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Re: [PSUBS-MAILIST] S101 / big o-ring seals



Brent,
 
 
On the subject of large O-ring sealed connections...
 
We have a diam  520 / 600 mm hatch on Kraka. It has no leaks - no leaks at all surfaced as well as submerged. Its designed for outside pressure only - but handles small inside over pressure well.
 
Its made from two parts - a seat falme cut in 20 mm steal plate, and welded to the top of the sail, and the hatch it self - with the observation dome. Its also cut in 20 mm low carbon mild steal. None of the parts have been machined prior to, or after welding. On the top part - the hatch - we have welded two rings of 6 x 6 mm solid square steal bar. The welding is only done in part - like 30 mm weld then 60 mm no weld and so on. These two rings are concentric and hold the 10 mm O - ring in position. Again none of all this has ever been machined - its just grinded a little then painted. The design will
seal even better at deep water - since the o - ring is compressed with pressure - and ultimately it will sit on the steal. I might recommend 8 x 8 steal bar for a 10 mm o-ring for deep water not to crush the o-ring.
 
In short - this simple technique can be applied to much larger flanges and is not limited by the size of machines ( e.g. lathes ) available.
 
Regards,
 
Peter
 
 
----- Original Message -----
Sent: Friday, June 29, 2007 12:46 AM
Subject: Re: [PSUBS-MAILIST] S101

Greetings Carsten,

I've been meaning to ask you and Peter about your bolted flange assembly for the machinery compartment. I know you have to machine a O-ring groove in, but did you have to machine the mating surfaces of the two flanges before and/or after welding them to the outer hull steel?  If so how did you machine flat that large of a surface, as well as the O-ring groove? Did stitch welding significantly help in preventing heat from warping the metal?  Would clamping the first flange to be welded onto a much thicker flat steel plate before welding solve the warping problem? Then clamp and or bolt the second unwelded flange to the welded flange, and then weld it?  What thickness and type of steel did you use? I've seen were on smaller flanges, builders used stainless steel to take care of the rust issues. I'm not sure if they used 304, 316 or some other type of stainless steel. I know that's a more expensive way to go, but would you guys consider it as a good option if the funds were not a big issue?

I've been looking for a practical way to do this type of machining on large surfaces. For the O-ring grove I was thinking of using a drill/mill and spin the flange through the cutting head horizontally using a jig the can hold the flange and revolve at it's center point. The Alicia sub also had this type of flange except it was bolted on the outside, and used fiberglass fairing's to cover it.

Peter it looks like you used a much thicker O-ring on your flange for Kraka then Carsten. Will a thicker O-ring give you a larger margin of err in not having the flange mating surfaces perfect?  It did in are hyperbaric chamber door.  Does a thicker O-ring have a lower depth rating?  Most of the subs I've seen used a thin O-ring for some reason. Would you guys think having a double O-ring design be a good idea to back-up the first O-ring if it failed for some reason?  What is the diameter of your O-rings, and how wide and deep is the the O-ring groove before and after painting? Is there a formula for the thickness diameter of the O-ring compared to the width and depth of the O-ring groove and pressure rating?

I'm working on a design for a 85' plus live aboard trimaran submarine with a main pressure hull diameter of 11'. I'm currently looking at using at least three large unbolt able flanges so I can build the sub inland and then truck it to the water, as well as for maintenance issues.  

Carsten I'm interesting in your type and placement of moving trim weight(s). I've looked through the pics and drawings I have of the Euronaut, and perhaps I'm blind but I don't see it.  Is it the batteries under the center walkway?

Kindest Regards,

Brent Hartwig



 


From:  MerlinSub@t-online.de
Reply-To:  personal_submersibles@psubs.org
To:  <personal_submersibles@psubs.org>
Subject:  Re: [PSUBS-MAILIST] S101
Date:  28 Jun 2007 19:36 GMT
>
>S 101 has also some influence on the Euronaut.
>Including the moving weight and the bolted machinery compartment..
>
>Regards Carsten
>
>"James Huffman" <grandadmiraldonitz@yahoo.com> schrieb:
> > Loving the S101.  Also love the Foxtrot, Typhoon, Type 212A.
> >
> >   James
> >
> >
> > Peter Madsen <peter@submarines.dk> wrote:
> >           Hi Psubbers,
> >
> >
> >   Just before design work started on our Kraka - we had a swedish visitor - he was an ex S101 crew member and had worked for yours with swedish submarines. The direct result of this visit was the construction of Kraka based on the design of S101 but "amatuerised"
> >
> >   What does Psubers think of the S101 - is it a dreamboat og too big and bulky ( if so - kraka comes out worse )
> >
> >   Personaly i am surprised to se the resembelance...and very small size of this essentially professionel submarine.
> >
> >   Regards,
> >
> >   Peter
> >
> >
> > ---------------------------------
> >   Jeg beskyttes af den gratis SPAMfighter til privatbrugere.
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