[PSUBS-MAILIST] port ring

[Rick Patton via Personal_Submersibles]

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 psi
Rick

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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>>>>
>>>
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>>
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>
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