Chinese concrete

[Marc]

Yesterday's inspection of a 30 year old, wood framed, slab supported dwelling revealed spotty but severe corrosion on some copper fresh water lines that were stubbing up through the slab. No vinyl tubing protects these stub ups. Additionally, one failure of a copper line seems to have occurred already about a year ago. PEX pipe was used to replace the isolated run of copper.

Question is this: Is this not similar to the elemental sulphur that some claim is the culprit in Chinese drywall? How did this corrosive end up in concrete 30 years ago, assuming that's what the problem here is?

The tabby is just pitching for a position as assistant inspector.

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Marc

[hausdok]

Hi,

If it's a 30-year old home it might not have anything to do with the concrete. There was a bunch of copper pipe made in Japan that was sold back around the mid-70's to mid-80's that tends to corrode and develop pinholes. You might have just discovered a batch that's taken longer than most to start leaking.

ONE TEAM - ONE FIGHT!!!

Mike

[Chad Fabry]

Concrete is alkaline. It normally takes a while but moist concrete will be aggressive to copper. Just about every water service line I see is a lovely shade of verdigris at the penetration site.

[gtblum]

Hi,

If it's a 30-year old home it might not have anything to do with the concrete. There was a bunch of copper pipe made in Japan that was sold back around the mid-70's to mid-80's that tends to corrode and develop pinholes. You might have just discovered a batch that's taken longer than most to start leaking.

ONE TEAM - ONE FIGHT!!!

Mike

Got any more info on that pipe, Mike?

One of the local plumbers says there was a development built around here in the 70's with some bad type M.

I guess they had to gut and re-plumb one house.

[hausdok]

Nope,

I was doing a house for a plumber when he told me about it. Not long after that, I got a call from a realtor I knew, "Mike, I think something is wrong with my house. The wall of my living room feels warm." I went by. Sure enough, the wall was warm. I put my ear to the wall and could hear water running. I got my moisture meter and tested the drywall - it was very wet. "You've got a pipe burst here," I said. "No way," he said. I said, "Let's find out," and I cut the wall open. As soon as I removed that 6 by 6 inch piece of drywall a thin stream shot out into the living room. On the pipe below the pinhole - "Made in Japan." I've been looking carefully at copper pipe in 30-year old homes ever since.

ONE TEAM - ONE FIGHT!!!

Mike

[Les]

I have the same info as Mike O. Nothing documented. Also, a bizillion 3/4" brass water valves made in Poland, China and Mexico have defective casting and/or alloy. Again, I have nothing to document this, only review of 1000's of inspections.

Marc, I suspect there is nothing amiss in that house other than copper vs concrete.

[Rob Amaral]

That first photo with the cat looks like self-sealed leaks at those fittings... Leaks can start out microscopic and eventually seal themselves.

[Jim Katen]

. . . Marc, I suspect there is nothing amiss in that house other than copper vs concrete.

Well, that, and the fact that they own a cat.

If the corrosion is caused by the concrete, why is the corrosion occuring where the concrete isn't?

I think that Rob is onto something with his theory of a small leak.

Either that, or the cat's been peeing on the pipes.

- Jim Katen, Oregon