[PSUBS-MAILIST] port ring
Al Secor via Personal_Submersibles
personal_submersibles at psubs.org
Sat Apr 9 16:27:32 EDT 2016
Rick,
Just use an O2 clean scuba regulator...they're good for 100% O2.
Al Secor
--------------------------------------------
On Sat, 4/9/16, Rick Patton via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
Subject: Re: [PSUBS-MAILIST] port ring
To: "Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
Date: Saturday, April 9, 2016, 3:10 PM
Thanks
SteveI am trying to keep any high pressure gas outside
of the sub including O2 but cant find an O2 regulator yet
that can be exposed to salt water unlike the scuba
regulaters so I figured I'd have the reg attached to the
sked 80 nipple just inside the sub to knock it down to LP
and then to the flow meter.Rick
On Fri, Apr 8, 2016 at 9:50
PM, Stephen Fordyce via Personal_Submersibles <personal_submersibles at psubs.org>
wrote:
Hi Rick,Yep, SCH80 1/2" pipe
is good to about 500bar/7500PSI per my favourite pressure
rating chart:http://prochem.cloudsites.net.au/wp-content/uploads/2013/09/Prochem-Piping-Products-1-Pipe-and-Tube.pdf
Hi Hank,I suspect
the buckling failure mode and/or standards overriding
practicalities (or just inability to achieve close enough to
perfect fit) will mean that reinforcement is necessary -
really interested to hear what Sean has to say on
it.
Cheers,Steve
On Sat, Apr 9, 2016 at 2:56
PM, Rick Patton via Personal_Submersibles <personal_submersibles at psubs.org>
wrote:
Does anyone know how much pressure a stainless
steel schedule 80, 1/2" ID nipple is rated for
3" long? Can it take 3,000
psiRick
On Fri, Apr 8, 2016 at 4:39
PM, Stephen Fordyce via Personal_Submersibles <personal_submersibles at psubs.org>
wrote:
Hi Rick,You're correct there -
the reinforcing can be in the form of thickening the small
piece of pipe ("nozzle") that is welded on,
rather than thickening the shell. Although it's not
very practical for large holes. There are also limits on
how far away the reinforcing can be before it doesn't
count.
Actually, for
small holes, there probably isn't a requirement
to reinforce. I'm not so familiar with ASME, but in
the Australian Standard for pressure vessels (which is very
similar to ASME), you don't have to reinforce a hole
unless it's bigger than 90mm.
Cheers,Steve
On Sat, Apr 9, 2016 at
12:21 PM, Rick Patton via Personal_Submersibles <personal_submersibles at psubs.org>
wrote:
while were on the subject, I need some
clarification on the "replace or add what you took out
of the pressure vessel skin theory" as when I wanted to
add a few extra view ports, I called the captian,Ketterage,
and asked about cutting extra holes in the hull and he said
the same thing but then got to wondering about that
statement.When you cut a hole in the hull and weld in a
piece of solid round stainless steel with a 1/2" hole
in it for gas/wires, you still have a 1/2" hole in the
hull so that theory can only work if you take into
consideration the amount of ss rod that is also on the
inside and outside of the hull?If that is the
case, it doesn't seem correct to use a pipe with a
1/2" ID schedule 40 but you extend it inside and
outside until you equal the same volume as you
removed? Rick
On Fri, Apr 8, 2016 at 3:34
PM, Stephen Fordyce via Personal_Submersibles <personal_submersibles at psubs.org>
wrote:
Hi Hank and Sean,Given Hank is
probably halfway through building this already and Sean
might be in the middle of other things I thought I might
jump in - I think I can help in general terms. The rule
off thumb is if you make a hole in a pressure vessel,
you're supposed to put this material back as reinforcing
around the hole to keep the same pressure
rating.
So if you
want to take advantage of the full 4" thickness
(wow!!!) and associated depth rating, then you would need
to reinforce the hole - and it would need to be a pretty
serious reinforcement to replace that thickness of
material.
Alternatively, if you don't
reinforce, then you lose some of your depth rating,
because some of the thickness is locally credited as
reinforcement. This means an amount of thickness over
the rest of the shell away from the hole is basically
dead weight, which may or may not be a problem depending
on whether this gets lowered or is
free-floating.
To put
it another way/thought experiment: if you could machine
away all the unnecessary material after you've machined
the landing area and hole, the result would look like
a thinner shell with a reinforcement ring welded around
the hole.
Cheers,Steve
PS: All that said, it seems
theoretically possible that if you had a hole with a
spherical hatch and the right angles, and it all mated
perfectly, that with everything in compression it
shouldn't matter there was a hole. Probably
this doesn't account for the buckling failure mode
though. This is getting a bit out of my depth (if
you'll pardon the pun!).
On Fri, Apr 8, 2016 at
11:22 AM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org>
wrote:
Hi
Sean,If a guy was to buy a 48inch id
CNG sphere with a 4 inch shell thickness, would it be
necessary to weld in a land ring and port seat. Or could a
guy or gal rough cut the necessary holes then put their
flange machine to work to machine seats in the shell.
It seems logical to me that could be done for the hatch
because the load would be supported by the same steel in the
hatch. Or am I out to lunch? Hank
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