# Forum Home Renovation Plumbing  Any problems with galvanised to brass connection?

## drewy

Hi all.  I need advice. 
Pipe (galvanised) connected to stop-tap to my toilet rusted through, so I removed it from the nearest elbow joint (also galvanised). 
I then connected a brass tube to the same galvanised elbow and connected that to a new stop-tap. 
Is there any problem with the *connection between the new brass tube and the existing galvanised elbow*?  Or should I replace the original galvanised tube with another galvanised tube?

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## m6sports

I remember learning something in metallurgy about different metals when come in contact with water and electricity with always corrode but this may not be the case with gal and brass a plumber here will be able to answer this better

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## Danny

The union with the gal and the brass will neither be as happy or long lived as the gal with the gal.

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## drewy

Thanks for replies.  A few more questions: 
1) How long would it take for the gal-brass connection to corrode through - 2 months, 2 years OR 20 years? 
2) If there will be corrosion, how do I then join the gal elbow to the new brass tube to eliminate corrosion? 
3) Will the brass tube connecting to stainless steel stop-tap also corrode?

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## Danny

Brass is made from a combination of copper and zinc. The copper content and gal creates a galvanic reaction that causes gal fittings to corrode. A lot however depends on the copper content and water quality as to how fast this happens. It won't happen overnight and the brass pipe itself won't corrode.  
Galvanised pipe on the other hand rusts internally without any help as per the bit that you have just removed. As it rusts internally, the flow becomes restricted. Again, this won't happen overnight but it will happen and galvanised pipe is nearly always replaced with either copper or PEX pipe these days. 
Considering that you have had a section of gal pipe fail, I am wondering as to the state of the rest of your galvanised piping. The biggest clue to its condition is a lack of water pressure. 
You could use PVC fittings in between. Re metal to metal, if you coat the threads with Lokseal, it should form a protective barrier between the metals.

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## drewy

> Brass is made from a combination of copper and zinc. The copper content and gal creates a galvanic reaction that causes gal fittings to corrode. A lot however depends on the copper content and water quality as to how fast this happens. It won't happen overnight and the brass pipe itself won't corrode.  
> Galvanised pipe on the other hand rusts internally without any help as per the bit that you have just removed. As it rusts internally, the flow becomes restricted. Again, this won't happen overnight but it will happen and galvanised pipe is nearly always replaced with either copper or PEX pipe these days. 
> Considering that you have had a section of gal pipe fail, I am wondering as to the state of the rest of your galvanised piping. The biggest clue to its condition is a lack of water pressure. 
> You could use PVC fittings in between. Re metal to metal, if you coat the threads with Lokseal, it should form a protective barrier between the metals.

  Thanks for advice!

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## Precision

i would not use pvc with loxeal or to prevent dissimilar metal corrosion. Bad combination. You need a dilectric fitting which is made for exactly this scenario. Most plumbing supplies have them on request.

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## Danny

To protect against galvanic corrosion, metal pipe work should ideally be  of the same material. Dielectric couplings prevent metal to metal  contact but it must be remembered that water is the conductor and a  dielectric coupling does not stop water conduction between dissimilar  metals. As such, they do not provide absolute protection, particularly  in areas of hard water, i.e., greater conductivity.  
Many plumbers use brass couplings and this has actually found regulatory  favour overseas. Of interest, in the U.S., the NC Plumbing Code states:  605.24.1 Copper or copper-alloy tubing to galvanized steel pipe. Joints between copper or copper-alloy tubing and galvanized steel pipe shall be made with a brass fitting or dielectric fitting. The copper tubing shall be soldered to the fitting in an approved manner, and the fitting shall be screwed to the threaded pipe. 
Copper pipe is 99.9% copper whereas brass has a variable content and the % of copper content in brass pipe is higher than in brass couplings. With  many brass fittings now coming from China and with copper prices very  high, the copper content of brass has decreased but the percentage of  copper content in fittings is mostly unknown.  
The O.P. has fitted a brass pipe, not copper, but I do express concern  about the condition of the (assumed) remaining galvanised pipe. I think  this is potentially the bigger problem due to the corrosion properties  inherent with galvanised pipe.

