Did you say enthusiasm? Be careful what you
wish for. ; )'
I've never seen a sub that didn't have
continuous welds on the parts of the stiffeners that contact the outer
skin. Do you know of any I can look at. Not to say that your method isn't
good, I just hadn't heard of it before. I would think it would be a rust
nightmare if done on a steel hull. Unless you back ground the part of the
ring that was going up against the outer skin like you normally would
to weld it, and then after stitch welding it, sand blasted it, epoxy
primer it, paint and then fill the groove with a product like Sika Flex
292 and then Rhino coated the whole inside of the pressure hull. I
hate having to grind and/or sandblast paint over and over and
over and over. There has to be a better way.
That's not to say that all areas of a
sub shouldn't be designed, so you can get to them for inspection and
maintenance later, as you said. That is one on my biggest things I
spend time working up designs for. I've seen so many museum and PSUBs that
were not designed this way, and it made working on them very hard if not
impossible, without doing some very serious cutting.
The RV Needlefish, for all it's great
innovations that I learn much from, had allot of areas you couldn't get to
with out destroying the bow, stern, and saddle tanks, to do so. I'm under
the impression that trying to bond fiberglass composite, over and onto a
steel pressure hull wouldn't be a good bond. This being mostly
because they expand and contract at different rates. I would like to
hear from others with more actual experience with composites on this. I'll
need to ask Karl Stanley about this as well, since Idabel has built with
composites attached directly to the paint of the steel
hull.
Will the steel hull of the R300 try to
expand and contract, at a different rate then the syntactic foam
around it, and in doing so, try to break it. Or will the syntactic foam so
insulate and absorb heat and cold changes, that they work together?
I'm thinking about casting syntatic foam
between the internal ribbing of this K-250 I'm working on, by way of
infusion molding it. I will do this after I've installed T stock steel
inbetween the support ribs horizontally, and after I've applied a Rhino
type coating to deal with the expantion and contraction of the steel. The
T stock will do basicly two things, give strength to the hull and keep the
syntactic foam from falling out, since on the K boats the support rings
only have under cut areas on one side, because they are made of rolled
angle iron as most of you guys well know.
I think I would like to heat
treat the whole completed pressure hull of my sub if I could, like Karl
Stanley did on Idabel. I'm not sure how much it cost him, but I can find
out.
http://stansub.fotki.com/the_submarine-1/the_submarine_under/heat_treatment.html
Regards,
Brent
Harwig
From: ShellyDalg@aol.com
Reply-To:
personal_submersibles@psubs.org
To:
personal_submersibles@psubs.org
Subject: Re:
[PSUBS-MAILIST] MIG Welding a Sub
Date: Thu, 26 Jul 2007
19:20:29 EDT
Well OK, here's my two cents. I've been welding for 40 plus years,
and am still learning but for my sub, tig roots and stick cover
passes.
This gives X-ray quality welds, minimum porosity, and takes a hell
of a lot longer to do.
Shielding gas on BOTH sides for the root.
For compressive welds like internal stiffeners, a stitch method
works best. You don't need continuous welds (and a continuous heat
stress zone) around the circumference of the hull when a simple ring is
being welded inside. As the pressure increases, the hull will shrink
around the ring and a little "give" here is a good thing.
Ideally, putting the completed hull in an oven would be good, but
expensive.
Minimize welds to the pressure hull by welding on
tabs, then bolting whatever in place rather than welding some
big "thing" on there. This also makes it easier to change or up-grade
when you get new ideas or need something extra for a specific
task.
Don't build anything you can't get to later. Gotta be able to grind
and paint on a regular basis.
OK......that was more like 5 cents. Keep up the enthusiasm, and
remember, this is supposed to be FUN!!!
Frank D.
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