Copper Pipe & Mortar

[AdamCH]

Is it correct that mortar in contact with copper pipe will corrode it and must be cleaned off?

 

[Dan Robinson]

Yes

 

[Blagard]

Is it correct that mortar in contact with copper pipe will corrode it and must be cleaned off?

Contrary to the other post the answer is actually no assuming your mortar is using Ordinary Portland Cement.

The idea of protecting copper passing through cement is actually to protect it from wear due to thermal movement.

You will still find Copper waste pipes in some old properties that have been cemented in with no problems whatsoever.

In case it applies - Central heating pipes passing through walls are best sleeved to allow for the movement. offcuts of plastic overflow are handy for 15mm

For more information see:
http://www.copper.org/applications/plumbing/techcorner/problem_embedding_copper_concrete.html

 

[CBF]

tell that to the thousands of people who have had to have their unprotected copper pipes replaced in concrete/screed floors

 

[Blagard]

tell that to the thousands of people who have had to have their unprotected copper pipes replaced in concrete/screed floors

What makes you think the cement attacked those pipes. You should never fully encase copper pipes in a solid bed without some sort of protection - However it is not corrosion that is the problem!

Embedd a bare copper pipe in concrete then repeat a heating and cooling process. It will try to move as it expands and contracts differently to the concrete/screed. Somewhere it will actually be able to do that and years of rubbing aginst the concrete/screed is the problem. Once a weep starts the outside of the pipe becomes wet and the outside of the pipe will green up as any copper will on the thinned pipe. - That is normal oxidation and exposed copper does that.

So yes, lots of pipes have needed to be replaced but it is a myth that the cement has attacked the pipes, although you entirely can't blame them from thinking so when you pull out damaged and greened up pipe!

So that particular issue will continue to be a problem unless the pipes are correctly installed

 

[Dan Robinson]

Can't beat a smart a7se on a Saturday morning.

 

[Blagard]

There are cicumstances where concrete will corrode copper pipe and I can quote

"However, copper should be protected when it comes in contact with concrete mixtures that contain components high in sulfur, such as cinders and fly-ash, which can create an acid that is highly corrosive to most metals including copper."

But please note it is not cement that is the problem and the OP is talking about mortar and I replied assuming it is mortar using OPC which is most common.

 

[Norcon]

Have to agree with Blagard here.
I've just uncovered some copper pipes that were cemented over 30 years ago.
No sign of any detrimental damage.

What will do more damage is uncleaned flux and of course what Blagard said above.

 

[Dan Robinson]

Things is, who is going to carry out a chemical analysis on the concrete everytime they see it touching copper?

 

[onecog]

I'm with blagard on this.
It's thermal expansion & movement that causes a problem and not cement/concrete except for when cinders were used in the mix in days gone.
I would however always wrap any copper in denso before bedding pipes in screed etc.

 

[CBF]

There are cicumstances where concrete will corrode copper pipe and I can quote

"However, copper should be protected when it comes in contact with concrete mixtures that contain components high in sulfur, such as cinders and fly-ash, which can create an acid that is highly corrosive to most metals including copper."

yeh i googled that web site too, amazing how knowledgable some people can be with a keyboard

 

[Blagard]

Things is, who is going to carry out a chemical analysis on the concrete everytime they see it touching copper?

Dan, it tends to be from the old days when controls on such things were pretty loose. While there should not be a problem with modern materials and the awareness of old problems, it is in my opinion, always wise to protect a pipe buried in some sort of slab or wall, ideally use ducts unless it is an underfloor heating system. Passing through a brick wall such as a copper pressure relief pipe from a boiler would not really need any protection from mortar. You tell me what you do when you install such pipes? Do you drill the hole through and then wrap the pipe before you put it in? I don't think even a sleeve is necessary as movement would negligble on that.