What is this substance on my pipes?
July 2, 2016 7:57 PM   Subscribe

My wife and I have been removing jury-rigged insulation from our basement pipes placed there what looks like centuries ago by a previous owner. At the lowest level, on the pipe itself, we find a sporadic and uneven white substance. Can you help us identify it?

Here are some photos:


I apologize for the quality. The first photo is the one that got us worried, because we don't want this to turn out to be an asbestos coating (or residue from an asbestos coating that was half-assedly removed). But the subsequent photos, especially at the juncture points, look more like rust or limescale than something deliberately applied.

The pipes themselves appear to have been quite sweaty, which is why we think the duct-tape and insulation mess was applied in the first place.

What is it?
posted by gerryblog to Home & Garden (8 answers total)
Best answer: My first thought is corrosion, since those look like galvanized pipes. Do any of the photos here look like what you're seeing?
posted by cabingirl at 8:18 PM on July 2, 2016 [1 favorite]

Response by poster: Yeah, that was our best guess based on Googling too. Assuming it is, do we do anything? Do we just watch the affected pipes for leaks?
posted by gerryblog at 8:24 PM on July 2, 2016

Well, ultimately you're going to want to replace those pipes. They are probably restricting your water flow, and when they corrode through they can burst, and fun stuff like that. I'm just another old house owner, I think you'd need a plumber to tell you how much life is left in them.
posted by cabingirl at 8:35 PM on July 2, 2016 [2 favorites]

Response by poster: Thanks! Was planning on calling the plumber after the holiday.
posted by gerryblog at 8:38 PM on July 2, 2016

You might want to halt any more disruption to these pipes.
There's some possibility the white stuff is asbestos or asbestos-related.

Here's a picture of a pipe coated in asbestos. It's possible much of it was chipped off but some remains.

Have it tested before you touch it again to be sure, and if you can wrap it up again do that.

Asbestos in my area is more common on hot water heating pipes and not common on plumping lines. What is the purpose of these lines?

If it is asbestos, you can leave it in place and encapsulate it (are you removing a previous encapsulation?) or you can have it removed. Its not a huge problem but it's something you don't want to expose yourself to. It's expensive to deal with but it won't bankrupt you.

Stay safe, good luck.
posted by littlewater at 9:38 PM on July 2, 2016 [3 favorites]

Best answer: Asbestos exposure is not that big a deal on a very infrequent basis (surprise: there's already asbestos in the air we all breathe). It takes years and years of regular and extensive exposure for any health problems to manifest (1% risk after 10 years of regular exposure) and while the effects are devastating, they only occur oin a small percentage of the population which is predisposed to them. Even if it is asbestos (which it is almost certainly not, that's not what it looks like), use a spray bottle with water so that the asbestos fibers are not aerosolized and inhaled, bag the waste, and you'll be fine.

If you did home remodels for a living, it'd be a different story, but for one home remodeling project it's really not a big deal to just handle it yourself. There's no need for professional abatement.

I'm a construction worker and I take my health and safety very, very seriously, but when I dealt with asbestos in my own condo, even my OSHA-instructor co-workers (yes, multiple people) just said to keep things wet and not to worry about it. Like you, I thought asbestos was a super scary thing-whose-name-shall-not-be-spoken, panic immediately!!! topic before I took actual courses on the subject.
posted by halogen at 1:41 AM on July 3, 2016 [11 favorites]

I'm neither a plumber nor a chemist, but I don't think there is any reason to suspect the white stuff is asbestos. In one picture, it looks like the adjacent pipe was not covered with anything and has rusted to the familiar red-brown color. My guess is that the white power is some kind of salt that migrated from the insulation or is the result of a reaction between the insulation and the pipe.
posted by SemiSalt at 7:45 AM on July 3, 2016

Best answer: Zinc oxide is white. When a galvanized pipe begins to corrode, the zinc corrodes preferentially and turns white ("white rust"). Only after the zinc is mostly consumed does the steel start to get attacked ("red rust").
posted by Huffy Puffy at 10:57 AM on July 3, 2016 [5 favorites]

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