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A couple of years ago, my mom was making some sort of Irish dish for St. Patrick's day in her Presto cast aluminum pressure cooker that she'd had for 30+ years. She hadn't done maintenance on it, nor especially the gasket, and for some reason, she couldn't open it once she was done cooking and had relieved the pressure. After all attempts to save the meal had been exhausted and we'd moved on, a couple days later, I got the idea to hydro the thing until it broke. My mom, resigned to the fact she'd not be able to salvage the pressure cooker, turned it over to me. I dug out my boiler hydro'ing hand pump, got the garden hose out, and set the whole thing up out on the deck at my parents' house so my parents and my wife could watch.
I removed the fitting in the top for the safety weight/valve and installed a compression fitting and a copper line to my pump. The little button that sticks up when there's pressure was going to be an issue, to I pulled it and its rubber seal out with pliers, tapped the hole for 1/4" NPT and used it as a way to get the air out while filling. After installing a plug in the newly tapped hole, I started pumping. Granted, this water was something like 50 F degrees, but the pan finally blew just shy of 150 psi. That's a nice factor of safety for 15psi...
The failure was slightly dramatic, but not dangerously so- the bottom of the pan ruptured. As it let go, it made a "boop" sound and hopped 1/2" - 1" and that was it. There was a fracture on the bottom side in something like an X and that was all. It was still in one piece, with the roast still in there.
To finish the job, I disassembled the setup tossed the failed pan off the deck (15-20ft down to the grass) so I wouldn't have to carry it through the house, and proceeded to open the pan with a sledge hammer. That was a tough pan!when it finally gave up, the aluminum lid was more brittle than the body, but it all eventually gave way to the sledge. The roast is long gone, but I think I still have the fragments of the pan awaiting to someday be melted down for some casting project I likely have yet to think up (unless I get the scrapping bug before then). The post mortem included examining the seal- it had apparently decided it wanted to bond to both the lid and pan at various and random places. While I did pull and scrape most of it off, I think there are still some remnants of the seal still remaining on the shards of the pan and lid.
Unfortunately, no pictures seem to have been taken or this event.
Adam
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