<div dir="ltr">Thanks guys.<div>I have to make a very embarrassing confession,,,,,</div><div>Alan jogged my feeble memory. I did buy an O2 cleaned first stage scuba regulator for just that purpose about 3 years ago and it is sitting in a box in my shop. Guess that's what happens when you stop working on your sub for too long.😎. I am hoping that won't happen again since I just retired!</div><div>Rick </div></div><div class="gmail_extra"><br><div class="gmail_quote">On Sat, Apr 9, 2016 at 10:27 AM, Al Secor via Personal_Submersibles <span dir="ltr"><<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Rick,<br>
<br>
Just use an O2 clean scuba regulator...they're good for 100% O2.<br>
<br>
Al Secor<br>
<br>
--------------------------------------------<br>
On Sat, 4/9/16, Rick Patton via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>> wrote:<br>
<br>
Subject: Re: [PSUBS-MAILIST] port ring<br>
To: "Personal Submersibles General Discussion" <<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br>
Date: Saturday, April 9, 2016, 3:10 PM<br>
<br>
Thanks<br>
SteveI am trying to keep any high pressure gas outside<br>
of the sub including O2 but cant find an O2 regulator yet<br>
that can be exposed to salt water unlike the scuba<br>
regulaters so I figured I'd have the reg attached to the<br>
sked 80 nipple just inside the sub to knock it down to LP<br>
and then to the flow meter.Rick<br>
On Fri, Apr 8, 2016 at 9:50<br>
PM, Stephen Fordyce via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br>
wrote:<br>
Hi Rick,Yep, SCH80 1/2" pipe<br>
is good to about 500bar/7500PSI per my favourite pressure<br>
rating chart:<a href="http://prochem.cloudsites.net.au/wp-content/uploads/2013/09/Prochem-Piping-Products-1-Pipe-and-Tube.pdf" rel="noreferrer" target="_blank">http://prochem.cloudsites.net.au/wp-content/uploads/2013/09/Prochem-Piping-Products-1-Pipe-and-Tube.pdf</a><br>
Hi Hank,I suspect<br>
the buckling failure mode and/or standards overriding<br>
practicalities (or just inability to achieve close enough to<br>
perfect fit) will mean that reinforcement is necessary -<br>
really interested to hear what Sean has to say on<br>
it.<br>
Cheers,Steve<br>
<br>
On Sat, Apr 9, 2016 at 2:56<br>
PM, Rick Patton via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br>
wrote:<br>
Does anyone know how much pressure a stainless<br>
steel schedule 80, 1/2" ID nipple is rated for<br>
3" long? Can it take 3,000<br>
psiRick<br>
On Fri, Apr 8, 2016 at 4:39<br>
PM, Stephen Fordyce via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br>
wrote:<br>
Hi Rick,You're correct there -<br>
the reinforcing can be in the form of thickening the small<br>
piece of pipe ("nozzle") that is welded on,<br>
rather than thickening the shell. Although it's not<br>
very practical for large holes. There are also limits on<br>
how far away the reinforcing can be before it doesn't<br>
count.<br>
Actually, for<br>
small holes, there probably isn't a requirement<br>
to reinforce. I'm not so familiar with ASME, but in<br>
the Australian Standard for pressure vessels (which is very<br>
similar to ASME), you don't have to reinforce a hole<br>
unless it's bigger than 90mm.<br>
Cheers,Steve<br>
On Sat, Apr 9, 2016 at<br>
12:21 PM, Rick Patton via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br>
wrote:<br>
while were on the subject, I need some<br>
clarification on the "replace or add what you took out<br>
of the pressure vessel skin theory" as when I wanted to<br>
add a few extra view ports, I called the captian,Ketterage,<br>
and asked about cutting extra holes in the hull and he said<br>
the same thing but then got to wondering about that<br>
statement.When you cut a hole in the hull and weld in a<br>
piece of solid round stainless steel with a 1/2" hole<br>
in it for gas/wires, you still have a 1/2" hole in the<br>
hull so that theory can only work if you take into<br>
consideration the amount of ss rod that is also on the<br>
inside and outside of the hull?If that is the<br>
case, it doesn't seem correct to use a pipe with a<br>
1/2" ID schedule 40 but you extend it inside and<br>
outside until you equal the same volume as you<br>
removed? Rick<br>
On Fri, Apr 8, 2016 at 3:34<br>
PM, Stephen Fordyce via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br>
wrote:<br>
Hi Hank and Sean,Given Hank is<br>
probably halfway through building this already and Sean<br>
might be in the middle of other things I thought I might<br>
jump in - I think I can help in general terms. The rule<br>
off thumb is if you make a hole in a pressure vessel,<br>
you're supposed to put this material back as reinforcing<br>
around the hole to keep the same pressure<br>
rating.<br>
So if you<br>
want to take advantage of the full 4" thickness<br>
(wow!!!) and associated depth rating, then you would need<br>
to reinforce the hole - and it would need to be a pretty<br>
serious reinforcement to replace that thickness of<br>
material.<br>
Alternatively, if you don't<br>
reinforce, then you lose some of your depth rating,<br>
because some of the thickness is locally credited as<br>
reinforcement. This means an amount of thickness over<br>
the rest of the shell away from the hole is basically<br>
dead weight, which may or may not be a problem depending<br>
on whether this gets lowered or is<br>
free-floating.<br>
To put<br>
it another way/thought experiment: if you could machine<br>
away all the unnecessary material after you've machined<br>
the landing area and hole, the result would look like<br>
a thinner shell with a reinforcement ring welded around<br>
the hole.<br>
Cheers,Steve<br>
PS: All that said, it seems<br>
theoretically possible that if you had a hole with a<br>
spherical hatch and the right angles, and it all mated<br>
perfectly, that with everything in compression it<br>
shouldn't matter there was a hole. Probably<br>
this doesn't account for the buckling failure mode<br>
though. This is getting a bit out of my depth (if<br>
you'll pardon the pun!).<br>
On Fri, Apr 8, 2016 at<br>
11:22 AM, hank pronk via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br>
wrote:<br>
Hi<br>
Sean,If a guy was to buy a 48inch id<br>
CNG sphere with a 4 inch shell thickness, would it be<br>
necessary to weld in a land ring and port seat. Or could a<br>
guy or gal rough cut the necessary holes then put their<br>
flange machine to work to machine seats in the shell. <br>
It seems logical to me that could be done for the hatch<br>
because the load would be supported by the same steel in the<br>
hatch. Or am I out to lunch? Hank<br>
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