Re: Replacing shut off valve on the water main line

Posted by brewster on 2017/9/14 13:13:48

iGreg wrote:

Steam is moisture and moisture causes rust, there is plenty of air inside those old pipes that would certainly constitute enough oxygen (and in fact does).

Your science is rusty. Moisture doesn't cause rust, oxygen does. Moisture simply enables the oxygen to react with the iron to form iron oxide: rust. In a closed heating system like steam or even baseboard, there's no source of oxygen. Almost no fresh water with O2 is let in. This is why potable water systems that have fresh water running through them all the time NEVER use black pipe, only galv or copper. But even a baseboard boiler has everything but the actual risers and radiators black pipe.

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