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## Precision

A dielectric fitting does stop water conduction between two metals. Thats what they are for. Thats what they do.

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## Danny

Hi Precision, 
I don't want to spend too much time on this but I think that the  properties of electrochemical reaction and the role of the electrolyte  has been confused with the explanation as to the purpose of dielectric  fittings. I also don't want to risk been seen as either decrying or  lacking an understanding of the purpose or usefullness of these  fittings. I previously posted:   

> Dielectric couplings prevent  metal to metal  contact but it must be  remembered that water is the conductor and a  dielectric coupling does  not stop water conduction between dissimilar  metals. As such, they do  not provide absolute protection, particularly  in areas of hard water,  i.e., greater conductivity.

  By posting this, my intention was to convey that while a dielectric fitting does prevent metal to metal contact between *the two nearest metals*, the water can continue to carry an electrical current *between two dissimilar unprotected metals either side of the fitting*,  particularly in areas of hard water. After I re-read my post, I can see that this was not succinctly conveyed.  :Damn:  
I also understand that your reference:   

> A dielectric fitting  does stop water conduction between two metals

   was intended to refer  to the two nearest metals that the dielectric fitting protects. However, if the post is  in fact claiming that a dielectric fitting stops the flow of a current  along the electrolyte, then the post is erroneous. This belief  is not uncommon.  
I have the results of tests conducted by the Pittsburgh Testing  Laboratory on galvanised pipe connected to copper pipe by various  couplings that show varying current readings in each instance. The  tests were commissioned by a major international company represented in  over 3 dozen countries, including Australia. The current that flowed past their own dielectric  fitting recorded the lowest reading in the independent test results and their advertising of their dielectric fittings state that their fittings *reduce* the galvanic cell. I can PM the test results to you if  you like. 
An electrically bonded water pipe will negate a dielectric fitting and  plumbers rarely check for this condition. It really comes back to it been  best to have a continuity of like material the full length of the pipe.  
A pipe is thinnest and weakest along its threaded area and should the dielectric barrier be compromised during soldering or fitting, the small exposed threaded  area will suffer rapid degradation. As such, it can be risky to chance amateur  intervention with fitting.

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## Precision

A dielectric fitting is the best solution to the posters problem. His incoming water service from the authority's main is a combination of many metals leading up to the domestic branches contained in his own home. A pvc-u fitting used instead is not a good option and even worse so with loxeal. Pvc-u is plagued with many problems when used for domestic water even though it is an approved material. It should be used with thread seal tape at best if no other option is available.

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## Danny

Precision, 
Twice now you have posted that I recommended using Loxeal with PVC  fittings. If you re-read my original post, you will see that this is not  the case. 
I understand where you are coming from when recommending the use of a  dielectric fitting but it must be remembered that you are a plumber and  the OP is not. While a plumber would (or should) know how to fit one  without compromising the integrity of the plastic barrier that separates  the two metals, the OP obviously had no such experience or knowledge about these fittings. Given that it was a brass pipe and not a copper pipe that had been connected to a galvanised pipe, many plumbers would have used a brass fitting. I would like to think that a good plumber would use a dielectric fitting in preference to a PVC or a brass fitting but many don't. Nevertheless, using a PVC fitting is acceptable and they are somewhat more integrant than a dielectric fitting that has a plastic sheath that can be damaged during fitting. 
A PVC fitting serves the same role as a dielectric fitting in that they both prevent metal to metal contact but neither stops the current flow along the electrolyte between nearby dissimilar metals despite your claim of *"A dielectric fitting does stop water conduction between two metals"*. This is why dielectric (and PVC) fittings fail when fitted to pipe work that has been electrically bonded. The probability of such a situation been in place in the area of pipe work that the OP described is miniscule but such required knowledge is why plumbers undertake years of training and why in Victoria where the OP resides it is illegal for unqualified persons to undertake such work. Some may see such regulations as Draconian but familiarity without due knowledge can often lead to property damage and/or health/safety issues when DIYers use their 'experience' learnt in one area to fix the 'same' assumed problem in another area.  
As a minimum when recommending the use of such fittings, posters and thread visitors should be given some knowledge as to their proper use and their possible limitations when used in some other situations.

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