Doug,
Believe you were
just lucky in choosing 10” pipe. The larger the diameter the
greater the likelihood for buckling under external load. There is no
correlation with aluminum, PVC, and UPVC…different animals.
R/J2
Respectfully,
Jay K. Jeffries
Andros Is., Bahamas
It is the mark of an educated mind to be able to
entertain a thought without accepting it.
- Aristotle
From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org]
On Behalf Of djackson99@aol.com
Sent: Monday, January 29, 2007
12:58 AM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Steel
Pipe Hull
Thanks for your help, Jay
and Jon:
Yes this is the right kind of chart, I just want it to have one more column
which would be the working PSI if the PSI force was external, aka submarine.
Look at: http://www.pveng.com/Charts/Pipe%201.03%2020ksi.pdf a 10" steel
Schedule 20, .25 wall it shows Max PSI (I think E=1 means no safety margin, right?) of 827. And when if I am using the
Hull Calculation sheet right I get 940 PSI for a 10 inch steel hull with a .25
plate thickness. But if I switch the Young's
Modulus of Elasticity to 20,000,000 to match the steel pipe it drops to 845
PSI.
So the PSI of the 10" steel pipe seems to be the same regardless of the
load being internal or external. So, if that is true, would it hold true
for larger diameter pipe? How about aluminum pipe or PVC or UPVC pipe?
Looking forward to your comments, and thanks again for your assistance.
--Doug J
-----Original Message-----
From: jon@psubs.org
To: personal_submersibles@psubs.org
Sent: Sun, 28 Jan 2007 6:16 PM
Subject: RE: [PSUBS-MAILIST]
Steel Pipe Hull
Thanks for pointing that out...it's an
important note. However, you can plug the data from the charts into the
"hull Calculator" spread sheet located at
-----Original Message-----
From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org]On Behalf Of Jay K. Jeffries
Sent: Sunday, January 28, 2007
7:00 PM
To: personal_submersibles@psubs.org
Subject: RE: [PSUBS-MAILIST] Steel Pipe Hull
Please note
these charts are for design of vessels that will experience an internal
pressure not an external pressure like a submersible. Other modes of
failure such as buckling predominate in submarine hull design so these tables
are not applicable for a PSUBS (other than the VBT or compressed air tanks).
It is the mark of an educated mind to be able to
entertain a thought without accepting it.
- Aristotle
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