:


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## eddiecalder (Jul 15, 2008)

The water running in the pipe has friction. The friction causes a dc voltage between the two dissimilar metals. Just like dragging your feet in scold on a carpet and touching a door knob.


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## OldSchool (Jan 30, 2010)

eddiecalder said:


> The water running in the pipe has friction. The friction causes a dc voltage between the two dissimilar metals. Just like dragging your feet in scold on a carpet and touching a door knob.


^^^^^ 
?????


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## eddiecalder (Jul 15, 2008)

That was worded terribly. I'm at work sorry. I'll explains it in a way that is correct later.


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## eddiecalder (Jul 15, 2008)

Ok here is the best I can do 

People are using the terms Electrolysis and Galvanic corrosion interchangeably. They are different

Galvanic corrosion refers to corrosion damage induced when two dissimilar materials (one anode and one cathode) are coupled in a electrolyte (water). The less "noble" material will be corrode. Three things are needed for Galvanic action to occur.

1) Electrochemically dissimilar metals must be present
2) These metals must be in electrical contact, 
3) The metals must be exposed to an electrolyte 


Electrolysis is the separation of hydrogen and oxygen from water with a outside energy source (DC voltage)


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## johnlewismcleod (Apr 6, 2012)

eddiecalder said:


> Ok here is the best I can do
> 
> People are using the terms Electrolysis and Galvanic corrosion interchangeably. They are different
> 
> ...


So it is the paint after all...I was right. Who'd o' thunk it :laughing:


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## eddiecalder (Jul 15, 2008)

The plastic liner on the inside and the paint on the outside.


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## OldSchool (Jan 30, 2010)

eddiecalder said:


> Ok here is the best I can do
> 
> People are using the terms Electrolysis and Galvanic corrosion interchangeably. They are different
> 
> ...


Actually it has more to do with the PH of the liquid and the metal

Different metals give off its electrons at different areas ph scale

At the specific ph for a certain metal would be considered an electrolyte sufficient to cause electrons to break free and combine with another atom

As for causing a separation between dissimilar metal is aiding the gap between the metals... Larger the gap ... Harder to trade electrons...

But the water itself has certain atoms that also cause the same reaction with in the water...

No matter what the reaction will take place with or with dielectric union

This is because neutral water is running through the pipes...

This is why it's different on a closed system .... The reaction has occurred once when the new water was introduced... No further reaction unless new water was added ... Therefore the electrolyte or ph would be neutral for the metals and no further affect


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## eddiecalder (Jul 15, 2008)

OldSchool said:


> Actually it has more to do with the PH of the liquid and the metal
> 
> Different metals give off its electrons at different areas ph scale
> 
> ...


The Rate if corrosion is determined by the electrolyte and the difference in nobility between the two dissimilar metals. 

We are saying the same thing........


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## rjbphd (Feb 5, 2010)

Just got home from working at small school... brass zone valve body,blk fittings and nipples connecting to male copper fittings going underground... no corrison at all... no die electric crap ethier


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## OldSchool (Jan 30, 2010)

eddiecalder said:


> The Rate if corrosion is determined by the electrolyte and the difference in nobility between the two dissimilar metals.
> 
> We are saying the same thing........


More or less 

Just that you don't really need dissimilar metals for it to take place...

It can happen with one metal if the ph is at the right level


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## OldSchool (Jan 30, 2010)

rjbphd said:


> Just got home from working at small school... brass zone valve body,blk fittings and nipples connecting to male copper fittings going underground... no corrison at all... no die electric crap ethier


Check the ph ... This is why the metals are not trading electrons...
Change the ph and it will fall apart in no time


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## Protech (Sep 22, 2008)

SPH said:


> For corrosion to occur there needs to be water. That plastic lined fitting prevents the dissimilar metals from meeting inside the piping.


Most dielectric fittings aren't truly dielectric. All they do is increase the resistance of the galvanic cell. The more distance, the more resistance to electron flow, and the slower the corrosion.

Ideally, you want a bunch of surface area on the less noble metal (steel) making contact with very little surface area of the more noble metal (copper).


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## UN1TED-WE-PLUMB (Oct 3, 2012)

I'm certainly no expert in this area but from what I can gather... OldSchool, you say that it can happen with only one metal.. Such as copper, this is what a neutralizer accomishes... I am on a well system here and I have a neutralizer and when I first moved in I bypassed it (just playing around basically) then all my white tubs started to turn blue from the acidic water basically carrying electrons from the coppe pipe suspended in the water.. After this started I put the neutralizer back in service and it stopped turning my tubs blue. So basically the neutrilizer balances the ph of the water which in turn stops the corrosion.

Sorry for the rant but it just sorta clicked when I read your post.


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## Protech (Sep 22, 2008)

eddiecalder said:


> The Rate if corrosion is determined by the electrolyte and the difference in nobility between the two dissimilar metals.
> 
> We are saying the same thing........


Don't forget surface area ratios and distance.


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## Protech (Sep 22, 2008)




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## UN1TED-WE-PLUMB (Oct 3, 2012)

I just recently changed an 80 electric that was only 2 years old and quit frankly I couldn't believe the amount of corrosion inside the nipple right at the female adapter. 

So if the water was ph neutral this corrosion would not occur? Even though they are dissimilar metals?

I have to google cathode now..


