Corrugated stainless steel gas pipe lightning strike fires

Physical-object teaching unit. Tom shows a perforated piece of CSST tubing from a house fire in Maryland. Used to illustrate (a) the converse-reading of NFPA 780's 3/16" self-protecting threshold, (b) the labor-savings vs. system-cost tradeoff for CSST vs. black iron, and (c) the rhetoric of "we met the standards" as minimum-compliance defense in product liability.

I mentioned the first day, and I passed around examples of traditional black iron pipe — which we're going to talk about a little bit later today — but also passed around some pieces of CSST tubing. I mentioned that the black iron pipe, being about a tenth of an inch thick, if it gets hit by lightning, all you do is melt a little surface, but it doesn't perforate it. The CSST, if it gets hit by lightning, creates a hole. And while cleaning out some trash the other day, I found one I can show you. [Tom produces a piece of damaged CSST tubing.] The problem is settled, but this one has a hole in it. It's easier to see on the back side, but there's one of the holes that was formed by lightning, and burned down a house in Maryland. It's just too thin. They didn't bother to read the NFPA 780 twenty years ago when they were developing the standards for that product.

Tom's largest forensic case-load topic: over a hundred houses burned. CSST, approved for residential use in 1997, is a flexible bellows that cuts plumbing time from three days to one but can be perforated by lightning ground currents, turning the wall cavity into a flamethrower. Lightning-strike location within a house is empirically unpredictable even with instrumented test homes in Germany and Florida.

[Tom holds up corrugated stainless steel tubing.] This other one down here is corrugated stainless steel tubing. This is another thing the Gas Association came up with in the 1980s. It wasn't really approved for residential use until 1997. The problem: it's got the yellow coating on a corrugated stainless steel, and if you have lightning come through — if you live in Florida, which is lightning alley, Florida has a higher density of lightning strikes than any other place in the world, surrounded by water that forms clouds that form lightning — you get hit by lightning, and you can perforate this, and now you have a flamethrower in your wall, in the interior of your house.