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nolanhoff t1_j1hs956 wrote

Reply to comment by ubermaker77 in Still using a 1930s pressure canner (from National Pressure Cooker Co.) that's been used by my family for 5 generations by ubermaker77

Because it’s aluminum it will fail at some point. It isn’t ferrous, so it doesn’t have an endurance strength( Infinite life). How many stress cycles it can endure, I can’t tell you. It all depends on how they designed it.

Pressure vessels are usually required to have a factor of safety of about 6, but I’m not sure if something like this would need to adhere to that. If it did have that high factor of safety, it would last quite a long time.

For a reference point, it could be designed for 10,000 or 100,000 or 1,000,000 cycles. You’d have to ask the engineers who designed it that question.

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blueballz76 t1_j1ibhc9 wrote

It's a pressure vessel, that means it cannot be designed for infinite life, all pressure vessels eventually fail.

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frickenfantastic t1_j1iphpm wrote

For similar pressure vessels in industrial service (like 50,000 gallon tanks), we'd not let a unit like this be operated without a fitness for service test every ten years or so.

Any company that does fitness for service tests for industrial equipment could probably do the same tests (ultrasonic thickness, joint/weld testing, etc) and make a determination if the vessel is safe to keep using, but I'd expect that to be cost prohibitive.

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LeonardTimber t1_j1ikdjk wrote

Small nit pick - ‘ferrous’ just means it has iron in it and does not guarantee infinite cycle life. Cast iron or pig iron, for example, have a cycle limit.

For some reason, the inclusion of Carbon with Iron is what makes a material with infinite cycle life under a certain load, so Steels are generally the only materials with infinite cycle life at low cycle loads.

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ubermaker77 OP t1_j1irxrt wrote

Well, I can't imagine that this has been through more than 1k-2k cycles, max. My mom had it in storage for the better part of ~20 years and only used it a few times. This isn't and hasn't been used with commercial/industrial frequency, people, just 5-10 times a year. All the evidence I have supports that it's completely safe if used and maintained properly.

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SadElkBoy t1_j1iymc4 wrote

I don’t know if I would use a potential blast device without knowing it’s life. Sorry, not worth it

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jollygreengrowery t1_j1j9kad wrote

I feel like using old space heaters is bad for the same reason.

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nolanhoff t1_j1jk4ht wrote

Electric space heater?

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jollygreengrowery t1_j1jn2xf wrote

Yea the electric ones. You'll see them at yard sales for $5... the cord will have been repaired at least once and it was likely made 20-35 years ago

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nolanhoff t1_j1jn9qr wrote

Eh, other than no safety measures I don’t believe anything due to fatigue could fail, much less cause a fire.

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