The pipe in the picture runs from my oil tank through my basement wall and to the outside (guessing it's the vent pipe for when they fill the tank).

Should I be concerned about what it going on at the pipe/wall interface? The white stuff is very crumbly.

Any advice on how to remedy or prevent from getting worse.

Thank you.


  • To me, the white looks more like efflorescence from minerals in water seeping through that opening alongside the pipe...
    – keshlam
    Oct 7, 2015 at 15:19
  • Thanks everyone. Seem like no imminent danger for this vent pipe and I will just keep an eye on it. To prevent further decay I like the idea of trying to get some foam in there to isolate and also to seal up from the outside and make sure water isn't getting in from that side.
    – ds007
    Oct 12, 2015 at 21:16

3 Answers 3


Normally it is perfectly acceptable for copper piping to come into contact with (or even be embedded in) concrete. Pre-cast concrete block is often an exception. This is a quote from the Copper Development Assn.:

"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"

They don't call them cinder blocks for no reason, fly ash (a residue left when coal is burned) is used in their manufacture.

Check with your local code enforcement authority, but that pipe should have been protected, both against corrosion and against abrasion due to thermal expansion. You may eventually need to cut out that section and solder a new piece in. If you can disconnect it from the tank and plug the end, fill it with water to see if there are any pinholes or leaks. Solder a new piece in if you are worried (remember to disconnect and flush first, torches and oil residue/vapor do not go well together).


I always sleeve the pipes either with plumbing tape or use insulation or conduit. Sometimes as retrofit like your situation I carefully chip concrete and use spray foam to fill up the gap to isolate the pipe.


We always sleeve pipes where it goes through the wall with another short length of pipe.

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