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## OldSchool (Jan 30, 2010)

UN1TED-WE-PLUMB said:


> I'm certainly no expert in this area but from what I can gather... OldSchool, you say that it can happen with only one metal.. Such as copper, this is what a neutralizer accomishes... I am on a well system here and I have a neutralizer and when I first moved in I bypassed it (just playing around basically) then all my white tubs started to turn blue from the acidic water basically carrying electrons from the coppe pipe suspended in the water.. After this started I put the neutralizer back in service and it stopped turning my tubs blue. So basically the neutrilizer balances the ph of the water which in turn stops the corrosion.


Exactly copper and acid ph really doesn't get along to well

For an experiment ... You guys should see what happen to aluminum at the other end of the scale .....

Try making a lye solution with water ... Then drop in some aluminum 

Instant hydrogen gas


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## eddiecalder (Jul 15, 2008)

OldSchool said:


> More or less
> 
> Just that you don't really need dissimilar metals for it to take place...
> 
> It can happen with one metal if the ph is at the right level



Yes you do (semantics)

If both metals were atomically 100% identical why would one metal be more positively charged than the other in a completely mixed solution. There would be no electrochemical imbalance and no anode and cathode. The there would be no ionic exchange. 

You are talking about corrosion and not galvanic corrosion up above. Two dissimilar metals are needed for "GALVANIC CORROSION"

It should be noted that the PH of the solution will greatly effect both the rate of galvanic corrosion and corrosion (acidic or alkaline)


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## rjbphd (Feb 5, 2010)

UN1TED-WE-PLUMB said:


> I just recently changed an 80 electric that was only 2 years old and quit frankly I couldn't believe the amount of corrosion inside the nipple right at the female adapter.
> 
> So if the water was ph neutral this corrosion would not occur? Even though they are dissimilar metals?
> 
> I have to google cathode now..


 Which why never to pipe with the female.... always use male adts into fittings..


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## OldSchool (Jan 30, 2010)

eddiecalder said:


> Yes you do.
> 
> If both metals were atomically 100% identical why would one metal be more positively charged than the other in a completely mixed solution. There would be no electrochemical imbalance and no anode and cathode. The there would be ionic exchange.
> 
> ...


What do you think the water and metals are made of ?? 

Atoms .... And they have electrons ... And that is what is being traded

The water itself is enough to create these effects and add in the impurities which will be in all water and there you have it... More than enough to cause the affect ....

Especially on domestic water... It a fresh never ending supply of new electrons to be traded...


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## eddiecalder (Jul 15, 2008)

I'm just pointing out that is is a difference between electrolysis (which we pretty much will never run into) galvanic corrosion (requires two dissimilar metals and a electrolyte no matter how you cut it) and acidic/alkaline corrosion. I know there are impurities in domestic water and I know that if you put copper in acid it will corrode.

This seems to be turning into a pissing match. SPH was correct in like the 4th post.....


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## Protech (Sep 22, 2008)

eddiecalder said:


> Yes you do (semantics)
> 
> If both metals were atomically 100% identical why would one metal be more positively charged than the other in a completely mixed solution. There would be no electrochemical imbalance and no anode and cathode. The there would be no ionic exchange.
> 
> ...


Low PH corrosion is technically corrosion at all. The metal is just being dissolved. Washed away.


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## eddiecalder (Jul 15, 2008)

Protech said:


> Low PH corrosion is technically corrosion at all. The metal is just being dissolved. Washed away.


That I'm not to sure about. You may be 100% correct.


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## UN1TED-WE-PLUMB (Oct 3, 2012)

eddiecalder said:


> I'm just pointing out that is is a difference between electrolysis (which we pretty much will never run into) galvanic corrosion (requires two dissimilar metals and a electrolyte no matter how you cut it) and acidic/alkaline corrosion. I know there are impurities in domestic water and I know that if you put copper in acid it will corrode.
> 
> *This seems to be turning into a pissing match. SPH was correct in like the 4th post...*..



Not at all.. I call it intelligent conversation. :thumbsup:


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## OldSchool (Jan 30, 2010)

SPH said:


> For corrosion to occur there needs to be water. That plastic lined fitting prevents the dissimilar metals from meeting inside the piping.


Is not true ... You need a catalyst could be many different things

I am in no pissing contest


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## Protech (Sep 22, 2008)

OldSchool said:


> Is not true ... You need a catalyst could be many different things
> 
> I am in no pissing contest


This otter has a mallet. Your point is invalid.


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## UN1TED-WE-PLUMB (Oct 3, 2012)

SPH said:


> For corrosion to occur there needs to be water. That plastic lined fitting prevents the dissimilar metals from meeting inside the piping.


I think this is the idea behind it but unless the female is screwed right up against the plastic then there will still be a small amount of galvanized nipple between the plastic and the copper. These are not dielectric fittings in my opinion.


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## eddiecalder (Jul 15, 2008)

Sometimes it's hard to decipher what is a pissing contest online. I don't want to piss fight either. I will likely have some questions in the future that you might have some insight on. I also do HVAC/R and plumbing/gas fitting like you.


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## eddiecalder (Jul 15, 2008)

I think regarding SPHs post that water can be assumed unless specified in the post. 

How do you post a avatar?


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## OldSchool (Jan 30, 2010)

eddiecalder said:


> Sometimes it's hard to decipher what is a pissing contest online. I don't want to piss fight either. I will likely have some questions in the future that you might have some insight on. I also do HVAC/R and plumbing/gas fitting like you.


Then we have a ton in common...

If it seemed like I was in a contest ... I was unaware of it... LOL


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