[PSUBS-MAILIST] add penetrator

Mon Mar 14 23:50:29 EDT 2016

Do you have a coaming (flange on trunk) or just a pad welded in the shell as your hatch land? I'm still trying to picture this. You're saying that the flat area is larger than the hatch, to the extent that you can install a penetrator adjacent to but beyond the diameter of the hatch? I'd worry about keeping it physically protected, but otherwise would consider that okay provided it was sufficiently far away from actual load bearing area on the land - if you were to fully compress the hatch O-ring and get metal-to-metal contact, don't put a penetrator closer to the resultant bearing region than one penetrator  diameter at minimum, and preferably keep it further away. If you centered it between the edge of that load-bearing area of the hatch, and the weld on the outside of the pad, where would that put it?

Sean

On March 14, 2016 7:42:56 PM MDT, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>Hi Sean,Thank you,I intend on using a .5 inch strait fine thread
>penetrator with o-ring seal.  That is the reason for going through the
>hatch land.  The hatch land was machined flat on the top and will
>accommodate the penetrator with no machining because the penetrator has
>the recess in it for the o-ring.  Also the land is very beefy.  It may
>be better to just buy a new penetrator with more connections.  I am one
>wire short.   As always  you are big help!Hank 
>
>On Monday, March 14, 2016 7:22 PM, Sean T. Stevenson via
>Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
>
>Can you sketch or otherwise provide a picture of your idea with the
>hatch land? I can't quite visualize what you mean. There are some
>potential pitfalls, but I need to see what you're talking about.As far
>as penetrators in the hull shell, the  ASME Boiler and Pressure Vessel
>Code, Section 8, Division 2 (addressing PVHOs) refers to so-called
>"insignificant" penetrations as follows:Openings of 3½  inches or
>smaller are considered  insignificant if they are made in plate of 
>3/8  inch or less in thickness and their finishing connections  are
>welded.  The opening must not exceed 2-3/8 inches if  the  plate is
>greater than  3/8  inch thick.  Threaded, studded, or expanded
>connections may not exceed 2-3/8  inches regardless of plate
>thickness.  To qualify,  the openings must be normal orientation. Two
>adjacent openings not exceeding the sizes listed above must have a
>minimum center to center distance equal to the sum of their diameters
>in order to remain insignificant. Furthermore, two openings of
>diameters d1 and d2, in a group of three or more, must have a minimum 
>center distance equal to 2.5 (d1  +  d2) when in spherical shells or
>heads or (1 + 1.5 cos  θ)(d1  +  d2) when in cylinders or cones, θ
>being the angle from the longitudinal axis of the shell.That said, I am
>personally hesitant to use any tapered thread (I.e. NPT) fitting in a
>hull shell, and would instead recommend either a welded fitting or an
>O-ring sealed straight thread fitting. The latter, of course, requires
>a pad lest the required spot face to seat the fitting reduce the local
>shell thickness, so your options are limited.Sean
>
>
>On March 14, 2016 3:14:38 PM MDT, hank pronk via Personal_Submersibles
><personal_submersibles at psubs.org> wrote:
>Hi Sean,I would like to add one more electrical penetrator to my new
>sub and I don't want to weld in a reinforcement  for the penetrator.  I
>am thinking of drilling and threading into the edge of my hatch land .
> I am thinking it will not bother the strength of the hatch because it
>is two inches thick.  Gamma has four holes drilled and threaded in the
>bare hull with no bushing or anything.  That was certified to 1,000
>feet so I figure I can do that through the 2 inch material.  What do
>you think?Hank
>Personal_Submersib! lesmailing list
>Personal_Submersibles at psubs.org
>http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
>
>
>_______________________________________________
>Personal_Submersibles mailing list
>Personal_Submersibles at psubs.org
>http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
>
>
>
>
>------------------------------------------------------------------------
>
>_______________________________________________
>Personal_Submersibles mailing list
>Personal_Submersibles at psubs.org
>http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.whoweb.com/pipermail/personal_submersibles/attachments/20160314/4068d309/attachment.html>