Boston warehouse fire protection piping corrosion

Tom's forensic call-back: he diagnosed the open-system corrosion from a sample alone, by inferring the chronic leak. Used to illustrate the principle "no free oxygen, no corrosion" inverted — a small chronic leak destroys the closed-system condition.

Before I get to the next point, let me show you an example. [Tom shows a section of scaled pipe.] A few years ago — years ago, a few years ago when I was 20 — someone brought me a pipe and they said it came from their fire protection system. It looked similar to this, except it was all rusty inside. This piece actually has limestone scaling on the inside — this is from a boiler system, and they didn't treat their water or they over-treated it, and they basically started precipitating out limestone on the inside of their pipes. If you do it long enough you can get hardening of the arteries. It doesn't flow through well.

Large warehouse's entire fire sprinkler system was fully occluded with rust. Root cause: a tolerated leak introduced makeup water (and fresh oxygen) to what should have been a closed system. All piping required replacement.

One time I got a two-inch diameter pipe, maybe one and a half inch, completely occluded with rust. This had been in a big warehouse, and they told me that all the pipes — this is a huge warehouse — everything was occluded. They were going to have to replace all the steel piping in their fire protection system. They wanted to do some tests. I called them up and said, you guys have a leak in your system? Oh yeah. They had a leak, a stream of water that they had just running into a drain. They'd had it for a couple of years and they didn't fix it. I said, well you're going to have to replace all your piping because of that stream of water — the makeup water is bringing oxygen into the system and corroding it. You were supposed to have a closed system that didn't have a lot of makeup water. You can tolerate a little makeup water — you always have a little bit of oxygen — but you don't just let a leak go. They just didn't bother to fix this thing. I said, well, too bad, you've got to replace all the pipes. An awful lot of iron oxide.