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Re: [PSUBS-MAILIST] Design depth
Jon,
The missing link seems to be; what sort of margin do you have between your test depth or rated depth
and your crush depth. For instance, if a submarine should fail in theory at 1000ft one person might test
it to 900ft, divide that by 1.25 & say it's rated to 720ft; whereas someone else with the same design
may test it to 500ft & say it's rated for 400ft.
I'm not familiar with ABS or ASME but wouldn't there be some sort of regulation that stipulates a margin
of error, & if your boiler for instance will blow up at 1000 psi then it's only rated to 400psi despite any testing.
Maybe some of the engineers could wade in on this & advise us of a general margin of safety that is applied
steel design in engineering applications where life is at risk. Or advise some nominal % figure in relation to how
close to the theoretical crush depth the pressure test should be taken.
Regards Alan
----- Original Message -----
From: "Jon Wallace" <jonw@psubs.org>
To: <personal_submersibles@psubs.org>
Sent: Friday, December 10, 2010 8:33 PM
Subject: Re: [PSUBS-MAILIST] Design depth
Alan,
For design and fabrication we've adopted the ABS rules by default,
unless we specifically vote to recommend something else. So technically
right now our "policy" would be that your safety margin needs to meet or
exceed ABS requirements (1.25x design depth). If you want to codify
them in our own regulations, or suggest increasing the margin, go to
http://www.psubs.org/guidelines/PSUBS/ and click on the "Submit
Proposal" link. Fill out the template and send it to me, then I can
forward to the group for a vote. If you are satisfied with the ABS
requirements, there's no need to do anything.
Jon
We are voting at the moment on adopting the 100 % rule for calculating
hull reinforcement, but the strength of the hull is only important
relative to your operating
depth & it doesn't seem we have a standard on this relationship.
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