Manwich hot water tank stress corrosion cracking

Tennessee food plant making Manwich sauce. Stainless steel hot-water hold tank held below 210°F (so excluded from boiler & pressure vessel code scope). Bleach cleaning chemical migrated under insulation, producing chloride SCC that no inspector saw because no one removed insulation. Tank "looked like a dried riverbed" of cracks when it failed; people killed.

There's a company in Tennessee making Manwich. Anyone ever had a Manwich sandwich? A little tomato barbecue sauce you mix with some ground beef. My grandson loves it. They're making Manwich, and they have this stainless steel hot water tank to hold — well, it's supposed to be water, not steam — that, if the Manwich line stops, has to keep the Manwich tank above 180 degrees, because if it drops below 180 those little bugs can start growing and my grandson's going to get sick. To stop the line for an hour or two if something's gone wrong, they have this hot water tank.

Food-processing plant case. 304 stainless hot water tank under insulation, attacked by Clorox cleaning cycle in chloride-oxidizing environment. Tom corrects an earlier reference (apparently from previous lecture) — it was Manwich, not tomato paste.

Yesterday I spoke about the little pressure vessel — it was actually Manwich. It was a hot water tank that was 304 stainless steel, covered with insulation, and they got corrosion under the insulation, because they had to go in there and clean as a food plant, and they had to clean with Clorox and everything else. What's better to destroy the corrosion protection of stainless steel than Clorox in an oxygenating chloride environment? It was Manwich, not tomato paste — tomato paste with spices costs three times as much.

Food plant disinfection regimen (bleach spray over stainless steel insulated tank) produced corrosion under lagging at the 200–210 °F operating window. Used to illustrate the corrosion-under-insulation mechanism.

I had a situation with the company that makes Manwich — the supplements with the ground beef. They were making Manwich, and it turns out you have to keep the product above 200 degrees Fahrenheit or you have to scrap it, throw out all the food. So they had a jacket — basically a hundred-gallon hot water tank — and people design these things to operate at 200 degrees Fahrenheit, but it had to be operating between 200 and 210 because you had to keep the product above 200. Every day this was a food plant and they had to disinfect. So what do they use? Bleach. You spray it on. It kills bugs. It also corrodes stainless steel like gangbusters.

99-gallon hot water tank (designed under ASME-exempt threshold) holding Manwich sloppy joe product at 210°F; nightly chloride disinfectant migrated under insulation; 304 stainless stress corrosion cracking; tank exploded scalding a worker with 200°F steam.

If you put under-insulation corrosion — if you've got some piping and you have a flood and the insulation gets wet, the wet insulation creates this nice wet-dry type of environment, just like my roof out there in Arizona. Under-insulation attack is a common problem. They were making Manwich down in Knoxville, Tennessee — sloppy joes, right? When you're making the stuff continuously, everything's fine. But when you stop for some reason, you actually have to keep that product above 190 degrees Fahrenheit by the FDA standard, so you don't grow bacteria. They had this hot water tank that was supposed to be operating at 210 degrees. The set point was 210 degrees. Water boils at 212. They wanted to get as much out of this tank as they could.