"cleaning" pipe exterior...


Old 11-12-02, 08:41 AM
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Question "cleaning" pipe exterior...

I figure this is probably a better forum for this question than the heating/cooling forum.

I have a 1-pipe steam heat system in the house I recently bought. The previous owner had a leak in the boiler water release valve and appears that is was dripping water down onto the surrounding pipes (which include the gas supply line/valve and one of the main steam pipes (not sure off the top of my head if it's outgoing steam or returning condensation pipe). The leaky valve was replaced just prior to buying the house, but the pipes that were being dripped on are covered in places with what appears to be corrosion. The steam pipe shows the heavyest corrosion and is (without measuring) a 2" or 2 1/2" cast iron pipe painted silver. Some of the rust looking substance rubs right off to reveal a nice smooth pipe surface (perhaps impurities in the water left behind when it evaporated), but at some points the pipe surface is very rough with some small protrusions (like mini stellactites - like in caves, if I butchered the spelling). I want to remove some of this hardened material to get an idea of the structual integrity of the pipes.

It could be that the rough areas are just hardened minerals/impurities that were in the boiler water (that happen to be rust colored) that dried in layers in the underside of the pipe or it could be that the constant moisture has caused the pipes to begin rusting. In either case I want to get down to the actual pipe suface to assess the damage or lack thereof.

What would be the safest/best way to get this stuff off of the pipe or remove it so I can get down to the cast iron (or what's left of it) pipe and see what I've got, but with mininal damage to the pipe that's left. The gas pipe doesn't seem to be in as bad a shape asside from some badly corroded wire terminals and leads at the gas valve, but I'd still like to clean it up if possible.

Is there a sand paper type product or perhaps chemical solution that might serve this purpose. I obviously don't want to be too rough on the area incase it is already weakened. I also don't have a lot of clearance with pipes a few inches above and below and limited rear access because that's roughly where the boiler is.

Buy the way whoever designed the pipe layout for the boiler should be hung up by their eye lids. Who designs a system so that if the only external fluid valve in regular use fails, it drips on the gas supply line and gas valve?

thanks for any help,

Old 11-12-02, 10:57 AM
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Typically steam pipe is run in black pipe (steel pipe) but can be run in galvanized as well (would appear to be painted silver), the galvanized is not recommended and would be less likely... Someone may have chosen to paint the pipe as a matter of preserving it... In any case, the rust can be started from the outside and in the areas where it is beginning to rust mildly from the outside, I dont believe I would do anthing more than you might do to a battery terminal... Just steel brush it a bit, and spray some type of anti corrosive on it... As to the "stalagmites", I would not do much to those except maybe spray them with some type of anti corrosive without brushing them up much... You will find in many cases that these spots have rusted nearly completely through and if you scrape these little mounds off, you may very well expose a hole that is rusted all the way through... You will likely cause more harm than good... If you have very much of that type of damage, it is likely worth your while to look at replacing the bad sections...

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